阅读说明：本技术 一种轮胎自定位系统及其定位方法 (Tire self-positioning system and positioning method thereof ) 是由 王旭 史卫华 韩战稳 李龙 于 2021-08-16 设计创作，主要内容包括：本发明涉及一种轮胎自定位系统及其定位方法。该轮胎自定位方法包括步骤：S1,数据采集；S2,数据转换；S3,数据统计；S4,根据统计结果判定第一信号对应的轮胎的具体位置。本发明提出了一种轮胎自定位系统及其定位方法,能提升自定位的准确性,并能克服齿数翻转引入的偏离误差问题。(The invention relates to a tire self-positioning system and a positioning method thereof. The self-positioning method of the tire comprises the following steps: s1, data acquisition; s2, data conversion; s3, data statistics; and S4, judging the concrete position of the tire corresponding to the first signal according to the statistical result. The invention provides a tire self-positioning system and a positioning method thereof, which can improve the accuracy of self-positioning and overcome the problem of deviation error caused by tooth number overturning.)

1. A method of self-positioning a tire, comprising the steps of:

s1, acquiring data, namely acquiring a wireless signal and a wired signal of the tire, wherein the wireless signal can index the corresponding time when a first signal reaches a reference point, the first signal at least comprises acceleration information of the tire, the wired signal comprises a second signal and corresponding position information of the tire, and the second signal at least comprises rotation angle information of the tire;

s2, converting data, and calculating the reference rotation angle information of the corresponding tire when the first signal reaches a reference point according to the currently received wireless signal and wired signal;

s3, carrying out data statistics, repeatedly executing steps S1 and S2, carrying out deviation degree statistics on the obtained queue of the reference rotation angle information, wherein the deviation degree statistics comprises the steps of obtaining a corresponding reference angle according to the reference rotation angle information, calculating a sine value and a cosine value of the reference angle, and carrying out variance and statistics on the accumulated sine value queue and cosine value queue;

and S4, judging the specific position of the tire corresponding to the first signal according to the statistical result.

2. The tire self-positioning method of claim 1 wherein said tire rotation angle information includes ABS tooth number of said tire rotation, said wire signal is acquired in step S1, said ABS tooth number is saved, a code value queue is generated, a plurality of said code values form a code value queue;

in step S2, calculating reference rotation angle information of the tire corresponding to the first signal reaching a reference point according to the currently received wireless signal and wired signal, and recording the reference rotation angle information as a reference encoded value;

in step S3, deviation statistics are performed on the obtained queue of the reference encoded values, where the deviation statistics include obtaining corresponding reference angles according to the reference encoded values.

3. The self-positioning method for tires according to claim 2, wherein step S3 comprises:

s31, calculating a reference angle alpha corresponding to the reference encoding value;

s32, calculating the sine value of the reference angle alpha, and carrying out variance statistics on the accumulated sine value queue; calculating a cosine value of the reference angle alpha, and carrying out variance statistics on an accumulated cosine value queue;

and S33, summing the sine variance statistics and the cosine variance statistics, wherein the sum of the variances is sine variance + cosine variance.

4. The method for self-positioning a tyre according to claim 3, wherein in step S31, said reference angle α ═ ((ABS _ ref-n)/ABS _ CODE _ MAX) × 2 Π;

where ABS _ ref is the reference CODE value and ABS _ CODE _ MAX is the number of ABS increasing teeth for one tire revolution, starting with n.

5. The method for self-positioning a tire according to claim 1, wherein said characteristic curve of said first signal is a sinusoidal curve, and a specific angle of said first signal is selected as a reference point.

6. The method for self-positioning a tire according to claim 5, wherein the highest point, the lowest point or the zero crossing point of the sinusoid of said first signal is selected as a reference point.

7. The self-positioning method for tires according to claim 2, wherein step S2 comprises:

s21, recording the time interval T1 of the currently received wireless signal and wired signal;

s22, obtaining a backtracking time T2 from the first signal reaching a reference point to the wireless signal receiving;

s23, indexing time T3 ═ backtracking time T2-time interval T1;

s24, calculating the number of code values needed to index back, wherein the number is the index time T3/the cycle ABS _ period of the second signal;

s25, according to the number of the backward index, recording the indexed encoding value ABS _ search in the encoding value queue;

and S26, correcting the code value ABS _ search, and acquiring the reference code value ABS _ ref.

