阅读说明：本技术 一种控制车辆减速的方法及装置 (Method and device for controlling vehicle deceleration ) 是由 柯建成 熊振 饶兵 张小刚 陈迎燕 于 2021-07-29 设计创作，主要内容包括：本发明涉及车辆控制技术领域,尤其涉及一种控制车辆减速的方法及装置,该方法应用于设置在限速路段周围的智能减速设备中,该方法包括：获取车辆的当前速度,该车辆为要经过限速路段的车辆；基于该车辆的当前速度,确定车辆的减速区域,减速区域为车辆由当前速度减速至限速路段的限速时所行驶的路程区域；在检测到车辆进入减速区域时,控制车辆由当前速度开始减速,使得车辆在进入限速路段时满足限速,且按照该限速通过限速路段,进而通过自动监测和控制的方式控制车辆按照限速通过限速路段,以确保车辆行驶安全性,降低了在限速路段中由司机主动控制车速时带来的安全隐患。(The invention relates to the technical field of vehicle control, in particular to a method and a device for controlling vehicle deceleration, wherein the method is applied to intelligent deceleration equipment arranged around a speed-limiting road section, and comprises the following steps: acquiring the current speed of a vehicle, wherein the vehicle is a vehicle passing through a speed-limiting road section; determining a deceleration area of the vehicle based on the current speed of the vehicle, wherein the deceleration area is a distance area which is driven when the vehicle decelerates from the current speed to the speed limit of the speed-limit road section; when the vehicle is detected to enter the deceleration area, the vehicle is controlled to start to decelerate from the current speed, so that the vehicle meets the speed limit when entering the speed limit road section, and passes through the speed limit road section according to the speed limit, and then the vehicle is controlled to pass through the speed limit road section according to the speed limit in an automatic monitoring and controlling mode, so that the driving safety of the vehicle is ensured, and the potential safety hazard caused when the vehicle speed is actively controlled by a driver in the speed limit road section is reduced.)

1. A method for controlling vehicle deceleration is applied to intelligent deceleration equipment arranged around a speed-limited road section, and is characterized by comprising the following steps:

acquiring the current speed of a vehicle, wherein the vehicle is a vehicle passing through a speed-limiting road section;

determining a deceleration area of the vehicle based on the current speed of the vehicle, wherein the deceleration area is a distance area which is driven when the vehicle decelerates from the current speed to the speed limit of the speed-limit road section;

and when the vehicle is detected to enter the deceleration area, controlling the vehicle to start decelerating from the current speed, so that the vehicle meets the speed limit when entering the speed limit road section, and passing through the speed limit road section according to the speed limit.

2. The method of claim 1, wherein upon detecting the vehicle entering the deceleration zone, controlling the vehicle to begin decelerating from the current speed such that the vehicle satisfies the speed limit upon entering the speed limit segment and after traversing the speed limit segment at the speed limit, further comprising:

and controlling the vehicle to recover to the speed before deceleration from the speed limit.

3. The method of claim 1, prior to said obtaining a current speed of the vehicle, further comprising:

judging whether the vehicle passes through a speed-limiting road section;

and if so, executing the step of acquiring the current speed of the vehicle.

4. The method of claim 1, wherein determining a deceleration zone for a vehicle based on a current speed of the vehicle, the deceleration zone being a range zone where the vehicle is speed limited from the current speed to the speed-limited route segment, comprises:

acquiring the speed limit of the speed limit road section and the set acceleration of the vehicle;

and determining a deceleration area of the vehicle based on the speed limit, the current speed and the set acceleration, wherein the deceleration area is a distance area for the vehicle to decelerate to the speed limit of the speed limit road section from the current speed.

5. The method of claim 1, wherein the speed limit section is a fixed section or a variable section.

6. The method of claim 1, wherein when the speed-limited section is a fixed section, the speed-limited section is any one of: traffic light intersection, school doorway, front of bus station, road turning, bridge.

7. The method of claim 1, wherein when the speed-limit section is a variable section, the speed-limit section is a speed-limit section set based on a time period; or a speed-limited section set based on the congestion condition.

