Method and apparatus for locating RFID tags
阅读说明：本技术 用于定位rfid标签的方法和设备 (Method and apparatus for locating RFID tags ) 是由 S·休伊特 A·布莱尔 K·塞夫 M·墨菲 M·威依迈 T·艾德林 于 2018-03-28 设计创作，主要内容包括：射频识别(RFID)系统包括天线阵列,以区分视线(LOS)路径与非视线(NLOS)路径。天线阵列中相邻天线之间的距离小于系统的射频(RF)信号的波长的一半。天线阵列中的每个天线也被数字控制以改变天线之间的相对相位差,从而允许数字操控天线阵列通过0与π之间的到达角(AOA)。数字操控生成根据AOA的信号幅度的图形。基于图形中局部极值(例如,最大值或最小值)的形状(例如,深度、梯度等)区分LOS路径与NLOS路径。(Radio Frequency Identification (RFID) systems include antenna arrays to distinguish line-of-sight (LOS) paths from non-line-of-sight (NLOS) paths. The distance between adjacent antennas in the antenna array is less than half the wavelength of the Radio Frequency (RF) signal of the system. Each antenna in the antenna array is also digitally controlled to vary the relative phase difference between the antennas, allowing the antenna array to be digitally steered through an angle of arrival (AOA) between 0 and pi. Digital manipulation generates a pattern of signal amplitudes according to AOA. The LOS path is distinguished from the NLOS path based on the shape (e.g., depth, gradient, etc.) of local extrema (e.g., maxima or minima) in the graph.)
1. A method of locating a Radio Frequency Identification (RFID) tag, the method comprising:
receiving a plurality of first RFID signals from a first RFID tag at a first unknown location;
designating the first RFID tag as a first virtual reference tag based on the plurality of first RFID signals;
receiving at least one second RFID signal from a second RFID tag at a second unknown location; and
determining a location of the first RFID tag relative to the first virtual reference tag based on the at least one second RFID signal.
2. The method of claim 1, wherein receiving the plurality of first RFID signals comprises receiving at least one first RFID signal from each of a plurality of angles of arrival.
3. The method of claim 2, wherein:
receiving the at least one second RFID signal includes receiving the at least one second RFID signal from a first angle of arrival of the plurality of angles of arrival, an
Determining the location of the first RFID tag includes comparing the signature of the first RFID tag from the first angle of arrival to the signature of the first virtual reference tag at the first angle of arrival.
4. The method of claim 1, wherein designating the first RFID tag as a first virtual reference RFID tag comprises determining that the first RFID tag is stationary.
5. The method of claim 1, wherein determining the location of the first RFID tag comprises:
determining a multipath profile for the RFID tag, the multipath profile representing RF power received by a plurality of antennas along at least one NLOS path and a LOS path from the RFID tag to at least one RFID tag reader;
determining a multipath profile for the first virtual reference tag, the multipath profile representing the RF power received by the plurality of antennas along a LOS path and at least one NLOS path from the first virtual reference tag to the at least one RFID tag reader; and
comparing the multipath signature of the first RFID tag to the multipath signature of the first virtual reference RFID tag.
6. The method of claim 5, further comprising:
receiving a plurality of third RFID signals from a third RFID tag at a third unknown location;
designating the third RFID tag as a second virtual reference tag based on the plurality of third RFID signals; and
determining a multipath profile for the second virtual reference tag, the multipath profile representing the RF power received by the plurality of antennas along a LOS path and at least one NLOS path from the second virtual reference tag to the at least one RFID tag reader; and
determining a position of the first RFID tag relative to the second virtual reference tag according to a multi-path profile of the second virtual reference tag based on the at least one second RFID signal.
7. The method of claim 6, further comprising:
determining a first error between the multipath signature of the first RFID tag and the multipath signature of the first virtual reference RFID tag;
determining a second error between the multipath signature of the first RFID tag and the multipath signature of the second virtual reference RFID tag, the second error being greater than the first error;
based on the second error being greater than the first error, determining that the RFID tag is closer to the first virtual reference tag than the second virtual reference tag.
8. The method of claim 6, further comprising:
detecting a change in the RFID signal from the first virtual reference tag;
detecting a change in the RFID signal from the second virtual reference tag;
performing a comparison of changes in the RFID signal from the first virtual reference tag with changes in the RFID signal from the second virtual reference tag; and
determining, based on the comparison, that the first virtual reference label and the second virtual reference label are stationary.
9. The method of claim 1, further comprising:
determining a location of the first virtual reference tag relative to a reference tag at a known location based on the plurality of first RFID signals; and
determining a location of the second RFID tag relative to the reference tag based on the location of the first virtual reference tag relative to the reference tag and the location of the second RFID tag relative to the first virtual reference tag.
10. A system for locating a Radio Frequency Identification (RFID) tag, the system comprising:
a plurality of RFID tag readers to receive a plurality of first RFID signals from a first RFID tag at a first unknown location and at least one second RFID signal from a second RFID tag at a second unknown location; and
a processor operatively coupled to the plurality of RFID tag readers to designate the first RFID tag as a first virtual reference tag based on the plurality of first RFID signals and to determine a location of the first RFID tag relative to the first virtual reference tag based on the at least one second RFID signal.
11. The system of claim 10, wherein the plurality of RFID tag readers are configured to receive at least one of the plurality of first RFID signals from each of a plurality of angles of arrival.
12. The system of claim 11, wherein:
the plurality of RFID tag readers are configured to receive the at least one second RFID signal from a first angle-of-arrival of the plurality of angles-of-arrival, an
The processor is configured to determine the location of the first RFID tag by comparing the signature of the first RFID tag from the first angle of arrival with the signature of the first virtual reference tag at the first angle of arrival.
13. The system of claim 10, wherein the processor is configured to designate the first RFID tag as a first virtual reference RFID tag in response to determining that the first RFID tag is stationary.
14. The system of claim 10, wherein the processor is configured to:
determining a multipath profile for the RFID tag, the multipath profile representing RF power received by a plurality of antennas along at least one NLOS path and a LOS path from the RFID tag to at least one RFID tag reader;
determining a multipath profile for the first virtual reference tag, the multipath profile representing the RF power received by the plurality of antennas along a LOS path and at least one NLOS path from the first virtual reference tag to the at least one RFID tag reader; and
comparing the multipath signature of the first RFID tag to the multipath signature of the first virtual reference RFID tag.
15. The system of claim 14, wherein:
the plurality of RFID readers are configured to receive a plurality of third RFID signals from a third RFID tag at a third unknown location, an
The processor is configured to:
designating the third RFID tag as a second virtual reference tag based on the plurality of third RFID signals,
determining a multipath profile for the second virtual reference tag, the multipath profile representing the RF power received by the plurality of antennas along a LOS path and at least one NLOS path from the second virtual reference tag to the at least one RFID tag reader; and
determining a position of the first RFID tag relative to the second virtual reference tag according to a multi-path profile of the second virtual reference tag based on the at least one second RFID signal.
16. The system of claim 15, wherein the processor is configured to:
determining a first error between the multipath signature of the first RFID tag and the multipath signature of the first virtual reference RFID tag;
determining a second error between the multipath signature of the first RFID tag and the multipath signature of a second virtual reference RFID tag, the second error being greater than the first error; and
based on the second error being greater than the first error, determining that the RFID tag is closer to the first virtual reference tag than the second virtual reference tag.
17. The system of claim 15, wherein the processor is configured to:
detecting a change in the RFID signal from the first virtual reference tag;
detecting a change in the RFID signal from the second virtual reference tag;
performing a comparison of changes in the RFID signal from the first virtual reference tag with changes in the RFID signal from the second virtual reference tag; and
determining, based on the comparison, that the first virtual reference label and the second virtual reference label are stationary.
18. The system of claim 10, wherein the processor is configured to determine a position of the first virtual reference tag relative to a reference tag at a known position based on the plurality of first RFID signals, and determine a position of the second RFID tag relative to the reference tag based on the position of the first virtual reference tag relative to the reference tag and the position of the second RFID tag relative to the first virtual reference tag.
19. A method of locating a Radio Frequency Identification (RFID) tag, the method comprising:
receiving a first line-of-sight (LOS) signal from the RFID tag with a first antenna;
estimating a first angle of arrival, a first phase difference, and a first frequency difference of the first LOS signal;
determining a change in the first phase difference relative to the first frequency difference;
receiving a second line-of-sight (LOS) signal from the RFID tag with a second antenna;
estimating a second angle of arrival, a second phase difference, and a second frequency difference of the second LOS signal; and
determining a change in the second phase difference relative to the second frequency difference; and
estimating a location of the RFID tag based on the first angle of arrival, the change in the first phase difference relative to the first frequency difference, the second angle of arrival, and the change in the second phase difference relative to the second frequency difference.
20. A method of locating a Radio Frequency Identification (RFID) tag, the method comprising:
receiving at least one RFID signal from at least one reference RFID tag with a plurality of antennas;
determining, with a processor operatively coupled to the plurality of antennas, an estimated location of the at least one reference RFID tag based on the at least one RFID signal;
performing a comparison of the estimated location of the at least one reference RFID tag with an actual location of the at least one reference RFID tag;
calibrating the processor based on a comparison of the estimated location of the at least one reference RFID tag and the actual location of the at least one reference RFID tag;
receiving at least one RFID signal from an RFID tag at an unknown location with a plurality of antennas; and
determining, with the processor, an estimated location of the RFID tag based on the at least one RFID signal.
21. The method of claim 20, wherein receiving the at least one RFID signal from at least one reference RFID tag comprises detecting, by the plurality of antennas, Radio Frequency (RF) power propagating along a line-of-sight (LOS) path and at least one non-line-of-sight (NLOS) path from the at least one reference RFID tag to the plurality of antennas.
22. The method of claim 21, wherein determining the estimated location of the at least one reference RFID tag comprises determining a reference multipath profile, the reference multipath profile being indicative of the RF power.
23. The method of claim 22, wherein determining the estimated location of the RFID tag comprises:
determining a multipath profile for the RFID tag, the multipath profile representing RF power received by the plurality of antennas along a LOS path and at least one NLOS path from the RFID tag to the plurality of antennas; and
comparing the multipath profile of the RFID tag to the reference multipath profile.
24. The method of claim 23, wherein:
the at least one reference RFID tag comprises a plurality of reference RFID tags,
determining the reference multipath profile includes determining a multipath profile for each of the plurality of RFID tags, an
Comparing the multi-path profile of the RFID tag to the reference multi-path profile includes weighting the multi-path profiles of the plurality of RFID tags.
25. The method of claim 21, wherein the at least one reference RFID tag comprises a plurality of reference RFID tags, and wherein determining the estimated location of the at least one reference RFID tag comprises, for each of the plurality of reference RFID tags:
determining a multipath profile for the plurality of antennas at each of a plurality of angles-of-arrival associated with the reference RFID tag, the multipath profile representing Radio Frequency (RF) power received along a line-of-sight (LOS) path and at least one non-line-of-sight (NLOS) path from the reference RFID tag to the plurality of antennas; and
calculating an estimated position of the reference RFID tag based on the multi-path distribution at the plurality of angles of arrival.
26. The method of claim 20, further comprising:
displaying, by a mobile device, the estimated location of the RFID tag to a user.
27. The method of claim 26, wherein the estimated location is located in at least one of a store, a warehouse, or a warehouse, and further comprising:
determining a path from the user to the RFID tag based on the estimated location; and
displaying, by the mobile device, a path from the user to the RFID tag to a user.
28. The method of claim 27, further comprising:
determining a path of the user from the RFID tag to a target location of the RFID tag based on the estimated location; and
displaying, by the mobile device, a path from the RFID tag to a target location of the RFID tag to the user.
29. The method of claim 28, wherein the RFID tag is a first RFID tag, and further comprising:
determining a path of the user from the first RFID tag to an estimated location of a second RFID tag en route to the target location; and
displaying, by the mobile device, a path from the first RFID tag to an estimated location of the second RFID tag en route to the target location to a user.
30. The method of claim 26, further comprising:
displaying, by the mobile device, information to a user about an item associated with the RFID tag.
31. A method of locating a Radio Frequency Identification (RFID) tag, the method comprising:
receiving reference RFID signals from respective reference RFID tags with a plurality of antennas, the reference RFID tags being at respective known locations;
receiving at least one RFID signal from an RFID tag at an unknown location with a plurality of antennas; and
determining, with a processor, a location of the RFID tag based on the at least one RFID signal and the reference RFID signal.
32. The method of claim 31, wherein:
receiving the reference RFID signal comprises receiving a reference RFID signal from each of a plurality of angles of arrival for at least one reference RFID tag; and
determining the location of the RFID tag based on the at least one RFID signal and the reference RFID signal includes determining an angle of arrival of the at least one RFID signal based on an angle of arrival of the reference RFID signal.