8. A self-positioning system for tyres, carrying out the method for self-positioning tyres of claim 1, characterized in that it comprises:

a tire;

the tire condition detection device is arranged on the tire and used for acquiring the first signal, the pressure, the temperature and the identification code of the tire and generating the wireless signal;

the second signal sensor is arranged on the tire and used for acquiring the second signal;

the second signal controller is electrically connected with the second signal sensor, receives the second signal and generates a wired signal, and the wired signal comprises a code value corresponding to the second signal and position information of a tire where the second signal sensor is located;

a communication bus and a signal reception processor that receives the wired signal through the communication bus, receives the wireless signal, and performs steps S2 to S4 according to the wireless signal and the wired signal.

9. The tire self-positioning system of claim 8 wherein said tire condition sensing device comprises a first signal acquisition sensor for acquiring said first signal and a wireless transmission circuit through which said wireless signal is transmitted to said signal receiving processor.

10. The tire self-positioning system of claim 9 wherein said first signal acquisition sensor is an acceleration sensor and said second signal sensor is an ABS tooth pulse sensor.

Technical Field

The invention relates to the technical field of vehicle tire positioning, in particular to a tire self-positioning system and a positioning method thereof.

Background

The method has the following disadvantages that the number of ABS teeth is directly used for variance statistics in the process of tire position autonomous learning, 48-tooth ABS is taken as an example, each tooth of the ABS is uniquely coded, the number of teeth of the ABS is coded to be 0-47, and the ABS code is increased by 1 tooth when the tire rotates by 1 tooth. FIG. 1 is a diagram of ABS teeth number coding curves.

When the ABS is 1, the ABS is increased by 1 tooth, and the ABS is changed into 2; ABS exhibits a convergent characteristic.

When the ABS is 48, the ABS increases by 1 tooth, the ABS becomes 1, the difference between 48 and 1 is large, and the ABS is erroneously represented as a deviation characteristic.

Due to the fact that the tooth number codes of the ABS have the overturning characteristic, taking 48-tooth ABS as an example, the value of the ABS is 0-47;

when the ABS converges to several sets of data 10, 12, the variance value of the ABS is about 1, and the smaller the variance value, the smaller the deviation degree of the data is.

However, when the ABS converges to 47,47, 1, the variance value calculated from the above data is about 529, and the variance value is very large, indicating that the degree of deviation of the tooth number of the shuffled ABS is large. FIG. 2 is a schematic diagram showing the angle between the two sets of ABS tooth distributions with the same degree of deviation. It can be seen that the two sets of ABS have the same distribution angle, so the actual deviation of the two sets of ABS is the same.

The problem is above the code for the ABS tooth number. A solution to this problem may be to re-encode the ABS as 47,47, 49, 49 or-1, -1, 1, 1; the variance value of the ABS is corrected to 1 at this time. In view of the above problems, re-encoding is also a relatively complicated scheme, and a re-encoding rule is difficult to make, and if the encoding rule is not made properly, a large error is also introduced into the system.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a tire self-positioning system and a positioning method thereof, which can improve the self-positioning accuracy and overcome the problem of deviation error caused by tooth number overturning.

Specifically, the invention provides a tire self-positioning method, which comprises the following steps:

s1, acquiring data, namely acquiring a wireless signal and a wired signal of the tire, wherein the wireless signal can index the corresponding time when a first signal reaches a reference point, the first signal at least comprises acceleration information of the tire, the wired signal comprises a second signal and corresponding position information of the tire, and the second signal at least comprises rotation angle information of the tire;

s2, converting data, and calculating the reference rotation angle information of the corresponding tire when the first signal reaches a reference point according to the currently received wireless signal and wired signal;

s3, carrying out data statistics, repeatedly executing steps S1 and S2, carrying out deviation degree statistics on the obtained queue of the reference rotation angle information, wherein the deviation degree statistics comprises the steps of obtaining a corresponding reference angle according to the reference rotation angle information, calculating a sine value and a cosine value of the reference angle, and carrying out variance and statistics on the accumulated sine value queue and cosine value queue;

and S4, judging the specific position of the tire corresponding to the first signal according to the statistical result.

According to an embodiment of the present invention, the tire rotation angle information includes ABS tooth number of the tire rotation, the wired signal is obtained in step S1, the ABS tooth number is saved, and a queue of encoded values is generated, and a plurality of the encoded values form an encoded value queue;

in step S2, calculating reference rotation angle information of the tire corresponding to the first signal reaching a reference point according to the currently received wireless signal and wired signal, and recording the reference rotation angle information as a reference encoded value;

in step S3, deviation statistics are performed on the obtained queue of the reference encoded values, where the deviation statistics include obtaining corresponding reference angles according to the reference encoded values.