8. The utility model provides a device for controlling vehicle speed reduction, is applied to and sets up in the intelligent deceleration equipment around the speed limit highway section, its characterized in that includes:

the acquisition module is used for acquiring the current speed of a vehicle, wherein the vehicle is a vehicle passing through a speed-limiting road section;

the determining module is used for determining the length of a deceleration area of the vehicle based on the current speed of the vehicle, wherein the deceleration area is a distance area for the vehicle to decelerate to the speed-limited road section from the current speed;

and the control module is used for controlling the vehicle to start to decelerate from the current speed when detecting that the vehicle enters the deceleration area, so that the vehicle meets the speed limit when entering the speed limit road section, and passes through the speed limit road section according to the speed limit.

9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method steps of any of claims 1-7 when executing the program.

10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the method steps of any one of claims 1 to 7.

Technical Field

The invention relates to the technical field of vehicle control, in particular to a method and a device for controlling vehicle deceleration.

Background

When the existing vehicle passes through a speed-limiting road section, the driver is forced to decelerate autonomously by reminding the user, or by adding a deceleration strip on the road surface.

However, drivers sometimes ignore the reminding board of the speed-limiting road section, so that overspeed driving is caused, and potential safety hazards are brought; the deceleration strip forces the mode that the driver slows down to make driver's experience relatively poor, also often has the condition that the driver does not slow down and forces to pass through in addition, also can bring the potential safety hazard.

Therefore, how to reduce the potential safety hazard of the speed-limited road section is a technical problem to be solved urgently at present.

Disclosure of Invention

In view of the above, the present invention has been made to provide a method and apparatus for controlling deceleration of a vehicle that overcomes or at least partially solves the above problems.

In a first aspect, the present invention provides a method for controlling vehicle deceleration, applied to an intelligent deceleration device arranged around a speed-limited road section, comprising:

acquiring the current speed of a vehicle, wherein the vehicle is a vehicle passing through a speed-limiting road section;

determining a deceleration area of the vehicle based on the current speed of the vehicle, wherein the deceleration area is a distance area which is driven when the vehicle decelerates from the current speed to the speed limit of the speed-limit road section;

and when the vehicle is detected to enter the deceleration area, controlling the vehicle to start decelerating from the current speed, so that the vehicle meets the speed limit when entering the speed limit road section, and passing through the speed limit road section according to the speed limit.

Further, when it is detected that the vehicle enters the deceleration area, controlling the vehicle to start decelerating from the current speed, so that the vehicle meets the speed limit when entering the speed limit road section, and after passing the speed limit road section according to the speed limit, the method further includes:

and controlling the vehicle to recover to the speed before deceleration from the speed limit.

Further, before the obtaining the current speed of the vehicle, the method further includes:

judging whether the vehicle passes through a speed-limiting road section;

and if so, executing the step of acquiring the current speed of the vehicle.

Further, the determining a deceleration area of the vehicle based on the current speed of the vehicle, where the deceleration area is a distance area where the vehicle decelerates from the current speed to the speed-limited road segment, includes:

acquiring the speed limit of the speed limit road section and the set acceleration of the vehicle;

and determining a deceleration area of the vehicle based on the speed limit, the current speed and the set acceleration, wherein the deceleration area is a distance area for the vehicle to decelerate to the speed limit of the speed limit road section from the current speed.

Further, the speed-limiting road section is a fixed road section or a variable road section.

Further, when the speed-limiting road section is a fixed road section, the speed-limiting road section is any one of the following: traffic light intersection, school doorway, front of bus station, road turning, bridge.

Further, when the speed-limiting road section is a variable road section, the speed-limiting road section is set based on a time period; or a speed-limited section set based on the congestion condition.

In a second aspect, the present invention further provides a device for controlling vehicle deceleration, which is applied to an intelligent deceleration device arranged around a speed-limited road section, and comprises:

the acquisition module is used for acquiring the current speed of a vehicle, wherein the vehicle is a vehicle passing through a speed-limiting road section;

the determining module is used for determining the length of a deceleration area of the vehicle based on the current speed of the vehicle, wherein the deceleration area is a distance area for the vehicle to decelerate to the speed-limited road section from the current speed;

and the control module is used for controlling the vehicle to start to decelerate from the current speed when detecting that the vehicle enters the deceleration area, so that the vehicle meets the speed limit when entering the speed limit road section, and passes through the speed limit road section according to the speed limit.

In a third aspect, the present invention also provides a computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the above-mentioned method steps when executing the program.

In a fourth aspect, the present invention also provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the above method steps.