33. A method of locating a Radio Frequency Identification (RFID) tag, the method comprising:
receiving a reference RFID signal from at least one reference RFID tag with an antenna array;
determining a reception pattern of the antenna array based on the reference RFID signal;
receiving an RFID signal with the antenna array from an RFID tag at an unknown location; and
determining a location of the RFID tag based on the RFID signal and a reception pattern of the antenna array.
34. The method of claim 33, wherein determining the location of the RFID tag comprises:
deconvolving or otherwise correcting the RFID signal and the reception pattern of the antenna array to produce a true RFID signal, the true RFID signal including a plurality of peaks;
identifying a first peak of the plurality of peaks corresponding to a line-of-sight (LOS) path between the RFID tag and the antenna array; and
estimating a location of the RFID tag based on at least one of a length or an angle of arrival associated with the LOS path.
35. The method of claim 34, wherein identifying the first peak of the plurality of peaks corresponding to the LOS path comprises distinguishing the first peak from peaks corresponding to a non-line-of-sight (NLOS) path between the RFID tag and the antenna array.
36. The method of claim 34, wherein identifying the first peak of the plurality of peaks corresponding to the LOS path comprises distinguishing the first peak from peaks corresponding to a non-line-of-sight (NLOS) path between the RFID tag and the antenna array.
37. A method of monitoring at least one Radio Frequency Identification (RFID) tag, the method comprising:
receiving a plurality of RFID signals from the at least one RFID tag over a period of time with at least one antenna;
estimating a plurality of possible trajectories of the at least one RFID tag over the time period based on the plurality of RFID signals; and
a first track of the plurality of possible tracks corresponding to a line-of-sight (LOS) path between the at least one antenna and the at least one RFID tag is identified.
38. The method of claim 37, wherein receiving the plurality of RFID signals from the at least one RFID tag occurs at a rate of at least about 0.1 Hz.
39. The method of claim 37, further comprising:
identifying a second track of the plurality of possible tracks corresponding to a non line of sight (NLOS) path between the at least one antenna and the at least one RFID tag.
40. The method of claim 39, wherein identifying the second trajectory comprises identifying a discontinuity in the second trajectory.
41. The method of claim 37, wherein the RFID tag is on an item for sale in a store, and further comprising:
determining, based on the first trajectory, that a customer is carrying the item for sale to an exit of the store; and
triggering a sale of the item at a point in time based on the first trajectory.
42. The method of claim 41, further comprising:
triggering a restock of the item for sale in response to a sale of the item.
43. The method of claim 37, further comprising:
acquiring image data of an area containing a track of the RFID tag with a camera;
identifying a person moving through an area containing a trajectory of the RFID tag; and
correlating the motion of the person moving through the area with the trajectory of the RFID tag.
44. The method of claim 37, further comprising:
determining that the at least one RFID tag includes a fixed RFID tag based on the first trajectory;
designating the fixed RFID tag as a virtual reference tag; and
calibrating the at least one RFID tag using the virtual reference tag.
45. The method of claim 37, further comprising:
displaying the first trajectory of the at least one RFID tag in real-time on a graphical user interface of the mobile device.
46. The method of claim 37, further comprising:
alerting, via the mobile device, the user that the at least one RFID tag arrived at the desired location based on the first trajectory of the at least one RFID tag.
47. A method of locating a Radio Frequency Identification (RFID) tag, the method comprising:
receiving signals from the RFID tag with a plurality of antennas;
generating a first digital representation of a response as detected by a first antenna of the plurality of antennas;
generating a second digital representation of the response as detected by a second antenna of the plurality of antennas;
generating a plurality of sums of the first digital representation and the second digital representation, each of the plurality of sums being at a relative phase difference, the relative phase difference representing a different angle of arrival of the signal from the RFID tag; and
based on the plurality of sums, a location of the RFID tag is estimated.
Background
Radio Frequency Identification (RFID) technology has applications in many commercial areas, such as access control, animal tracking, security and charging systems. A typical RFID system includes a tag (also referred to as a transponder) and a reader (also referred to as an interrogator). The reader includes an antenna to transmit Radio Frequency (RF) signals and to receive RF signals reflected or transmitted by the tags. The tag may also include an antenna and an Application Specific Integrated Circuit (ASIC) or microchip. A unique electronic product code may be assigned to a tag to distinguish it from other tags.
RFID systems may use active tags or passive tags. An active tag includes a transmitter that transmits an RF signal to a reader and a power source (e.g., a battery) that powers the transmitter. In contrast, passive tags do not have a power source, but rather draw power generated by the reader through induced currents in the tag's antenna. In a passive RFID system, a reader sends a signal using a reader antenna to energize a tag antenna. Once the tag is powered on (energized), the tag sends the stored data back to the reader.
Signals transmitted or reflected by the tag may reach the reader through more than one path. For example, a signal may travel along a straight line (referred to as a line-of-sight path or LOS path) from a tag to a reader. The signal may also be reflected or scattered from obstacles (e.g., walls and other objects distributed in the environment) before reaching the reader. These paths are referred to as non line of sight (NLOS) paths. In some cases, a given signal may arrive at a receiver via multiple paths, with several copies of the signal arriving at the receiver. The reader perceives each copy of the signal originating from a different direction or angle of arrival. This phenomenon is referred to as "multipath" in the field of RFID technology.
Multipath can lead to unwanted interference and ghosting. If different copies of a signal temporally overlap, they may interfere with each other. Destructive interference causes attenuation. If different copies of a signal do not overlap each other, subsequent copies may appear as "ghosts". These ghosts may fool the receiver into determining that additional RFID tags are present.
Disclosure of Invention
Embodiments of the present technology include methods and systems for locating Radio Frequency Identification (RFID) tags. One example includes receiving a plurality of first RFID signals from a first RFID tag at a first unknown location using a system having one or more antennas or RFID tag readers. A processor coupled to the antenna designates the first RFID tag as a first virtual reference tag based on the plurality of first RFID signals. The antenna receives at least one second RFID signal from a second RFID tag at a second unknown location. And the processor determines a location of the first RFID tag relative to the first virtual reference tag based on the at least one second RFID signal.
Another example of the present technology uses a first antenna to receive a first line-of-sight (LOS) signal from an RFID tag. A processor coupled to the first antenna estimates a first angle of arrival, a first phase difference, and a first frequency difference of the first LOS signal, and determines a change in the first phase difference relative to the first frequency difference. The second antenna receives a second line-of-sight (LOS) signal from the RFID tag. The processor estimates a second angle of arrival, a second phase difference, and a second frequency difference of the second LOS signal, and determines a change in the second phase difference relative to the second frequency difference. The processor then estimates a location of the RFID tag based on the first angle of arrival, the change in the first phase difference relative to the first frequency difference, the second angle of arrival, and the change in the second phase difference relative to the second frequency difference.
Yet another example involves receiving at least one RFID signal from at least one reference RFID tag with multiple antennas. A processor operatively coupled to the antenna determines an estimated location of the reference RFID tag based on the RFID signal. The processor performs a comparison of the estimated location of the reference RFID tag with the actual location of the reference RFID tag. The processor is calibrated based on a comparison of the estimated location of the reference RFID tag and the actual location of the reference RFID tag. The antenna receives at least one RFID signal from an RFID tag at an unknown location. And the processor determines an estimated location of the RFID tag based on the RFID signal.
Another example includes receiving, with a plurality of antennas, reference RFID signals from respective reference RFID tags at respective known locations. The antenna also receives at least one RFID signal from an RFID tag at an unknown location. A processor coupled to the antenna determines a location of the RFID tag based on the RFID signal and the reference RFID signal.
Yet another example includes receiving a reference RFID signal from at least one reference RFID tag using an antenna array. The processor determines a reception pattern of the antenna array based on the reference RFID signal. An antenna array receives RFID signals from RFID tags at unknown locations, and the processor determines the location of the RFID tags based on the RFID signals and the reception pattern of the antenna array.
Another example of the present technology includes monitoring an RFID tag by receiving a plurality of RFID signals from the RFID tag over a period of time with at least one antenna. A processor coupled to the antenna estimates a plurality of possible trajectories of the RFID tag over the time period based on the plurality of RFID signals. The processor then identifies a first track of the plurality of possible tracks corresponding to a line-of-sight (LOS) path between the antenna and the RFID tag.
Another exemplary method of locating RFID tags includes receiving signals from the RFID tags with a plurality of antennas. The processor generates a first digital representation of a response detected by a first antenna of the plurality of antennas and a second digital representation of a response detected by a second antenna of the plurality of antennas. The processor generates a plurality of sums of the first digital representation and the second digital representation. Each of these sums is at a relative phase difference representing a different angle of arrival of the signal from the RFID tag. The processor uses these sums to estimate the location of the RFID tag.
Embodiments of the present invention include devices, systems, and methods for locating Radio Frequency Identification (RFID) tags. In one example, a method of locating an RFID tag includes sensing a signal from the RFID tag to the transmitter with a plurality of antennas. One or more analog-to-digital converters (ADCs) generate a first digital representation of a response detected by a first antenna of the plurality of antennas and a second digital representation of a response detected by a second antenna of the plurality of antennas. A processor coupled to the ADC generates a plurality of sums of the first digital representation and the second digital representation. Each sum of the plurality of sums is at a relative phase difference representing a different angle of arrival of the signal from the RFID tag. The method also includes estimating a location of the RFID tag based on the plurality of sums.
All combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided that these concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. Terms explicitly employed herein may also appear in any disclosure incorporated by reference, which should be accorded the meanings best accorded to the specific concepts disclosed herein.
Drawings
Skilled artisans will appreciate that the figures are primarily for illustrative purposes and are not intended to limit the scope of the inventive subject matter described herein. The figures are not necessarily to scale; in some instances, various aspects of the subject matter disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate an understanding of various features. In the drawings, like reference characters generally refer to like features (e.g., functionally similar and/or structurally similar elements).
FIG. 1A illustrates an exemplary system for locating a Radio Frequency Identification (RFID) tag in an environment having a line-of-sight (LOS) path and a non-line-of-sight (NLOS) path between the RFID tag and a receiver.
Fig. 1B illustrates an exemplary system for estimating an angle of arrival (AOA) of an incident signal.
Fig. 1C is a graph showing an example of the composite signal amplitude versus angle of arrival/phase difference before (solid trace) and after (ray) deconvolution or otherwise correction of the antenna patch pattern.
FIG. 1D shows a graph of RFID tag signal amplitude versus angle and elevation for four different RFID tags, each at a different AOA with respect to the antenna.
Fig. 2 is a block diagram of a transmitter and receiver suitable for use in the system of fig. 1A.
FIG. 3A is a flow chart illustrating a method of locating RFID tags using the same system as shown in FIG. 1A.
FIG. 3B illustrates locating RFID tags from measurements of different AOAs using virtual reference RFID tags, and multiple readers.
3C-3F are video frames showing the measured positions of the RFID tags indicated by circles and bounding boxes drawn around objects marked with RFID tags using neural networks or other computer vision techniques.
FIG. 3G is a flow chart illustrating a method for associating RFID tag measurements with image data.
Fig. 4 illustrates LOS and NLOS signal paths from a mobile RFID tag to a pair of antennas and corresponding real and "ghost" velocity vectors and trajectories derived from the LOS and NLOS signals.
Fig. 5A shows an RFID tag location system in a retail store and a warehouse.
Fig. 5B shows the RFID tag transmitter and receiver above the item of sale in the retail store of fig. 5A.
Fig. 6 shows a Graphical User Interface (GUI) of a smartphone or tablet that displays employee and product locations derived from RFID tag location data.
7A-7D illustrate the manner in which a GUI may be used to select an RFID tagged product or other item for a particular action.
FIG. 8 illustrates the manner in which a GUI may display real-time and/or historical movement of RFID tags in a store, warehouse, or other environment monitored by an RFID tag location system.
9A-9D illustrate the manner in which a GUI may be used to plan and track a pick path in, for example, a warehouse or warehouse to pull items from a pick list based on RFID tag location data.
FIG. 10 illustrates the manner in which the GUI may be used to identify and locate stray items with RFID tags.
FIG. 11 illustrates the manner in which a GUI may be used to satisfy an inventory request for RFID tagged items.
FIG. 12 illustrates the manner in which the GUI may be used to display the location of selected products marked with RFID tags on a sales area and/or in a warehouse.