According to an embodiment of the present invention, step S3 includes:

s31, calculating a reference angle alpha corresponding to the reference encoding value;

s32, calculating the sine value of the reference angle alpha, and carrying out variance statistics on the accumulated sine value queue; calculating a cosine value of the reference angle alpha, and carrying out variance statistics on an accumulated cosine value queue;

and S33, summing the sine variance statistics and the cosine variance statistics, wherein the sum of the variances is sine variance + cosine variance.

According to an embodiment of the present invention, in the step S31, the reference angle α ═ ((ABS _ ref-n)/ABS _ CODE _ MAX) × 2 Π;

where ABS _ ref is the reference CODE value and ABS _ CODE _ MAX is the number of ABS increasing teeth for one tire revolution, starting with n.

According to one embodiment of the invention, the characteristic of the first signal is sinusoidal, a specific angle of the first signal being selected as a reference point.

According to an embodiment of the invention, the highest point, the lowest point or the zero crossing of the sinusoid of the first signal is chosen as the reference point.

According to an embodiment of the present invention, step S2 includes:

s21, recording the time interval T1 of the currently received wireless signal and wired signal;

s22, obtaining a backtracking time T2 from the first signal reaching a reference point to the wireless signal receiving;

s23, indexing time T3 ═ backtracking time T2-time interval T1;

s24, calculating the number of code values needed to index back, wherein the number is the index time T3/the cycle ABS _ period of the second signal;

s25, according to the number of the backward index, recording the indexed encoding value ABS _ search in the encoding value queue;

and S26, correcting the code value ABS _ search, and acquiring the reference code value ABS _ ref.

The invention also provides a self-positioning system for tyres for carrying out the aforesaid method for self-positioning tyres, comprising:

a tire;

the tire condition detection device is arranged on the tire and used for acquiring the first signal, the pressure, the temperature and the identification code of the tire and generating the wireless signal;

the second signal sensor is arranged on the tire and used for acquiring the second signal;

the second signal controller is electrically connected with the second signal sensor, receives the second signal and generates a wired signal, and the wired signal comprises a code value corresponding to the second signal and position information of a tire where the second signal sensor is located;

a communication bus and a signal reception processor that receives the wired signal through the communication bus, receives the wireless signal, and performs steps S2 to S4 according to the wireless signal and the wired signal.

According to one embodiment of the present invention, the tire condition detecting device includes a first signal collecting sensor for collecting the first signal and a wireless transmitting circuit through which the wireless signal is transmitted to the signal receiving processor.

According to one embodiment of the invention, the first signal acquisition sensor is an acceleration sensor and the second signal sensor is an ABS gear tooth pulse sensor.

According to the tire self-positioning system and the positioning method thereof provided by the invention, the method of performing active learning in the tire condition monitoring system by utilizing the sine variance and the cosine variance can improve the positioning success rate, the algorithm is simple, the requirement on hardware resources of a vehicle ECU is not high, and the problem of deviation error caused by tooth number inversion can be solved.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:

FIG. 1 is a diagram of ABS teeth number coding curves.

FIG. 2 is a schematic diagram showing the angle between the two sets of ABS tooth distributions with the same degree of deviation.

FIG. 3 shows a block flow diagram of a method for self-positioning a tire according to an embodiment of the present invention.

Fig. 4 shows a block flow diagram of step S3 of the self-positioning method of the tire according to one embodiment of the present invention.

Fig. 5 shows a block flow diagram of step S2 of the self-positioning method for a tire according to an embodiment of the present invention.

Fig. 6 shows a schematic structural view of a tire self-positioning system according to an embodiment of the present invention.

FIG. 7 shows an ABS tooth count diagram of an embodiment of the present invention.

FIG. 8 shows a graph of the characteristics of the first signal and the second signal for one embodiment of the present invention.

FIG. 9 shows a characteristic graph of ABS encoding and ABS variables for one embodiment of the present invention.

FIG. 10 is a characteristic graph illustrating acceleration of the first signal and ABS tooth count of the second signal in accordance with one embodiment of the present invention.

Fig. 11 shows a schematic diagram of obtaining a reference code value by indexing a second signal code value according to an embodiment of the invention.