One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

the invention provides a method for controlling vehicle deceleration, which is applied to intelligent deceleration equipment arranged around a speed-limited road section and comprises the following steps: acquiring the current speed of a vehicle, wherein the vehicle is a vehicle passing through a speed-limiting road section; determining a deceleration area of the vehicle based on the current speed of the vehicle, wherein the deceleration area is a distance area which is driven when the vehicle decelerates from the current speed to the speed limit of the speed-limit road section; when the vehicle is detected to enter the deceleration area, the vehicle is controlled to start to decelerate from the current speed, so that the vehicle meets the speed limit when entering the speed limit road section, and passes through the speed limit road section according to the speed limit, and then the vehicle is controlled to pass through the speed limit road section according to the speed limit in an automatic monitoring and controlling mode, so that the driving safety of the vehicle is ensured, and the potential safety hazard caused when the vehicle speed is actively controlled by a driver in the speed limit road section is reduced.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a flow chart illustrating the steps of a method of controlling deceleration of a vehicle in an embodiment of the present invention;

FIG. 2 shows a schematic diagram of a deceleration zone in an embodiment of the invention;

FIG. 3 shows a schematic diagram of a recovery area in an embodiment of the invention;

FIG. 4 is a schematic configuration diagram showing an apparatus for controlling deceleration of a vehicle in the embodiment of the invention;

fig. 5 is a schematic structural diagram of a computer device for implementing the method for controlling deceleration of a vehicle in the embodiment of the present invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

Example one

The embodiment of the invention provides a method for controlling a vehicle to decelerate, which can control the speed of the vehicle to be within a speed-limiting range when the vehicle passes through a speed-limiting road section, thereby effectively reducing the potential safety hazard of the vehicle on the speed-limiting road section. The method is applied to intelligent speed reduction equipment arranged around a speed-limiting road section. The intelligent speed reducing device can realize information interaction with the vehicle. The intelligent speed reducing equipment is arranged around different speed limiting road sections.

As shown in fig. 1, the method includes:

s101, acquiring the current speed of a vehicle, wherein the vehicle is a vehicle passing through a speed-limited road section;

s102, determining a deceleration area of the vehicle based on the current speed of the vehicle, wherein the deceleration area is a distance area which is driven when the vehicle decelerates from the current speed to the speed limit of the speed-limit road section;

s103, when the vehicle is detected to enter the deceleration area, the vehicle is controlled to start to decelerate from the current speed, so that the vehicle meets the speed limit when entering the speed limit road section, and passes through the speed limit road section according to the speed limit.

In an optional implementation manner, before S101, the method further includes: judging whether the vehicle passes through the speed-limiting road section; if yes, S101 is performed.

First, the information about whether the vehicle should pass through the speed-limited road section can be obtained through the information transmission of the internet of vehicles according to the navigation information of the vehicle.

Secondly, the information whether the vehicle passes through the speed-limiting road section can be obtained according to the driving route of the vehicle shot by the camera.

Thirdly, a preset range can be defined for the speed-limiting road section, and when the vehicle enters the preset range, the vehicle is determined to pass through the speed-limiting road section. The determination of whether the vehicle will pass through the speed-limited section is not limited herein.

After determining that the vehicle is to pass through the speed-limited section, S101 is executed to acquire a current speed of the vehicle, which is the vehicle to pass through the speed-limited section.

The current speeds of all vehicles passing through the speed-limiting road section can be obtained through the internet of vehicles. The speed of the vehicle can be directly obtained through a speedometer and then obtained through the Internet of vehicles; the current speed may also be sent by each vehicle through the internet of vehicles, which is not limited herein.

Next, S102 is executed to determine a deceleration area of the vehicle based on the current speed of the vehicle, where the deceleration area is a route area where the vehicle travels when decelerating from the current speed to the speed limit of the speed-limited road segment.

Specifically, the speed limit of a speed-limit road section and the set acceleration of a vehicle are acquired; based on the speed limit, the current speed, and the set acceleration, a deceleration zone of the vehicle is determined.

The vehicle may be preset with acceleration, for example 20km/h²It can also set 30km/h². Since the speed limit of the speed-limited road section is known, the current speed is known, and therefore the time t taken by the vehicle to decelerate from the current speed to the speed limit can be obtained.

Based on the speed limit v_tCurrent speed v₀And setting the acceleration a, so that the distance L traveled by the vehicle when the vehicle decelerates from the current speed to the speed limit can be obtained, and the distance is the shortest length of the deceleration area.

L＝(v_t ²-v₀ ²)/2a

Of course, the length of the deceleration area is the shortest length L, and may be greater than the length L, which is not limited herein.