Detailed Description
To date, RFID location technology has not met with expected expectations. In conjunction with computer vision techniques, the RFID location techniques of the present invention provide unprecedented speed and accuracy. In fact, it can be more than 300 times more accurate than conventional RFID location technology. For example, the systems and methods disclosed below may be used to locate an RFID tag within 50cm, 40cm, 30cm, 25cm, 20cm, 15cm, 10cm, 5cm, or 2.5cm of its actual location. With this speed and accuracy, it can be used to track RFID tagged items in real time, even with the slightest movement. This level of speed and accuracy enables items to be found and restocked almost immediately, and tracking interactions between RFID tags. For RFID tags on products in a store, this generates data on customer interactions with the product item by item, and enables autonomous checkout.
All of the techniques disclosed herein may be used with each other unless physically incompatible. For example, an RFID tag localization system may interrogate reference tags, virtual reference tags, and RFID tags from multiple angles of arrival using multiple RFID tag readers and create (multipath) signatures based on the received signals. Such a system can position tags in two or three dimensions relative to each other and/or absolute (known) positions. The resulting locations may be associated with video data for training a neural network or managing the operation of a store or warehouse. Location information may also be displayed on a smartphone, tablet, or other device for inventory and supply chain management, etc., as described in more detail below.
1 multipath and RFID Signal
To address multipath problems in known Radio Frequency Identification (RFID) technologies and accurately locate RFID tags, the systems, methods, and devices described herein use an antenna array to distinguish RF signals traveling along a line-of-sight (LOS) path from RF signals traveling along a non-line-of-sight (NLOS) path. The distance between adjacent antennas in an antenna array may be less than half the wavelength of the system's Radio Frequency (RF) signals. Each antenna in the antenna array is also digitally controlled to vary its relative phase difference with respect to the other antennas in the antenna array. Each different phase setting of the antenna array corresponds to a different angle of arrival (AOA) measured by the antenna array. As long as the array comprises three or more antennas, the antenna array can be steered digitally through an elevation angle AOA between 0 and pi (i.e. between 0 and 180 degrees) and an azimuth angle AOA between 0 and 2 pi (i.e. between 0 and 360 degrees).
Digital manipulation in turn allows a graphical or other representation of the signal amplitude to be generated from the AOA. The LOS path is distinguished from the NLOS path based on local extrema (e.g., maxima or minima) in the graph. For example, the highest (lower) steepest maximum (minimum) may be at the AOA corresponding to the LOS path. Triangulating the AOA for two or more different LOS paths yields a three-dimensional (3D) location of the RFID tag. In theory, the method can position the article to perfect accuracy under perfect environmental conditions. Under realistic indoor conditions, position accuracy better than 50cm can be achieved using this technique.
The LOS path estimated above can be used to determine the location of the RF tag via triangulation. A first antenna or antenna group is used to estimate a first LOS path to an RF tag and a second antenna or antenna group is used to estimate a second LOS path to the same RF tag. Triangulation in the two LOS paths then provides an estimate of the 3D location of the RF tag.
The above method makes use of digital steering of the antenna array and may be cost effective in practice. In addition, the method can be easily scaled up to multiple antenna arrays. These antenna arrays may be distributed in a given space (e.g., on the ceiling of a store or warehouse) to ensure that at least two antenna arrays have a LOS path to RFID tags in that space. This is particularly advantageous in indoor environments where multiple obstacles may be present. Examples of indoor applications for the RFID method include retail stores, libraries, warehouses, etc. (see more below).
Digital steering may also be used to locate other RF transceivers, including those found in smartphones, wearable devices, tablets, laptops, and other portable electronic devices with WiFi, bluetooth, or similar antennas. As with RFID tag location, described briefly above and in more detail below, the transmitter transmits a trigger signal to a device having a WiFi, bluetooth, or other RF transceiver. In response to this trigger signal, the device issues a response, which is detected by two or more receivers via LOS and/or NLOS paths. A processor coupled to the receivers manipulates the receive mode of the receivers by digitally manipulating the AOAs for different combinations of the receivers (e.g., pairwise combinations of receivers) and looking for the strongest signal from the AOAs.
2 System for distinguishing LOS and NLOS paths
Fig. 1A shows a system 100 for distinguishing a LOS path 11 from an NLOS path 13 to a device or item having an RF transceiver (e.g., RFID tag 10), a smartphone, a wearable computing device, a tablet, or a laptop. The system 100 includes an RFID reader (transmitter) 110 and two
The
For example, the system 100 may use RF signals (e.g., about 850MHz to about 960MHz) or microwave signals (e.g., 2.45GHz) in the Ultra High Frequency (UHF) region of the electromagnetic spectrum. For UHF signals, the corresponding carrier wavelength is about 31cm to about 35cm, while for microwave signals it is about 12.2 cm. In this case, the distance d between the two
Both
In one example, the reader 110 and the
In operation, the reader 110 transmits an RF signal toward the RFID tag 10. In one example, the reader 110 transmits RF signals in a given space (such as a room). In another example, the reader 110 emits RF signals with a small divergence and steers or sweeps the RF signals spatially. In either case, if the RFID tag 10 is within a given space, the RFID tag 10 may transmit a response signal as understood in the art of RFID tags.
Depending on the location of the RFID tag 10 and the
The system 100 shown in fig. 1 can distinguish between signals along the LOS path 11 and signals along the NLOS path 13 based on the respective angles of arrival (AOAs) of the signals. Discrimination may be made by determining the angle-of-arrival corresponding to extreme values (e.g., local maxima and minima) in the antenna reception pattern. For example, the
Fig. 1B shows a
where Δ is the difference in length between the two paths taken by the two
Equation (1) also represents digitally steering the antenna 122 toward different AOA θ. In this case, the phase difference Δ φ between the two
The phase difference Δ φ may vary over a range such that the corresponding AOA θ changes from 0 to π. A corresponding signal amplitude may be recorded at each AOA θ. The signal amplitude may be the coherent sum of the signals detected by the two
In system 100,
The
Additionally, knowledge of the antenna pattern can also be used to reduce the number of angles that need to be calculated for a given measurement accuracy. For example, the sensitivity of the antenna 122 may change rapidly around certain angles. At or near these angles, the step size Δ θ of the scan may be reduced to sample more AOAs and produce more accurate results. Conversely, at an angle where the sensitivity of the antenna 122 remains relatively constant, the step size Δ θ of the scan may be increased to less samples, thereby shortening the scan time and processing time.
FIG. 1C shows a graph 150 of nominal signal amplitude A versus AOA θ, i.e., A (θ), for RFID signals received by a pair of antennas 122 as shown in FIG. 1A. The
The
this deconvolution can be used to recover the true signal amplitude from AOA θ.
May be used with a known transmission pattern (e.g., a)Reality (reality)) The reference antenna of (2) measures the antenna reception pattern S (θ). Using the reference antenna as an illumination source, A can be recordedMeasured. The reception pattern S (θ) can then be calculated according to equation (2).
After deconvolution or other correction, the
3 estimating the location of RFID tags
Based on the AOA of the LOS path, the
If desired, the processor may estimate the distance between each antenna and the RFID tag based on the amplitude of each LOS signal or the Received Signal Strength Indication (RSSI) or based on the slope of the phase difference with respect to the frequency difference. With two or more range estimates, the processor may trilaterate the location of the RFID tag in addition to or instead of AOA-based triangulation. These distance estimates may be used to more accurately or more uniquely estimate the location of the RFID tag without AOA.
The slope of the phase difference with respect to the frequency difference refers to a technique commonly used in radar and radar-like systems, where the phase of the received signal is directly compared to the phase of the transmitted signal. For an item (in this case a tag) at a given distance from the reader, this phase offset should vary in a predictable manner with its carrier frequency. Thus, capturing this relative phase offset φ at multiple carrier frequencies f allows the distance from the reader to be estimated as:
where c is the speed of light.
4 training and operating RFID tag location system
The RFID tag positioning system may go through a training phase before beginning operation. In this training phase, the RFID tag location system estimates the location of a reference RFID tag or other transceiver at a known location. The system calibrates itself by comparing the estimated location of the reference RFID tag with its actual location. After training is complete, the system may locate unknown RFID tags, smart phones, and/or other devices. The system may repeat training periodically (e.g., at night, on weekends, etc.) or as needed (e.g., in response to user commands).
To clarify how an exemplary system (e.g., the system of fig. 1A) determines and estimates LOS and NLOS paths, consider a reader that emits a continuous wave (cw) RF interrogation signal at wavelength λ. In the first (training) phase, the reader interrogates a set of tags whose locations are known. These tags are referred to as reference tags. Each reference tag receives the interrogation signal and emits a signal in a response that is received in turn by each of K1 … K antennas, each of which is located along a line segment of length D, where xkkD/(K-1) is the lateral position of the kth antenna. (other antenna arrangements are also possible). Each antenna in the array detects the output of the tag and emits a complex baseband signal s representing the tag outputk。
If there are no multipaths, at angle of arrival θ, the expected spatial response for each antenna of the tag is:
(since the system is not a beamforming system, gain need not be considered). The power received in the entire antenna array in the θ direction can be calculated as:
b (θ) is also referred to as the multipath profile of the antenna array because it (i.e., B (θ)) takes into account the incident power of the signal along both the LOS path and the NLOS path. The system measures the multipath profile of the antenna array at each of several AOAs for all reference tags and for one or more readers. Once the processor has determined the AOA of the LOS path between the antenna and the reference tag, the processor can calculate the position of the reference tag using triangulation and/or trilateration as described above.
The above described techniques may be extended to 2D (or even 3D) antenna array topologies. For example, for a simple 2D array in a 2 × 2 uniform rectangular array, assuming element isotropy in the xy plane, the steering vector is given by:
wherein the position vector pxAnd pyGiven by:
and
where d represents the element spacing between rows and columns of the array.
The power received at each 3D angle (θ, φ), and thus the 3D multipath profile, is calculated by:
FIG. 1D shows 3D multipath signatures of RFID tags measured at different positions and different angles of arrival relative to a common receiver (antenna). Each graph shows RFID tag signal amplitude versus azimuth and elevation. The peaks represent the LOS path and the NLOS path between the tag and the antenna, and the highest, steepest peak in each graph represents the LOS path. These multi-path signatures can be compared to each other to determine the relative AOAs and locations of the RFID tags, as described in more detail below.
After the system has completed training (it has measured the multipath profile for all desired angles of arrival), it enters a second (operational) phase that is performed in the environment (or repeating environment). During this phase of operation, the system interrogates non-reference tags (i.e., tags with unknown locations) and calculates the multipath profile for each unknown tag/reader combination. The system compares the multipath profile of each unknown tag to the multipath profile of the reference tag to determine the location of the unknown tag.
The system may estimate the location of the unknown tag by obtaining a weighted sum of the locations of three or more reference tags, where the weights depend on the distance between corresponding multipath distributions. For example, the position of a reference tag whose multipath profile more closely matches that of an unknown tag may be weighted more heavily than the position of another reference tag. The exact weighting may be determined using a suitable distance metric, such as euclidean distance, or "metric learning," that utilizes the position of the reference tag and the estimated positions of other unknown tags. Alternatively or additionally, the system may cluster the reference label and the unknown label according to an attribute (e.g., a multipath profile) and define a representative instance of the attribute for weighting.
The system may, for example, periodically repeat the training phase to account for environmental changes, such as changes in the number and location of reference tags, and changes in the number, type, and location of obstacles causing multipath effects. The system may also be tested in a third (post-training) stage, where an unknown tag is moved through a series of known locations within the environment, for example, using a drone or robot. As in the operational phase, the system measures the position of unknown tags and compares the measured position to the coordinates of the robot or drone to determine the best distance metric for weighting the reference tag positions (metric learning).
In some cases, rather than computing a solution (e.g., AOA and LOS path) from one antenna array and then superimposing it with another solution from the other antenna array, the raw data from both arrays may be acquired to produce a single composite solution. This can produce a variety of solutions for arrays that are spaced further apart than λ/2. Aliasing solutions can be excluded by checking the plausibility of the resulting position estimate.
5 transmitter and receiver for LOS and NLOS determination
FIG. 2 illustrates an
Each reader 210 includes a corresponding digital-to-analog converter (DAC) 218. The input of the DAC218 is coupled to the
The antenna 252 receives the response signal from the RFID tag and couples it to a band pass filter 254 that filters the response signal and couples it to a circulator 256. The circulator 256 then couples all or substantially all of the response signal to a Low Noise Amplifier (LNA) 222. LNA 222 boosts the amplitude of the response signal and couples it to mixer 224, which mixes the response signal with the LO to generate a down-converted RFID signal. The low pass filter 226 removes high frequency noise and glitches from the down-converted RFID signal, which is digitized by an analog-to-digital converter (ADC)228 and fed to a
The antennas 252 shown in fig. 2 form an antenna array with a fixed or known phase difference between adjacent pairs of antennas 252. The components and connections between components in the receiver 220 and the front end 250 may be calibrated, tuned, lengthened, or tailored to provide a known and stable phase relationship between signals received by the nearest neighbor antenna 252. For example, at least one antenna of each pair of adjacent antennas may be coupled to a phase tuner (not shown) to set or adjust the phase relationship between the adjacent antennas 252. A processor (e.g.,
The system architecture shown in FIG. 2 may be used to locate any wireless system, including Bluetooth and WiFi; it will only operate at different frequencies. A system for locating RFID, Bluetooth, and/or WiFi devices may include multiple copies of the components shown in FIG. 2, one for each type of device, and operating in different frequency bands (e.g., 865-.