A schematic of this deceleration region is shown in figure 2.

After the deceleration area is determined, S103 is executed, and when the vehicle is detected to enter the deceleration area, the vehicle is controlled to start decelerating from the current speed, so that the vehicle meets the speed limit when entering the speed limit road section, and passes through the speed limit road section according to the speed limit.

Before S103, the length of the speed limit section and the speed limit need to be broadcasted to the vehicle that is going to pass through the speed limit section, specifically, according to the protocol of the whole internet of vehicles, the length is compiled into a code, for example, 000 means that the speed limit is 10km/h, and 001 means that the speed limit is 20km/h, wherein the setting is performed by taking 10km/h as one level, for the length, 20m is taken as one level, for example, the last three levels are compiled into a code 000, which means that the distance is 20m, and if the compiled code is 001, the distance is 40m, which is not limited herein.

The information is uniformly broadcast through the cloud server to remind nearby vehicles of paying attention, so that the vehicles which need to pass through the speed-limiting road section know the speed and the passing length which need to be limited.

After the vehicle knows the speed limit and the length to be passed, the vehicle needs to be controlled to start decelerating through the intelligent deceleration device.

Therefore, it is necessary to detect whether the vehicle enters the deceleration area, and the detection may be performed by a camera, or may be performed by a distance sensor disposed around, which is not limited herein. Then, the detected result is sent to the intelligent speed reduction device.

Then, S103 is executed, and when it is detected that the vehicle enters the deceleration area, the vehicle is controlled to start decelerating from the current speed, so that the vehicle meets the speed limit when entering the speed limit road section, and passes through the speed limit road section according to the speed limit.

In S103, there are two control processes:

the first control process: and controlling the vehicle to start decelerating from the current speed when the vehicle enters the deceleration area. Since the deceleration zone is already determined, the vehicle must reach the speed limit at the end of the travel in the deceleration zone.

And the second control process is that when the vehicle enters the speed-limiting road section, the vehicle is controlled to pass through the speed-limiting road section according to the speed limit.

The speed-limiting road section can be a fixed road section or a variable road section.

When the speed-limiting road section is a fixed road section, the speed-limiting road section is any one of the following: traffic light intersection, school doorway, front of bus station, road turning, bridge. Of course, other places where the speed limit sign is fixedly arranged may be also possible, and the place is not limited herein.

When the speed-limit section is a variable section, the speed-limit section is a speed-limit section set based on a time period or a speed-limit section set based on a congestion condition.

And when the speed-limiting road section is a fixed road section, the detection of the speed-limiting road section is started all the day. When the speed-limiting road section is a variable road section, the speed-limiting road section is detected to be opened according to time or according to a detected people flow result. Thereby flexibly starting the control time of the speed-limiting road section.

When the human flow is detected, the detection can be carried out by a thermal imager arranged around the thermal imager, and when the detection result of the thermal imager indicates that the human flow reaches a preset value, the speed-limiting road section is controlled to be opened; and when the detection result of the thermal imager indicates that the human flow does not reach the preset value, the speed-limiting road section is not opened, namely the road section is a common road section.

After the vehicle leaves from the speed-limited road section, the method comprises the following steps: and controlling the vehicle to recover to the speed before deceleration, namely the current speed from the speed limit.

Specifically, the vehicle is controlled to return from the speed limit to the speed before deceleration in accordance with a set acceleration of the vehicle, which may be in accordance with the set accelerationThe magnitude of the acceleration at the time of deceleration in the deceleration section may be the same or different, and if the user urgently needs to restore the vehicle speed to the previous speed, the acceleration may be set to be large, for example, 30km/h²(ii) a If the user is not anxious to return the vehicle speed to the previous speed, the control can be performed according to the previous acceleration, but a smaller acceleration, such as 10km/h, can be set²And is not limited thereto. Therefore, the section traveled at the speed before the speed of the control vehicle is returned from the speed limit to the deceleration is a return section, the length of which is determined in accordance with the set acceleration, as shown in fig. 3 in particular.

One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

the invention provides a method for controlling vehicle deceleration, which is applied to intelligent deceleration equipment arranged around a speed-limited road section and comprises the following steps: acquiring the current speed of a vehicle, wherein the vehicle is a vehicle passing through a speed-limiting road section; determining a deceleration area of the vehicle based on the current speed of the vehicle, wherein the deceleration area is a distance area which is driven when the vehicle decelerates from the current speed to the speed limit of the speed-limit road section; when the vehicle is detected to enter the deceleration area, the vehicle is controlled to start to decelerate from the current speed, so that the vehicle meets the speed limit when entering the speed limit road section, and passes through the speed limit road section according to the speed limit, and then the vehicle is controlled to pass through the speed limit road section according to the speed limit in an automatic monitoring and controlling mode, so that the driving safety of the vehicle is ensured, and the potential safety hazard caused when the vehicle speed is actively controlled by a driver in the speed limit road section is reduced.

Example two

Based on the same inventive concept, the present invention also provides a device for controlling vehicle deceleration, which is applied to an intelligent deceleration device arranged around a speed-limited road section, as shown in fig. 4, and comprises:

the acquiring module 401 is configured to acquire a current speed of a vehicle, where the vehicle is a vehicle that will pass through a speed-limited road segment;

the determining module 402 is configured to determine a length of a deceleration area of a vehicle based on a current speed of the vehicle, where the deceleration area is a distance area where the vehicle decelerates from the current speed to the speed-limited road segment to limit the speed;

the control module 403 is configured to, when it is detected that the vehicle enters the deceleration area, control the vehicle to start decelerating from the current speed, so that the vehicle meets the speed limit when entering the speed-limit road segment, and passes through the speed-limit road segment according to the speed limit.

In an optional embodiment, the method further comprises: a second control module to:

and controlling the vehicle to recover to the speed before deceleration from the speed limit.

In an optional embodiment, the method further comprises:

a judging module: the speed limiting device is used for judging whether the vehicle passes through a speed limiting road section or not; the step of acquiring the current speed of the vehicle is performed.

In an alternative embodiment, the determining module 402 includes:

the acquisition unit is used for acquiring the speed limit of the speed-limit road section and the set acceleration of the vehicle;

and the determining unit is used for determining a deceleration area of the vehicle based on the speed limit, the current speed and the set acceleration, wherein the deceleration area is a distance area for the vehicle to decelerate from the current speed to the speed limit of the speed limit road section.

In an alternative embodiment, the speed-limiting section is a fixed section or a variable section.

In an alternative embodiment, when the speed-limited section is a fixed section, the speed-limited section is any one of the following: traffic light intersection, school doorway, front of bus station, road turning, bridge.

In an alternative embodiment, when the speed-limit section is a variable section, the speed-limit section is a speed-limit section set based on a time period; or a speed-limited section set based on the congestion condition.

EXAMPLE III

Based on the same inventive concept, the embodiment of the present invention provides a computer device, as shown in fig. 5, including a memory 504, a processor 502 and a computer program stored on the memory 504 and operable on the processor 502, wherein the processor 502 implements the steps of the method for controlling deceleration of a vehicle described above when executing the program.

Where in fig. 5 a bus architecture (represented by bus 500) is shown, bus 500 may include any number of interconnected buses and bridges, and bus 500 links together various circuits including one or more processors, represented by processor 502, and memory, represented by memory 504. The bus 500 may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. A bus interface 506 provides an interface between the bus 500 and the receiver 501 and transmitter 503. The receiver 501 and the transmitter 503 may be the same element, i.e. a transceiver, providing a means for communicating with various other apparatus over a transmission medium. The processor 502 is responsible for managing the bus 500 and general processing, and the memory 504 may be used for storing data used by the processor 502 in performing operations.

Example four

Based on the same inventive concept, embodiments of the present invention provide a computer-readable storage medium having stored thereon a computer program, which, when executed by a processor, performs the steps of the above-described method of controlling deceleration of a vehicle.

The algorithms and displays presented herein are not inherently related to any particular computer, virtual machine, or other apparatus. Various general purpose systems may also be used with the teachings herein. The required structure for constructing such a system will be apparent from the description above. Moreover, the present invention is not directed to any particular programming language. It is appreciated that a variety of programming languages may be used to implement the teachings of the present invention as described herein, and any descriptions of specific languages are provided above to disclose the best mode of the invention.

In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.

The various component embodiments of the invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It will be appreciated by those skilled in the art that a microprocessor or Digital Signal Processor (DSP) may be used in practice to implement some or all of the functions of some or all of the components of the apparatus, computer device, for controlling vehicle deceleration according to embodiments of the present invention. The present invention may also be embodied as apparatus or device programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present invention may be stored on computer-readable media or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.