6 method of estimating RFID tag position
Fig. 3A illustrates a
As described above, a processor coupled to the electronic component uses the digital RFID signal to identify the AOA of the signal relative to the antenna. For example, at step 308, the processor may electronically steer the receive pattern across the antennas of one or more AOAs. In one example, the AOA may be selected in advance. For example, a uniform step size (e.g., about π/1000 to about π/10) can be used to scan an angle between 0 and π. Alternatively or additionally, AOAs may be selected based on previous measurements to reduce processing time. For example, at corners where the sensitivity of the antenna changes rapidly, the processor may use smaller steps to acquire more samples. In addition, the processor may use information about the RFID tag and the environment (including symmetry considerations) to select AOAs that are more likely to produce results, in order to reduce processing time.
The processor may select a possible AOA based on Principal Component Analysis (PCA) of previously received signals. For example, the antenna may monitor the movement of a given RFID tag. Between successive acquisitions of response signals by the antenna, the RFID tag may move only a small amount Δ L, which may be much less than the distance between the RFID tag and the antenna. In this case, the AOAs corresponding to stronger signals in these neighboring measurements may be substantially the same, and thus, the AOAs estimated in previous measurements may be used in subsequent measurements.
Each candidate AOA corresponds to a particular phase offset (also referred to as a phase setting) measured by the antenna. Thus, the processor may determine the signal strength of each AOA by: the phase difference between the digitized RIFD signals from two or more antennas is digitally adjusted with a known phase relationship (e.g., nearest neighbor antenna), and then the digitized RFID signals are coherently summed at step 310. This steers the receive mode of the antenna through each of the respective AOAs. It also generates the amplitude and phase of the signal detected by the antenna based on AOA (phase difference between antennas). This manipulation generates a pattern of signal amplitudes from the AOA (see, e.g., fig. 1C).
At
After deconvolving or otherwise correcting the antenna pattern based on signal amplitude and phase, the processor may look for a minimum (valley) rather than a maximum (peak). In this case, the processor may identify LOS and NLOS paths based on valley depth, valley width, valley slope, or some combination thereof. For example, the processor may identify the deepest, steepest valley in the representation of the signal amplitude relative to the AOA corresponding to an AOA having zero along the LOS path to the RFID tag. Other valleys may correspond to zero corners of other NLOS paths to the RFID tag.
At step 314, the processor compares the magnitude and phase at the AOA offset to determine the angle of arrival of the LOS channel most likely to represent an RFID tag. The processor may identify LOS and NLOS paths based on the height of the maximum, the width of the maximum, the slope (rate of change) of the signal amplitude with respect to the AOA, curve fitting coefficients, or a combination thereof. For example, the processor can look for the highest steepest maximum in the representation of the signal amplitude relative to the AOA. This maximum value represents the angle of the peak in the receive mode at the RFID tag that is directed along the LOS path to the antenna. Other maxima may represent the angle at the RFID tag that points to the peak along the NLOS path.
In some cases, the processor correlates the response signal with an expected response from the RFID tag. This may be done, for example, at step 308 in
At
If more than two antennas are used in
In another optional step 318, the processor may track changes in the position of the tag over time. More specifically, the processor may map the change in the smooth change in tag position to a path in 2D or 3D space. To this end, the system measures the position of the tag at many points in time, for example, at a rate of once per second or once every few seconds. It calculates the position of the tag at each point in time and then makes a vector distance determination between successive positions to determine the velocity of the tag. The processor may classify the speed of the tag by speed and direction and determine the likely trajectory of the tag based on the speed and direction, and who (likely) carries or moves the RFID tag. For example, if the tag is moving at a pace toward the exit, the system may determine that the customer is bringing the tagged item to a checkout or store exit. Alternatively, if the tag is moving quickly to or from the store, the system may determine that the employee is stocking or shelving the tagged item.
The system may also use measurements to distinguish LOS signals from NLOS signals at many points in time. If the system detects a LOS signal and one or more NLOS signals, each of which appears as a separate "ghost" tag, it can construct a trace of each signal. The trajectory of the LOS signal should change smoothly and the trajectory of the NLOS signal may change direction dramatically as the tag moves relative to the antenna and obstacles that scatter or reflect the NLOS signal. More specifically, the processor may generate the primary vector of the tag trace using time-varying measurements of the LOS signal and the NLOS signal. The vector solving for a smooth trajectory may be the LOS, and the vector solving for a rough trajectory or an impossible trajectory (e.g., due to some given or predetermined maximum speed of a person) is cast as a multi-path (NLOS) ray.
In a system with multiple pairs of antennas (i.e., three or more antennas), the processor may perform
The processor may also perform
For systems with multiple readers, the processor may resolve the angle of arrival of each principal component of the detected signal based on the location of the reader that triggered the signal. The processor may determine that those readers whose location coincidence/angle of arrival intersect share the same LOS path to the RFID tag. The processor may use this information to determine that the other rays are the result of multipath (i.e., NLOS) rather than LOS paths.
Another approach is to map the trajectory of the tag to the trajectory of the person located within the view of one or more cameras. A camera may be provided to monitor the same volume in which the RFID tag is monitored using the antenna. This method can be used in combination with the above method to provide a single trajectory as opposed to multiple trajectories with some vertical or horizontal offset. More specifically, one or more cameras may be used to detect moving pixel groups (e.g., representing a person or object tagged with an RFID tag). A processor coupled to the camera determines a trajectory of the group and assigns an RFID tag location to the group having a matching trajectory. The processor may also partition the body or perform pose estimation. For example, the processor may evaluate the difference between the trajectory of the bag swinging in the person's hand and the trajectory of the person.
One or more readers, antennas and processors may repeatedly perform
In another example, steps 302 through 314 may be performed at a predetermined time, in response to a command or a triggering event, or both. For example, steps 302 through 314 may be performed periodically (e.g., hourly, daily, overnight inventory count, etc.). These steps may be performed in response to the arrival of a new shipment, inventory or replenishment inventory activity, user command, or detection of possible theft. For example, a store manager may trigger the
In yet another example, steps 302 through 314 may be repeated more or less frequently in response to a change in the number or location of measured RFID tags. For example, if the location of the first RFID tag or the corresponding LOS path angle of arrival changes smoothly over time, the processor may determine that the first RFID tag is moving. The processor may associate movement of the first RFID tag with movement of the person based on video or image data of the person or information about the second RFID tag, the smartphone, or other RF transceiver carried by or attached to the person. If the processor correlates the movement of the first RFID tag with the movement of the person, the processor may determine that the person also carries the first RFID tag.
The processor may use the information about the movement of the first RFID tag along with knowledge of the location of the first RFID tag to trigger other actions. For example, if a first RFID tag reaches a particular area or volume or crosses a boundary around an area or volume, the processor may debit the person's account for a purchase of an item associated with the first RFID tag. The processor may also update the product inventory to reflect the movement or purchase of the product, or issue an alert if the movement of the first RFID tag is unauthorized.
7 virtual reference tag
The systems shown in fig. 1 and 2 and the process shown in fig. 3A may be used to identify "virtual reference RFID tags" or "virtual reference tags," which are RFID tags that may be used to generate accurate position estimates for other RFID tags. For scenarios where there are multiple tags between references, using virtual reference tags provides greater positional accuracy: the greater the density of the environment, the more precise the location. The virtual reference tags also enable the relative distance between items to be measured even in the absence of non-virtual reference tags. For example, even if the exact location of tags a and C is unknown, it may be very useful to know that tag B is between tags a and C.
A simple way to view a reference tag is shown in FIG. 3B, which shows a system having several RFID readers 320 a-320 c (collectively RFID readers 320) interrogating RFID tags in a store or other environment. The RFID tag reader measures LOS and NLOS signatures of the RFID tag at different angles of arrival (AOA). The graph for each reader shows the LOS signature for a subset of tags. A processor 328 wirelessly coupled to the RFID reader 320 compares the signatures to each other to generate information about the relative location of the RFID tags. This processor 328 may also be coupled to a remote server or computer network, such as the internet, to share and use information about the location of tags via a smartphone, tablet, or computer, as described in more detail below.
The processor 328 may determine the RFID tag location by fitting the signature to curves representing the reception pattern of the RFID reader, determining the peak (maximum) value of each curve, and interpolating between adjacent peaks to determine the euclidean distance between the peaks. This euclidean distance represents an error or deviation from the corresponding RFID tag and RFID reader AOA. For a pair of AOAs, if neither is known, the error represents a difference in AOAs (i.e., relative AOAs); if one AOA is known, the other can be evaluated. Multiple relative (or absolute) AOAs for a single RFID tag may be used to estimate the relative (or absolute) position of the RFID tag. For example, the location estimation accuracy is improved by collecting more data about the RFID tag with more measurements with more RFID readers on more AOAs, e.g., to more than 50cm, 40cm, 30cm, 25cm, 20cm, 15cm, 10cm, or 5 cm.
FIG. 3B illustrates the manner in which this may be used to position the
The graphs below the first RFID tag reader 320a and the second RFID tag reader 320b show the RFID tag signal amplitude versus angle of arrival for different RFID tags. These profiles represent multi-path signatures as described above, with the highest peak representing the
The first RFID tag reader 320a has two patterns: the upper graph shows the multipath signature between RFID tag reader 320a and the tag without any obstructions, and the lower graph shows the multipath signature of person 321 between RFID tag reader 320a and the left tag. Note that person 321 attenuates/alters the multipath signatures of some tags but not others and does not affect the multipath signatures received by second RFID tag reader 320b and third
Processor 328 may determine the relative position of the tags by comparing the multipath signatures of the tags to one another. In this example, the tag signature of the RFID tag closest to either reference tag 324 (e.g., RFID tags 326a, 326b) has the lowest error compared to the tag signature of the corresponding reference tag 324. The error metric used to compare multipath signatures may be Mean Square Error (MSE), Dynamic Time Warping (DTW), or any other metric that may be used to compare the similarity of signatures. Using the example of MSE, the lower the metric, the more similar the multipath signature. In comparing the multipath signature of
If repeated RFID signal measurements show that RFID tags 326a, 326b are not moving, they may be added as "virtual reference tags" even if their absolute positions are unknown (at least to the same level of accuracy as the position of reference tag 324). This process may continue for other fixed RFID tags. For example, RFID tag 326c is closest to RFID tag 326a, and therefore, its RFID signature should be most similar to that of RFID tag 326 a. If repeated measurements show that RFID tag 326c is also fixed, it may also be designated as a virtual reference tag. Continuing the process, the system may determine the order of the RFID tags (and thus the items tagged with the RFID tags). The error metric may serve as a proxy for the relative distance and may establish an estimate of the absolute position based on the relative distance and the known position of the reference tag 324.
Because the above-described method relies on the relative error of the tag signature, the method can be further improved by using signatures at multiple readers, calculating the error by the readers, and summing (or otherwise combining) the errors at different readers. This is the case where a virtual reference tag can be used to reduce position measurement errors. Once the system identifies all fixed RFID tags, designates them as virtual reference tags, and locates these tags relative to at least the nearest neighbor tags, the processor 328 may locate the desired
The 1D example laid out above can also be extended to 2D by laying out a reference label in a 2D space (e.g., a wall or floor) and comparing the errors of the label, the reference label, and the virtual reference label within the space. This example can be further extended to 3D by laying out reference labels in 3D space and comparing nearest neighbor labels.
This method can be further improved by any method of changing the RF communication channel between the tag and the reader. This may include moving the reader, changing the frequency at which the reader is operating, or even moving someone (or an object) within the space occupied by the reader and/or tag. For example, consider a person 321 walking between a virtual reference tag 326 and a first RFID reader 320a and a second RFID reader 320B, as shown in fig. 3B. The person attenuates or scatters RFID signals propagating from the virtual reference tag 326 (and the unknown RFID tags 322 and reference tags 324) toward the first RFID reader 320a and the second RFID reader 320 b. This creates a new signature set at the first and second RFID readers 320a and 320b that is imperfectly associated with the signature set prior to the channel change and, therefore, may be used to reduce errors in the estimated locations of the virtual reference tag 326 and the
The problem of using virtual reference tags tends to surround a large amount of processing power for comparing each tag signature with every other tag signature. By comparing the signature of the RFID tag first with its last signature, the amount of processing power may be reduced. If the signature does not change, no comparison is necessary. Other ways to reduce processing power include using secondary information sources (e.g., video and existing location information for the area around the RFID tag) to limit comparisons with signatures of RFID tags that are known to be close enough to each other to be significant.
To identify or designate an RFID tag as a virtual reference tag, the system measures the location of the RFID tag multiple times over a period of time as the environment around the RFID tag changes (e.g., using the methods described above). These position estimates may be distributed over an area or volume whose size depends on noise and measurement uncertainty. As the number of measurements increases, the average position estimate may converge to a smaller area or volume whose size is limited by the fundamental measurement uncertainty. Once the size of the area or volume reaches a predetermined threshold, the processor sets the appropriate tag location (e.g., the centroid of the area or volume) and uses the tag location as a reference for similar tags. The system may repeat this process until a desired number of RFID tags or group of RFID tags have been added to the virtual reference tag pool. After setting a reference tag (whose location is known), the method of calculating the location of this reference tag proves to be reliable and can be used to estimate the location of other tags.
If the location of the RFID tag changes, the system may remove the RFID tag from the pool of virtual reference tags unless similar RFID tags exhibit similar changes (e.g., due to environmental changes, such as being blocked by a person as shown in FIG. 3B). The system may identify a change in the RFID tag queue by looking at the signature of each RFID tag in the queue relative to the signature of its queue member. The system may also look for changes (or no changes) in the signatures received from other AOAs in the queue. In fig. 3B, for example, the person 321 may change the LOS signatures received by the first and second RFID readers 320a, 320B in a relevant manner, but should not affect the LOS signature received by the
Changes in the location of the RFID may be reduced in one or more of the following situations. For example, if there is not any relative change between different RFID tags, it is possible that all of the tags are blocked or moved together. In another example, the relative change is below a predetermined threshold (e.g., measurement uncertainty). In yet another example, the relative change is sufficiently brief (e.g., within one, two, or three measurement periods).
The information about the virtual reference tag may be combined with other information to increase the accuracy of the RFID tag location. For example, the RFID tag location system may use the (estimated) location of the virtual reference tags, product count data, and visual data from one or more cameras to determine the average density of the product between the virtual and/or real reference tags. In addition, visual data can be used to determine if someone is or was close enough to pick up or drop a product or RFID tag (a pose/reach estimate can also be made). If the visual data indicates that the virtual reference label or the product with the virtual reference label is moving or has moved, the system may remove the virtual reference label from the pool of virtual reference labels. Conversely, if the visual data shows that a particular RFID tag has not moved for a long period of time (e.g., hours or days), the system may designate that RFID tag as a virtual reference tag.
8 computer vision system and computer vision system training
The RFID technology described above may be used to train a computer vision system to locate and/or identify different objects captured by a camera in or coupled to the computer vision system. For example, the computer vision system may include or may be coupled to a plurality of cameras, which may be configured to monitor a wide angle area. In addition, light sources emitting light of different wavelengths and/or intensities may also be used to create different environments in order to enhance the training of computer vision systems. Training images are acquired by the camera under different circumstances.
A combination computer vision/RFID tag location system may cross-reference the scanned barcode/transaction's time stamp data, the items in the barcode/transaction, and the camera data corresponding to the location of the register or checkout station in order to pull frames containing those items. A processor running object detection on those frames may draw a bounding box around the image to generate additional marker images.
During training of a computer vision system, such as a processor executing an artificial neural network, the RFID technology described above is used to locate and identify objects in a training image. These objects are divided into discrete images that are fed into a training set of a computer vision system (e.g., an artificial neural network). Reinforcement learning can be used to filter multiple objects if the computer vision system does not distinguish objects that are too close together. Additionally, such training may train the computer vision system to identify objects, such as lights, doors, and shopping carts, which may be irrelevant during use of the computer vision system, for example, in a retail store. These objects may then be removed from the training dataset and the frames containing the images of these objects may be marked as closed frames. Because the above-described RFID technology can automatically identify objects with RFID tags in an efficient manner, a vast database of product images can be constructed without the need for human verification or verification of the contents of the database.
In some cases, the tag position may be in error with respect to the actual object. In these cases, the tag locations may be plotted frame by frame relative to the location of the person or object (e.g., a continuously moving group of pixels obtained via optical streaming or re-identification) and the distances from each set of continuous groups of pixels to each RFID tag over n frames averaged and then grouped based on which pairings yield the lowest error/average distance. The kalman filter will work properly to filter/group objects and/or objects. The first and second derivatives of the RFID tag and pixel blob motion functions may also be combined for weighting the matches. If the goal is to attribute the product to a person, the detection of the person may be performed in each frame to select only the pixels of the graphic that correspond to the person. If the goal is to capture the annotated image, then the human detection can be used to simply ignore pixels of the human figure that correspond to the bounding box generation/pixel segmentation.
Fig. 3C-3F show a series of video frames showing the movement of a shirt marked with an RFID tag. The small circle represents the estimated location of the RFID tag attached to the shirt. The box surrounds a blob of pixels (blob) to which the system associates RFID tag motion derived from RFID signals received by the RFID tag reader. As shown in fig. 3C-3F, there is a significant error between the system estimating, frame by frame, where the RFID tag is located relative to where the object actually came from, but the system is still able to relate the RFID location estimate to the pixel blob.
FIG. 3G illustrates a
Stated differently, the RFID location provides constant feedback to the artificial neural network so that it always learns what it is right in every frame and what it is wrong. This extends to autonomous checkout and human/product interaction, where
9 tracking moving RFID tags
FIG. 4 illustrates that the RFID system and process described above may be used to track RFID tags 402 moving in an environment full of obstacles, such as a store, warehouse, or warehouse. In this example, a pair of
The RFID tag reader 410 may broadcast interrogation signals over a wide range of angles, for example, via a co-directional transmitting antenna, or scan them over different angles with an antenna array as described above. A processor (not shown) wirelessly coupled to RFID tag reader 410 uses the RFID signal from RFID tag 402 to calculate
The processor may use the position measurements and/or
The processor may also use the position measurements,
In this case, processing a false RFID signal results in the appearance of the ghost RFID tag 482 shown in FIG. 4, including
The
10 RFID tag location system in a store having retail space and warehouse
Fig. 5A and 5B show different views of an RFID tag location system in a
The RFID tags 502 may be distributed throughout the
The
In operation, the
Application of 11RFID technology to high-precision object positioning
The above-described RFID tag location techniques provide fine spatial resolution and high accuracy, making them suitable for a wide range of applications, many of which are not achievable with other RFID tag location techniques. Some of these applications are described below and may be used with systems and environments similar to those shown in fig. 5A and 5B.
11.1 tracking RFID tag movement
In one example, RFID technology may be used in retail stores, particularly in all channel (also spelled omnichannel) stores. "full channel" refers to a multi-channel marketing approach intended to provide a seamless shopping experience for customers, whether or not the customer is shopping online over the phone from a desktop computer or mobile device, or shopping at a brick and mortar store. What distinguishes full channel customer experience from multi-channel customer experience is the true integration between the channels at the back-end. For example, when a store has adopted a full channel approach, a customer service representative in the store can immediately reference the customer's prior purchases and preferences as easily as a telephone customer service representative or a customer service web chat representative. Or the customer may use a computer, tablet or smartphone to view the store inventory on the company's website or application, and then purchase items through the online store or application and pick up the product at the customer's selected location.
One problem with retailers using full channel orders is detecting that items have been picked up through a full channel order. To address this problem, an RFID tag (referred to as a handbag tag) can be placed on a handbag, shopping bag, shopping cart, or any other suitable container. Each item for sale also includes or is attached to a separate RFID tag (referred to as an item tag). An antenna array monitors the position of each tote bag label and each item label. If the distance between an item tag and a tote bag tag is below a threshold (e.g., less than the size of the tote bag), the system determines that the item corresponding to the item tag is in the tote bag. To improve the reliability of the detection, the system may further monitor the movement of the bag label and the item label. If they move together a distance that exceeds a threshold (e.g., more than 1 meter), the system may determine that the item and tote bag are being carried by the customer.
The system may also monitor the mobile customer to determine if the customer has picked up the item. For example, if the item moves with the customer a distance that exceeds a threshold (e.g., exceeds 1 meter), the system may determine that the item is being carried by the customer. For example, a customer may install a user application on his/her smartphone, and the system may detect the presence of the customer's smartphone by communicating with the user application. The system may then track the movement of the smartphone (and hence the customer) using bluetooth, WiFi, LTE, 3G, 4G or any other wireless technology.
In some cases, the system may maintain a record of all smartphones that do not belong to the customer (e.g., the store's own device or the employee's personal device). Once the system detects a smartphone that is not in record, the system may determine that the customer entered the store and may track the customer's movements by tracking the smartphone.
The system may also use facial recognition, gait recognition, or other recognition techniques to track the movement of the customer. For example, a camera may be placed at the entrance of a store to identify a customer, and one or more cameras may be distributed within the store to monitor the entire store space. Each time a customer is captured and identified by the camera, the identified location may be recorded and edited along with the previous location to formulate the customer's movements. The resolution of this monitoring (e.g., the distance between two identifications of the same customer) may depend on the number of cameras in the store (e.g., a greater number of stores may increase the resolution). The system may then determine that the item was picked up by the customer if moved together by a distance greater than a threshold. Alternatively or additionally, the system may determine that the item was picked up by the customer if they appear together at more than 3 locations. The system may also determine that the item was picked up by the customer if the two locations where they appeared together were more than 1 meter apart.
The system may also update the inventory when it is determined that the item previously picked up by the customer was placed back and available for sale. If the item has not moved for a longer period of time (e.g., longer than 5 minutes), the system may determine that the item is being placed back. To improve reliability, the system may also check if there are any customers in the vicinity of the item while the item is not moving. When no customer is near the item, the system may determine that the item was placed back (e.g., because the customer who previously picked the item changed his mind and abandoned the item).
In another example, RFID technology may be used to determine whether an item is in the correct location in a store. In this case, one or more labels (referred to as shelf labels) may be placed on each shelf holding items for sale. Each shelf label identifies a particular location on the shelf for the corresponding item. Each item also has an item label. For example, a shelf label may indicate the location of a man's trousers and an item label may be attached to a strip of man's trousers. The system interrogates the locations of the shelf tags and item tags to estimate the distance between them. If the distance is below the threshold, the system may determine that the item is in the correct location. On the other hand, if the distance is greater than the threshold, the system may alert one or more store employee items that are in the wrong place and should be moved to the correct place. The system may also provide instructions to the employee as to the actual location of the item and its appropriate location.
The system may also use tags attached to any other retail fixtures (these tags are referred to as fixture tags) to determine if the item is in the correct place. In general, each fixture tag may provide information regarding the identification of the fixture (e.g., shelf, table, counter, display case, basket, grid, etc.), the location of the fixture, and the type and quantity of items in the fixture. In some cases, the type and quantity of items in the fixture may be determined based on industry standards. Alternatively, the type and number of items in the fixture may be customized for each store.
In addition, each employee may wear a tag (referred to as an employee tag). In one example, an employee may wear a bracelet containing an RFID tag. In another example, the RFID tag may be sewn into the employee's uniform. In yet another example, the RFID tag may be included in a badge worn by the employee. The system may use these tags to estimate and track the location of employees, for example, for managing inventory, as described below.
In some cases, the movement of the employee may be monitored by software without using an RFID tag attached to the employee. For example, the system may monitor the movement of an employee by tracking the employee's smartphone. In these cases, the employee may install a user application to facilitate communication between the smartphone and the system. The system may identify the employee from his/her account on the user application, for example.
In another example, the system can track employees' wearable devices, such as smart watches, activity trackers (e.g., Fitbit), or smart glasses (e.g., glasses with embedded electronics), among other devices. In this example, the system may maintain a record of the wearable devices belonging to each employee in order to identify the employee when a wearable device is detected. Systems with cameras may also track employees by the cameras recognizing as RFID tags on items held or carried by the employee.
For example, if the system determines that an item is misplaced, or should be taken from the back inventory to the correct shelf, the system may use employee tags to estimate the location of all employees. The employee closest to or moving toward the misplaced item may then be identified. The system may alert the employee to place the item in the correct place. The system may also estimate and/or measure the time required for the employee to complete the task (e.g., the time period from alarm to completion). This information can be used to evaluate employee performance and identify changes in store layout that can improve efficiency.
The system may use several criteria to determine the appropriate personnel to receive the alert. For example, the system may communicate alerts to employees based on the availability of the employee to receive and respond to the alerts. In this example, the employee may communicate their availability (or unavailability) to the system through their employee device, such as a smartphone with the user application installed. The employee may indicate that he is in other tasks that may not be interrupted.
In another example, the system may send an alert to the employee based on the proximity of the employee to the problem item. For misplaced items, proximity may be quantified by the distance between the employee and the misplaced item. For items to be placed, proximity may be quantified by the distance between the employee and the warehouse. In some cases, the proximity estimation takes into account the building or structure of the store. For example, the system may prefer to send an alert to employees on the same floor as the problem item, rather than sending an alert to employees on a different floor.
In yet another example, the system may send alerts to employees based on their ability to complete tasks. For example, if an item in the women's clothing department is misplaced, or an item is found to be lost in the women's fitting room, the system may preferably send an alert to employees in the women's clothing department rather than employees in the grocery department.
The ability to complete a task may also be determined based on the current task being handled by the employee. For example, if an employee is already handling some misplaced items, it may be more efficient for him to handle similar tasks. The system may also consult a quality assurance system to determine the competency of the employee. For example, the system may include an employee performance assessment database for each task previously processed by the employee. If the system determines that it is efficient for an employee to restock the misplaced items, the system may preferably send an alert to the employee.
In yet another example, the system may use a combination or weighted combination of the above criteria to determine the most appropriate employee to handle the problem. For example, the system may first look for available employees. Then, among these available employees, the system finds people within a certain distance of the problem item. Of these employees, the system may then determine the most appropriate employee based on the employee's ability to complete the task.
In some cases, the system may send an alert only to the most appropriate employee (determined by any suitable method). Alternatively, the system may send alerts to a set of appropriate employees, and each recipient may respond using his/her device (e.g., a smartphone). Once the recipient responds by indicating that he or she will process the task, the system may update the status of the question, for example, "in progress".
The system may also send an alert to the supervisor of the appropriate employee determined by the system. Alternatively or additionally, the system may also replicate alerts to quality assurance department personnel to alert them to the progress of monitoring the problem.
RFID technology can also be used to monitor the availability of store inventory in a real-time manner. In this case, the system may track the movement of items picked up by the customer. As described above, the system may determine that the customer has picked up an item as it moves with the tote bag. More specifically, the system may determine that an item is in a handbag using the motion/trajectory of the item RFID tag and the motion/trajectory of the handbag as determined from video data and/or data regarding the RFID tag on the handbag or in the handbag. Once the system determines that an item is picked, the system deducts the item from the available inventory. Alternatively, the system may deduct the item from inventory until the item passes a register at which it is checked out. In some cases, the system may also deduct items if the customer is wearing an item, such as a garment or a pair of shoes.
RFID technology may also facilitate verification of e-commerce orders, particularly after the shipping container is sealed. The RF signal can typically penetrate the shipping container and thus the RFID technology described above can be used to identify RFID tagged items in the shipping container. The identified items are then compared to the order corresponding to the shipment to determine if any items are missing or should not be in the shipping box. If the missing item is confirmed, the system may check an inventory or other database to see if the replacement item is in a Distribution Center (DC) or nearby store. The system may also prevent the shipping container from leaving the store and/or DC until the item is placed in the shipping container or in a separate shipment.
In some cases, RFID technology may be used in dressing rooms to track items that customers try on. The system may determine whether the items left in the dressing room have been in the dressing room for more than a threshold time (e.g., longer than 15 minutes). Alternatively, the system may track the location of items as well as the state of the dressing room. For example, where the system determines that an item is in a changing room and the changing room is not in use, the system may determine that the item remains in the changing room. In these cases, the system may alert employees to pick up the item and place it back on the shelf for sale.
The system may determine the status of the fitting room by tracking the movement of the customer or the presence of a wearable device in the fitting room. For example, the system may generate a map of fitting rooms and display the detected movements and wearable devices in each fitting room. If no devices are found in the fitting room, the system may indicate that the fitting room may not be in use. In this case, the employee may enter the fitting room to pick up the abandoned item.
The system may also determine the status of the fitting room using an RFID tag attached to a door of the fitting room (e.g., on a movable edge of the door). In this case, the fitting room door may be designed to move away from the frame when unlocked. Thus, the RFID tag is in a first position when the door is closed or locked (i.e., when the fitting room is occupied) and in a second position when the door is open or unlocked (i.e., when the dressing room is unoccupied). The system may then determine the status of the fitting room based on the location of the RFID tag on the door. Similarly, another option is to install several reference tags in or on the fitting room curtain and detect that the reference tags move closer together or farther apart as a result of someone opening and closing the curtain.
Alternatively, each fitting room may use two RFID tags: one placed on the moving edge of the door and the other on the frame of the door. Alternatively, the RFID tag may be placed on a different part of the lock on the fitting room door or integrated into it. The system may then determine the distance between the two tags. If they are within a threshold (e.g., about 10cm), the system may determine that the door is closed or locked; otherwise, the system may determine that the door is open or unlocked and that the fitting room is unoccupied.
In addition, the system may use a combination of position and amplitude displacement of the RFID signal to determine whether the RFID-tagged garment is on a person. For example, if a garment hangs in the air in the middle of a fitting room, it is likely to be on the body. If the RFID tag location system detects a significant drop in RSSI, accompanied by an indication (e.g., from camera data) that the RFID tag is close to the person, the user may determine that the object/clothing tagged with the RFID tag is likely to be on the person.
11.2 putting on shelf RFID tagged articles
Accurate tracking of items also allows the system to place items on shelves using autonomous vehicles (e.g., robotic devices, drones, etc.) without human intervention. For example, an RFID tag may be attached to each item, providing information about the item's desired location in the store. The autonomous vehicle may contain a tag reader to read the RFID tag and deliver the item to a desired location. The desired location (e.g., a designated shelf) may also be marked by an RFID tag (referred to as a fixture tag). In some cases, the autonomous vehicle uses its internal tag reader to locate the fixture tag and estimate the distance and direction from its current location to the fixture tag and uses the estimate to navigate towards the fixture.
In some cases, the system may monitor the location of a remotely controlled vehicle using an RFID tag on or embedded in the vehicle. The system or user may direct the vehicle toward the fixture if desired. In these cases, the vehicle may not include any tag readers.
Alternatively, the RFID tag may include identification information (e.g., a serial number) of the item, but not the expected or expected location of the item. Instead, the identification information is associated with the desired location information in the database. An RFID tag reader (e.g., on an autonomous vehicle) may read the identification information and communicate with a database to retrieve the location information.
Automatic racking may be performed with an autonomous vehicle after closing the store every night and/or before opening the store every morning. In some cases, the racking procedure is automated such that the racking procedure may be performed without human monitoring. Therefore, racking can be performed after hours to save overtime costs.
In some cases, racking may be performed as needed. For example, when the system determines that an item is in demand, the system may send a person or robot to a warehouse, pick up an item and deliver the item to a desired location. In some cases, the person or robot may also be guided to pick up the misplaced item and place it in the correct position. The system may guide the robot to the location of the misplaced item and the desired location of the item. In some cases, the RFID tag data and/or camera data may also reveal the orientation of the object and other information, such as weight, geometry, and weight distribution, to help solve complex problems such as grasping.
11.3 monitoring inventory of RFID tagged items
The system may monitor inventory of items based on accurately tracking the location of the items with RFID tags. As described above, the system may determine that an item has been picked up or is being carried by a customer, in which case the system may remove the item from the list of available items. The system may also place the item in a temporary item list that the customer considers for purchase. Once the item is checked out by the customer (e.g., in the event that the customer leaves the store with the item), the system may remove the item from the temporary list. However, if the customer changes ideas and puts the item back (or simply discards the item) before checkout, the system may put this item back on the available list.
In some cases, once the system determines that an item is under consideration by a customer, the system may interrogate RFID tags attached to the item at a frequency greater than 1Hz to track the movement of the item. After the items are returned to the shelves, the interrogation frequency may be reduced to reduce the computational burden on the system.
Employees may participate in inventory monitoring by processing defective items. Defective articles may be identified by an employee or customer. In either case, the employee may scan the RFID tag on the item using the employee device and enter the status of the item (e.g., "defective" or "damaged") into the system. The employee device may include a tag reader and an interactive interface (e.g., a touch screen) for the employee to update the inventory. In response to receiving the status, the system may remove the item from the available list and place the item in another list (e.g., a repair list or a return list). The system may also send one or more alerts to personnel associated to process defective items.
11.4 employee and product location Using RFID tag location System
The RFID tag location system may include a plurality of cameras, RFID tags, and a wireless communication system, such as bluetooth or Wi-Fi, to track the precise location of employees and products within the store. The location of the employee and product may be derived from the RFID tag location data collected by the RFID tag location system and then displayed using a GUI on a smartphone or tablet. FIG. 6 illustrates an exemplary GUI showing the location of employees and several products on a floor plan of a store. Because the RFID tag location system can identify the exact location of the employee and the product, the relative location between the employee and the product can also be displayed, as shown in fig. 6. In addition to displaying the location of the product on the floor plan, as shown in FIG. 6, the location of the product may also be displayed in a virtual tour of the store, in a 3D view of the store, or in an online shopping feature.
11.5 selecting products using GUI
As described, the GUI may display one or more products on a floor plan of the store. The GUI may also allow a user, employee, or customer to interact with the displayed product in order to perform a particular action. User interaction with the GUI may be accomplished by a number of methods, including a pointing device (e.g., a mouse), a touch-based system (e.g., a user's finger or a stylus), and so forth. For example, in a touch-based system, a user may select one or more products by drawing a shape with their finger around the products displayed in the GUI. This process is illustrated in fig. 7A to 7D. FIG. 7A shows a plurality of products displayed in the GUI. The user may use their finger to begin drawing a circular shape around multiple products, as shown in fig. 7B, until the circular shape is completed, as shown in fig. 7C. Thus, the products contained within the circular shape are selected. Prior to the user-specified action, information about the selected product, such as the number of selected products, may be displayed, as shown in fig. 7D.
Once the user selects a product, the user may then specify a number of actions to be performed on the selected product. These actions may include the following: (1) listing product details, e.g., type, color, price, size, etc., (2) listing quantity sold or value, (3) instructing the RFID reader to read only the selected product, e.g., during receipt of a new shipment, inventory taking, etc., (4) changing floor display of a particular product, (5) selecting to receive a price reminder for the selected product, (6) displaying information about similar products, (7) receiving a recommendation about similar products or updated models of the selected product, or (8) causing the selected product to be delivered or picked for purchase. Some actions may only be available to employees or customers according to their functionality.
11.6 automatic Notification of updates to inventory and new product shipments
RFID tag location systems may also be used to facilitate updating inventory when new product shipments arrive at stores. For example, a shipment may be delivered to a store from a manufacturer, a warehouse, a distribution center, or another store. To verify the number of products shipped, an RFID reader and user application may be used. The RFID reader may be optimally located in a store shipment handling area, such as a warehouse, sales area, or other location where a retailer may use to handle inbound shipments.
The products contained in the shipment may or may not contain RFID tags. For products with RFID tags, the employee may use the RFID reader and the user application to verify that the number of products received corresponds to the corresponding invoice for the product order. For products without RFID tags, employees may add RFID tags to the products and encode the appropriate product information to the tags using an RFID reader and a user application. These products can then be added before confirming the number of products received in the shipment.
Once the number of products received is verified, the RFID inventory of the products and the main enterprise inventory of the products (which may include products with and without RFID tags in multiple stores) will be updated to show the exact inventory levels of the products at the stores where the shipments were received and at the enterprise level of the multiple stores. If there is a discrepancy between the number of products received and the number of products in the invoice, the RFID tag location system may facilitate resolving the discrepancy by checking whether a product arrives in a shipment, whether an arriving product does not have an RFID tag, and whether an arriving product has an incorrect RFID tag.
Electronic notifications may also be automatically sent to customers informing them of the delivery of newly shipped products to the store. Notifications may be sent using a variety of methods, including email, text messaging, messaging applications, such as WhatsApp, Facebook messenger, geo-fencing applications, or other electronic messaging services integrated with an RFID tag location system. Notifications may be customized for priority products based on customer preferences, such as new products, best-selling products, or products for which the customer selects the notification. Notifications may also be sent to customers who previously visited a particular store, or who have subscribed to receive notifications from a particular retailer or retail location. The redirected advertisements or electronic messages may also be sent to customers who have previously visited the store but failed to purchase a particular product due to lack of availability (e.g., a preferred product does not have the desired size).
The RFID tag location system may also facilitate finding products that have lost RFID tags or products with incorrect RFID tags after delivery or during inventory checks. For example, an employee, while inspecting a pile of the same clothing, may find that the inventory level of the clothing is zero, indicating that the RFID inventory is in error due to a missing or erroneous RFID tag. In another example, an employee may be carrying a particular product and visually notice that the product lacks an RFID tag. If a product is found to have a missing RFID tag or an erroneous RFID tag after receiving and verifying a shipment, an employee may add an RFID tag to the product or replace the RFID tag of the product and use an RFID reader and user application to encode the correct product information for the tag. After encoding the new RFID tag, the RFID inventory of the product will be updated and an automatic electronic notification may be sent to the customer, as previously described.
11.7 automatic Notification of product movement and Retention
The RFID tag location system may also monitor product movement, e.g., to prioritize whether a product has not been moved to an appropriate location, such as a sales area, or to monitor product retention, e.g., a product is not set to customer retention. Based on the RFID tag location data, an electronic notification may be sent to authorized personnel, area management personnel, or business management personnel if product movement or product retention does not occur within a certain time threshold set by the retailer, e.g., 30 minutes. Notifications may be sent using a variety of methods, including email, text messaging, messaging applications, such as WhatsApp, Facebook messenger, geo-fencing applications, or other electronic messaging services integrated with an RFID tag location system.
11.8 RFID tag based product status
The RFID tag location system may also encode additional information in the RFID tag of the product. For example, RFID status tags may be used, which may include various product status and tracking information. The RFID status tags are distinguished from RFID tags in that the RFID status tags can assign the same product information to a group of RFID tags corresponding to the RFID status tags.
A variety of product states may be encoded into the RFID tag and may be based on various categories including transfer Out, e-commerce orders, and damage. In the roll-out category, the product status may include: (1) the product may be a product that is to be sent from a first store to a second store, warehouse, or distribution center, (2) the time and date of product status creation, (3) a roll-out type, e.g., a transfer to a different store, a transfer to a warehouse, a transfer to a distribution center, a transfer of damaged or recalled products, a transfer of products that require such services if cleaning or customization of the products occurs outside of the store, (3) a source of the product, e.g., a store number, (4) a destination of the product, e.g., a store number, a distribution center, a manufacturing facility number, or (5) a roll-out quantity, e.g., a tracking number created by an RFID tag location system or an existing legacy system.
In the e-commerce order category, the product status may include: (1) the goods to be sent from the store to the customer's order-designated third-party shipping address, (2) the time and date of creation of the product status, (3) the source of the goods, e.g., the store number, (4) the customer account number, e.g., an account created by an e-commerce system, (5) the e-commerce order number, e.g., an order number created by an RFID tag location system or an existing traditional e-commerce system, or (6) the e-commerce status, e.g., in-progress-the product is picked up and currently in the processing area waiting to be packaged, or packaged-has been picked up and packaged for outbound shipment.
In the damage category, the product status may include: (1) items that are currently unavailable for sale due to contamination, damage or defects, (2) the time and date of product status creation, or (3) damage transfer numbers, e.g., reference numbers created by an RFID tag location system or existing legacy systems.
The use of RFID status tags may facilitate the distribution of product status in a particular area of a store based on the location accuracy of the RFID tag location system or according to product type. For example, an RFID status tag on a particular product may automatically assign the same status to other products in its immediate vicinity, e.g., products located within 4 inches of the RFID tagged product. In another example, an RFID status tag on a particular product may assign the same status to a group of products throughout the store. The status changes for a set of products may be displayed in the GUI using different colors or symbols for those products. The visual indicator may help the employee verify the status of the product.
The RFID tag location system may also automatically alter the status of the product based on the RFID inventory of the product. For example, an RFID tagged product having a roll-out status (e.g., to another store, to a warehouse, or to a distribution center) may be considered available inventory that may fulfill an e-commerce order through the store that sent the product, as long as the store does not confirm the roll-out process. Validation may include the product being in a sealed box, the transfer of documents being completed, etc.
11.9 tracking arrival and departure routes of products
An RFID tag location system, which may include an RFID reader, a (depth) camera, and techniques to accurately determine the location of RFID tags, may be used to record the path of one or more RFID tagged products (e.g., products grouped in boxes, bags, or carts with RFID tags or RFID status tags) through a store as the products enter or exit the store. Using the user application, the path may then be displayed to the user in the GUI as an animation overlaid on the floor plan of the store, as shown in FIG. 8.
The RFID tag location system may also play back a recorded video feed of the arrival or departure of the RFID tagged product using the date, time, and location technology of the system and location data recorded by the camera as shown in fig. 8. Additionally, the RFID tag location system may also identify the individual accompanying the RFID tagged product based on facial or gait identification, the individual's bluetooth or Wi-Fi enabled device, or the user ID.
To ensure that the store is completely covered by the RFID tag positioning system, the components of the RFID tag positioning system may be mounted on the ceiling or walls, in increments of every 500 to 1000 square feet, depending on the layout and environment of the store. This enables the RFID tag location system to track all RFID tagged products and bluetooth or Wi-Fi ___33 enabled devices within the store. In addition, the system may also identify boundaries of the store, e.g., floors, rooms, entrances, exits, etc. The boundaries of the store may be marked for detection with RFID reference tags or other manual marking methods. In particular, by identifying entrances and exits, the RFID tag location system automatically registers when a product has entered or exited the store.
11.10 Intelligent, adaptive floor display of product quantity
The RFID tag positioning system may enable a user, such as an employee, to set a desired number of products, such as 12 units of products on a floor display, to be located in a particular area of a store. Further, the RFID tag location system may suggest to the user a desired placement of the product based on historical data regarding product performance in order to maximize sales. For example, a particular product may have a variety of variations, such as footwear, apparel, accessories, women's wedding dresses having different sizes. The RFID tag location system may suggest the highest performing product variant to the user for placement on the floor display of that particular store. The historical performance data may include: historical sales, number of times a customer viewed or tested a product or product variation, or conversion rate of a product or product variation, e.g., viewing versus sales, customer testing versus sales, etc.
The RFID tag location system may also dynamically modify the number and location of products in the store in real time based on inventory available at the store. For example, in table 1, an ideal scenario is shown where M and L sized products are the best performing variants, followed by S and XL sized products. Based on the user-defined requirements for the total number of products to be displayed, e.g., 12 in this example, the RFID tag positioning system automatically calculates the number of products of each size to be placed on the floor display. In this case, since the M and L sized products perform better, more M and L sized products are displayed than S and XL sized products.
TABLE 1
In another example, table 2 shows a modified scenario where the M-sized product is in short stock and therefore fails to meet the ideal floor display previously presented in table 1. In response, the RFID tag location system redistributes the number of product variations to be placed on the floor display based on the next best performing product variation. This does not necessarily display zero M-sized products, but rather reduces the number of M-sized products to accommodate available inventory and customer requirements. In this case, more L-sized products are displayed, followed by S and XL-sized products.
TABLE 2
Table 3 shows yet another modified scenario where both M and L size products are sold out and other product variants are not in sufficient inventory to meet the total number of products required. In this case, the RFID tag location system will redistribute the number of product variations to satisfy the total number of products that are displayed as better as possible while prioritizing the dimensions that represent the best.
TABLE 3
If the number of sales floor is set to zero, the RFID tag location system sets the number of products falling on the floor display to zero. Further, if at least one product is in a sales area and no product is on a floor display, a notification may be sent to the employee. This is based on a possible retailer strategy where all products available on the sales area should also be placed on the floor display. The RFID tag positioning system may also be configured to detect differences in the number of products on the sales floor and floor display, particularly to compensate for input errors of the system.
11.11 creation and optimization of picklists
As previously described, the RFID tag locating system may accurately track the number of products located in different areas of the store (e.g., sales areas or warehouses), and thus may determine which products or product variations may need to be moved to the sales area in real-time. For example, table 4 shows the distribution of product variables in the store. As shown in the table, there is an insufficient number of M and XL sized products available at the sales floor based on the number of products displayed on the floor display. As a result, two M size and one XL size product should be moved from the warehouse to the sales floor.
TABLE 4
To facilitate replenishment of a product or product variation, the RFID tag location system may immediately compile a picklist or list of requested products that require replenishment in real time. The pick-up list may then be sent to a user, e.g., a warehouse employee, who then completes the request by picking up all of the requested products and delivering the products to the sales area.
The use of pick-up lists may also be suitable for fulfilling e-commerce orders where the RFID tag location system compiles a list of products requested by the online customer to be picked up in the store. The products in the pick list may also be set to be retained by employees on behalf of the customer, by the customer using the retailer's website or application, or by customer variations of the user application. Pick lists may also be used in customer inventory requests where products are requested from the store by in-store customers through sales floor personnel, or for misplacing products where the products are placed in incorrect locations on the sales floor or in the store.
Because the RFID tag location system may track the location of a user (e.g., a warehouse employee) and the location of all products in the pick list, an Optimized Pick Path (OPP) may be generated based on the shortest time or distance that the employee picks all products. The OPP may be displayed to the user in the GUI of the user application. In fig. 9A, the OPP is shown in dashed lines, along with the location of the nearest product and user on the pick list. The OPP will be updated as the user moves, as shown in fig. 9B. When the user starts picking up a product on the pick list, the OPP will continue to update and will also display the number of products the user has picked up, as shown in fig. 9C and 9D. Also, the next product to be picked up by the user will be displayed in the GUI. OPP can also be used for e-commerce orders, customer inventory checks, and misplaced products in mobile stores or on sales areas.
If a product on the first user's pick list is picked up by a second user and delivered to a sales area, and the first user is still in the process of satisfying the request and before picking up the product, the RFID tag location system will specifically mark the product on the first user's pick list to inform the first user that the product is no longer needed. This notification process may be performed in real time using an RFID tag location system.
11.12 picklist Filter
The RFID tag location system may also enable a user to refine the pick list based on product attributes or location. For example, the user may filter the pick-up list according to a women's wedding dress,
11.13 stray product
Stray products are products that are placed in an incorrect location within the store, for example, products that are designated as being on the sales floor but are located in the warehouse. The RFID tag location system can actively and accurately track the location of specific product units, e.g., all units of a men's black V-neck T-shirt are located on a sales floor or in a warehouse. The combination of the location accuracy of the RFID tag location system and the ability to monitor all units of a particular product can enable automatic detection of stray products in the store. If stray products are detected, a notification that the product unit is in an incorrect location may be sent to the user, e.g., an employee, immediately and automatically, or after a user-defined time threshold, e.g., greater than 10 minutes.
In addition, the user application may also generate a path within the GUI that directs the user to all stray products. This path generation feature can also be used for non-stray products. For example, FIG. 10 shows a GUI for selecting a particular product within a store. The units of the selected product may not be located in the same warehouse or in the same area of a particular warehouse, for example, the units of the product may not be located within six feet of each other. In these cases, the GUI may display to the user the total number of locations that the user must access to retrieve all of the units of the product.
11.14 Intelligent routing of product notifications to Users
The location tracking features of RFID tag location systems, particularly RFID readers, user applications and systems, can be used to accurately monitor the location of a product or a variation of a product. By tracking all RFID tagged products within the store, the system can automatically notify a user, e.g., an employee, in real time whether replenishment of products is required within a particular area of the store. The threshold or criteria for product replenishment may be user determined. For example, a product may be required to have 10 units on a floor display. If initially there are 10 units of product on the floor display and the
An employee receiving a product replenishment notification may also send a request for a product to another employee, for example, a sales floor employee may request a product from an inventory employee using an internal inventory request. If the requested product is not in stock at the first store, the employee may instead use an external store request to request the product from a second store or warehouse and deliver it to the first store or customer's preferred address. This tracking feature may also be used by the customer via their mobile device using a user application to locate a particular RFID-tagged product in a store or another nearby store.
The RFID tag location system may also intelligently route inventory requests to specific employees or locations to minimize the time to deliver the requested inventory to specific areas of the store or to customers. Internal inventory requests may be routed to employees based on their proximity to the store area, customer, or warehouse, and the ability to complete tasks in a minimum amount of time. For example, employee A is processing 5 inventory requests of other customers, who must preferably fulfill these 5 inventory requests. The RFID tag location system may then route the additional request to the nearest available employee, for example, employee B, to fulfill the inventory request. Employees may also choose to turn off or mute the notification of inventory requests if an unrelated task is currently being performed. The RFID tag location system may also monitor the time it takes for an employee to complete an inventory request since the initial receipt of the inventory request to deliver a product to a customer or store area by tracking the product and employee as they move about the store.
For external inventory requests, the RFID tag location system may actively monitor and update the availability of products at multiple stores. For example, if a customer of a second store has a requested product in their shopping cart, the RFID tag location system will remove that product from the available inventory of the second store to ensure accurate information about the availability of the product to the customer of the first store. The RFID tag location system may also be used to predict the time required for an externally requested product to be delivered to a preferred address of a store or customer based on the distance between the starting location (e.g., a second store or warehouse) and the destination, as well as data detailing the speed at which inventory requests are fulfilled and transported by the starting location.
11.15 inventory request fulfillment
RFID tag location systems actively track the location of products available on the sales floor and the warehouse of the store in real time and at all times. This active tracking may facilitate employees to quickly complete a customer's inventory request. For example, a customer may use a user application to request an inventory level check of a particular product in a store. FIG. 11 illustrates an exemplary GUI in which a customer is requesting products from a warehouse for delivery to them at a sales area with an option to specify a particular product variant, e.g., a medium-sized black dress. The request may then be sent to an employee of the sales area. Employees of the sales area may then request the product requested by the customer from the store employee using the user application. The warehouse employees may then find and pick up multiple requested products for different customers. To facilitate the delivery of products to different customers of a sales area, store employees may use a user application that actively monitors the location of the different customers in real-time.
In addition to inventory requests, there may be instances where the product is misplaced or not easily found by the customer, but still exists in the sales area. The user application may provide the location of products (if present) in various areas of the store. For example, in FIG. 12, the GUI may display to the customer the location of the selected product on the sales area in addition to the quantity available in the warehouse. The user application may also enable the customer to find misplaced products on the sales area if the store's employees do not move the misplaced products.
11.16 automatic tagging of pick lists
Pick lists refer to lists of products requested by users and may include requests for internal restocking, e-commerce orders, inventory requests, misplaced products, or any other list of products that a user needs to find. The products in the pick list may be automatically marked as picked if the following conditions are met: (1) the user is using the user application to process the pick list, (2) the user picks up a product in the pick list, and (3) if a product on the user's pick list is moving with the user, the RFID/computer vision item positioning system identifies that the product is picked up by the user based on the user device or its RFID employee tag. Once these conditions are met, the RFID/computer vision item location system should automatically mark the product as it is picked by the user. To improve the accuracy of pick list auto-tagging, a threshold may be used to determine whether a product is picked by a user, such as the time after the product was picked or the distance the product has moved.
11.17 tracking high shopping cart value for customers
The RFID tag location system may also be used to actively track the number and types of products in a customer's shopping cart in real time. The shopping cart may include a basket, bag, cart, or the like. If a customer's shopping cart contains products that exceed a user-defined threshold, for example, 5 total units or $ 500 worth, a notification may be automatically sent to the employees that identify the customers. Additionally, a particular product or product category may also be flagged by the employee for preferential tracking. This tracking feature may have a variety of functional uses in the store. For example, the tracking feature may be used to prevent shoplifting by tracking products in their shopping carts that may have a large or high value or that may have selected many indicia. The tracking feature may also be used to identify customers who may be willing to spend more gold lines, which may inform employees to provide better customer service to customers, to up-sell those customers, or to recommend free products to those customers.
The RFID tag location data may be displayed to the user in various formats using a GUI in the user application. For example, an employee may view all customers within a store in the GUI and monitor their shopping carts based on the number of products or based on total value. To facilitate identification of the customer, the RFID tag location system may associate people in the store with customer profiles if the customer uses a customer variation of the user application. Otherwise, customers with products in their shopping carts may still be identified by tracking the movement of the products and determining whether the products are associated with registered employee devices.
11.18 automatically notify VIP customers
The RFID tag location system may also store data about the customer. The data may include the number of visits the customer has to the store or the amount the customer spends monthly or annually. Based on this data, the VIP title may be attributed to a customer that exceeds a user-defined threshold.
The RFID tag location system may then be used to detect and identify VIP customers and notify employees when a VIP enters a store or a particular portion of a store. Identification of the VIP may be accomplished using a variety of methods, including (1) detecting VIP status based on customer profiles stored in a user application on a customer's mobile device via bluetooth or Wi-Fi, (2) identifying a customer mobile device id based on a user application on a customer's mobile device, or (3) identifying based on facial or gait recognition using the computer vision capabilities of an RFID tag positioning system.
11.19 identification of potential product theft
As previously mentioned, the RFID tag location system may actively track the movement of products in a customer's shopping cart in real time. If an abnormal event occurs while monitoring a product, a potential theft of the product may be detected. For example, if a customer were to remove an RFID tag from a product, the RFID tag location system could detect this removal and immediately notify the employee of the exact product and its last known location in the store. Additionally, the RFID tag location system may also identify and retrieve video recordings recorded by the system's cameras or RFID readers to assist employees in locating customers or products. After this information is provided to the employee, the employee may then approach the customer to provide assistance with the product that lacks the RFID tag.
The RFID tag location system may also timestamp and store anomalous events associated with the RFID tagged product. This information can be used to display potential high theft areas to the employee in the GUI based on data such as the frequency of the RFID tags that disappear. This data may be viewed in the GUI in a user-defined time frame, e.g., the first 7 days, 30 days, 180 days, etc. In addition, the RFID tag location system may also identify and highlight areas in the store that may become highly stolen by identifying the current location of RFID tags that tend to disappear within the store.
11.20 automatic monitoring fitting room
Detection strategies similar to those used to identify potential product theft may also be used to automatically monitor fitting rooms. The RFID tag location system may track the product as it enters or leaves the fitting room. Notifications of entry or exit from the fitting room may be sent to the staff of the product in real time. If the product is left in the fitting room, the RFID tag location system may notify the employee that stray products are present in the fitting room and return the product to its correct location within the store. If the RFID tag is to be removed, resulting in the disappearance of the product in the RFID tag location system, an employee may also be sent a notification that the product may have disappeared and identify the customer with which the product was last associated. When the problematic product disappears, the customer may also be identified by other products in their shopping cart.
11.21 capture and measurement of customer and product interactions
The RFID tag location system may also be used to detect and measure data related to customer and product interactions within the store. For example, the system may track (1) how often a customer picks up products, (2) how long the customer is looking at the products, (3) which products are viewed together, (4) which products the customer is holding while viewing a new product, (5) which products may be obtained from a fitting room, (6) which products the customer interacts with before making a purchase, (7) products that may be tested by the customer, e.g., the customer fitting clothes, based on the measured distortion of the RF signal due to proximity to a body of water (e.g., a human body), (8) how long the customer tests the products. For products tested by the customer, information may also be gathered on products not purchased (e.g., clothing left in a fitting room) to assess manufacturing or fit issues, e.g., the customer prefers the appearance of a piece of clothing rather than a piece of fitted clothing. This data can be used to inform the store how to potentially modify the manufacture of the product to increase sales.
To measure these parameters, the RFID tag location system is able to track objects in 3D space with high spatial and temporal resolution. For example, the RFID tag locating system may detect whether a product has moved more than a threshold distance, e.g., 4 inches, and for a threshold period of time, e.g., more than 3 seconds. If such conditions are met, the product may be considered to be picked up or viewed by the customer.
As previously mentioned, the RFID tag location system may track the movement of products and customers within the store. The customer may be identified by: (1) the customer uses a user application on their mobile device that is detected by a bluetooth, Wi-Fi, or other wireless communication system or sensor, or (2) detects the customer by basing the customer on an individual that does not have a device or tag that is identifiable by an RFID tag location system, assuming that the employee has a tag or device.
The RFID tag location system may also collect product performance data based on product group, such as product category, subcategory, product, color, size, price range, any combination of the foregoing types, and the like. For these product groups, the performance data that can be collected includes the following: (1) the most or least viewed product group, (2) the longest or shortest viewed product group, (3) the most or least taken to fitting room product group, (4) the most or least tested or tried product group, (5) the longest or shortest time period tested or tried product group, (6) the product group with the best or worst conversion defined as the number of sales compared to the other types of data mentioned. For example, if a product is viewed 100 times a day and sold 10 times a day, the conversion is 10%. In another example, if 100 products are tried out for more than 30 seconds and sold 10, the products that are tried out for more than 30 seconds have a conversion of 10%.
Based on the product performance data collected by the RFID tag location system, improvements in store operation can be achieved by: (1) identifying the sales area in the store that performs best, (2) identifying the area where the most product interactions occur to improve staffing in that area, or (3) marketing strategies such as automatically calculating and recommending product categories based on best-selling combinations (e.g., black jeans and white T-shirts perform best together), or identifying the area of the store that is best suited for certain product types, e.g., area a dress in the store has the highest conversion rate.
Similarly, product performance data may improve a customer shopping experience by: (1) learning a customer's historical shopping preferences based on the previously defined set of products to inform the customer of new or restocked products previously searched in the store or online to the store, (2) personalizing the in-store shopping experience by highlighting products in the store or in areas of the store that may be of interest to the customer, (3) informing the customer of potential in-store promotions, or (4) identifying the customer by detecting customer profiles in a user application stored on the customer's mobile device via bluetooth or WiFi, identifying the customer mobile device id based on the user application on the customer's mobile device, or identifying the customer based on facial or gait recognition using the computer vision capabilities of an RFID tag positioning system.
11.22 conclusion
While various embodiments have been described and illustrated herein, numerous other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein are possible. More generally, all parameters, dimensions, materials, and configurations described herein are meant to be exemplary, and the actual parameters, dimensions, materials, and/or configurations will depend upon the particular application or applications for which the teachings disclosed are used. It is to be understood that the foregoing embodiments are presented by way of example only and that embodiments may be practiced otherwise than as specifically described and claimed. Embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure.
The above-described embodiments may be implemented in any of a variety of ways. For example, embodiments of the techniques disclosed herein may be implemented using hardware, software, or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers.
The various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages and/or programming or scripting tools, and may also be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine.
In this regard, the various inventive concepts may be embodied as a computer-readable storage medium (or multiple computer-readable storage media) (e.g., a computer memory, one or more floppy disks, compact disks, optical disks, tapes, flash memories, circuit configurations in field programmable gate arrays or other semiconductor devices, or other non-transitory or tangible computer storage media) encoding one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments of the inventions discussed above. The computer readable medium or media may be transportable, such that the program or programs stored thereon can be loaded onto one or more different computers or other processors to implement various aspects of the present invention as discussed above.
The terms "program" or "software" are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects of embodiments as discussed above. In addition, it should be appreciated that according to one aspect, one or more computer programs that when executed perform methods of the present invention need not reside on a single computer or processor, but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present invention.
Computer-executable instructions may take many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments.
Also, various disclosed concepts may be embodied as one or more methods, examples of which have been provided. The actions performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed which perform acts in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.
All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions incorporated by reference into a document, and/or to define the ordinary meaning of a term.
The indefinite articles "a" and "an", as used in this specification and in the claims, unless expressly specified to the contrary, should be understood to mean "at least one".
The phrase "and/or" as used in this specification and claims should be understood to mean "either or both" of the elements so joined, i.e., the elements are present in combination in some cases and are present in isolation in other cases. Multiple elements listed with "and/or" should be interpreted in the same manner, i.e., "one or more" of the elements so concatenated. In addition to elements specifically identified by the "and/or" clause, other elements may optionally be present, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "a and/or B," when used in conjunction with open-ended language (e.g., "comprises"), may refer in one embodiment to a alone (optionally including elements other than B); in another embodiment, only B (optionally including elements other than a); in yet another embodiment, refer to both a and B (optionally including other elements), and so forth.
As used in this specification and claims, "or" should be understood to have the same meaning as "and/or" as defined above. For example, when separating items in a list, "or" and/or "should be interpreted as being inclusive, i.e., including at least one but more than one of a number of elements or list of elements, and optionally including additional unlisted items. Only terms explicitly indicated to the contrary, such as "one of only … …" or "one of exactly … …," or "consisting of … …" when used in the claims, will refer to including exactly one element of a number or list of elements. In general, the term "or" as used herein when preceded by an exclusive term (such as "either," "one of … …," "only one of … …," or "just one of … …") should be construed merely to indicate an exclusive alternative (i.e., "one or the other, but not both"). "consisting essentially of … …" when used in the claims shall have the ordinary meaning as used in the patent law field.
As used herein, the terms "about" and "approximately" generally refer to plus or minus 10% of the stated value.
As used in this specification and the claims, the list phrase "at least one" referring to one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each element specifically listed in the list of elements, and not excluding any combinations of elements in the list of elements. This definition may also be such that elements other than the elements specifically identified in the list of elements to which the phrase "at least one" refers may optionally be present, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of a and B" (or, equivalently, "at least one of a or B," or, equivalently "at least one of a and/or B") can refer, in one embodiment, to at least one (optionally including more than one) a, no B (and optionally including elements other than B); in another embodiment, to at least one (optionally including more than one) B, no a is present (and optionally including elements other than a); in yet another embodiment, at least one (optionally including more than one) a, and at least one (optionally including more than one) B (and optionally including other elements), and so forth.
In the claims, as well as in the specification above, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," "consisting of," and the like are to be understood to be open-ended, i.e., to mean including but not limited to. The transition phrases "consisting of … …" and "consisting essentially of …" alone should be closed or semi-closed transition phrases, respectively, as described in the U.S. patent office patent inspection program manual, section 2111.03.
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