FIG. 12 illustrates the sinusoidal characteristics and the ABS tooth count characteristics of an embodiment of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present application, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are used for convenience of description and simplicity of description only, and in the case of not making a reverse description, these directional terms do not indicate and imply that the device or element being referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore, should not be considered as limiting the scope of the present application; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of protection of the present application is not to be construed as being limited. Further, although the terms used in the present application are selected from publicly known and used terms, some of the terms mentioned in the specification of the present application may be selected by the applicant at his or her discretion, the detailed meanings of which are described in relevant parts of the description herein. Further, it is required that the present application is understood not only by the actual terms used but also by the meaning of each term lying within.

First, the design concept of the tire self-positioning method provided by the invention is briefly explained. Conventionally, a small car is taken as an example, and includes four tires, a Front Left (FL), a Front Right (FR), a Rear Right (RR), and a Rear Left (RL). After the tire condition monitoring system is mounted on each tire, it is necessary to determine the mounting position of the tire air pressure detecting device. During running of the tire, a wireless signal and a wired signal are acquired at the same reference point (the same rotation angle) of any one rotation period. The wireless signal is associated with a reference point for the acceleration signal, and the wired signal includes an ABS signal for a tooth pulse sensor of the tire and a tire position (e.g., FL) where the tooth pulse sensor is known. And calculating actual tooth number information corresponding to the reference point according to the wired signal and the wireless signal, and generating a group of tooth number information queues. For example, the wireless signal of one tire and the wired signal of the front left tire (FL), and the wired signal of the front right tire (FR), and the wired signal of the rear right tire (RR), and the wired signal of the rear left tire (RL) may form a queue of four sets of tooth number information. Based on the statistics, the set of tooth number information having the smallest deviation is determined to be the front left tire (FL) if the wired signal of the front left tire (FL) has the smallest deviation. By analogy, the actual position of each tire condition monitoring system can be confirmed, and therefore the tire position of the tire condition monitoring system can be independently learned.

FIG. 3 shows a block flow diagram of a method for self-positioning a tire according to an embodiment of the present invention. As shown in the figure, the self-positioning method of the tire provided by the invention comprises the following steps:

s1, acquiring data, namely acquiring a wireless signal and a wired signal of the tire, wherein the wireless signal can index the corresponding time when a first signal reaches a reference point, the first signal at least comprises acceleration information of the tire, the wired signal at least comprises a second signal and corresponding position information of the tire, and the second signal at least comprises rotation angle information of the tire;

s2, converting data, calculating the reference rotation angle information of the corresponding tyre when the first signal reaches the reference point according to the currently received wireless signal and wired signal;

s3, carrying out data statistics, repeatedly executing the steps S1 and S2, carrying out deviation degree statistics on the queue of the obtained reference rotation angle information, wherein the deviation degree statistics comprises the steps of obtaining a corresponding reference angle according to the reference rotation angle information, calculating a sine value and a cosine value of the reference angle, and carrying out variance and statistics on the accumulated sine value queue and cosine value queue;

and S4, judging the concrete position of the tire corresponding to the first signal according to the statistical result.

Preferably, the tire rotation angle information includes ABS tooth number of the tire rotation, the wired signal is obtained in step S1, the ABS tooth number is saved, and a queue of encoded values is generated, and the encoded values form an encoded value queue;

in step S2, calculating reference rotation angle information of the tire corresponding to the time when the first signal reaches the reference point according to the currently received wireless signal and wired signal, and recording as a reference encoded value;

in step S3, deviation statistics are performed on the obtained queue of reference encoded values, and the deviation statistics include obtaining corresponding reference angles from the reference encoded values.

Fig. 4 shows a block flow diagram of step S3 of the self-positioning method of the tire according to one embodiment of the present invention. Preferably, as shown, step S3 includes:

s31, calculating a reference angle alpha corresponding to the reference encoding value;

s32, calculating the sine value of the reference angle alpha, and carrying out variance statistics on the accumulated sine value queue; calculating a cosine value of the reference angle alpha, and carrying out variance statistics on the accumulated cosine value queue;

and S33, summing the sine variance statistics and the cosine variance statistics, wherein the sum of the variances is sine variance + cosine variance.

Preferably, in step S31, the reference angle α ═ ((ABS _ ref-n)/ABS _ CODE _ MAX) × 2 Π;

where ABS _ ref is the reference CODE value and ABS _ CODE _ MAX is the number of ABS increasing teeth for one tire revolution, the CODE value starts at n.

Preferably, the characteristic curve of the first signal is a sinusoidal curve, and a specific angle of the first signal is selected as a reference point. From the characteristic curve of the first signal, the position of a reference point is determined, which may be the highest point, the lowest point of the characteristic curve of the first signal, or the position of the tire in contact with the ground, or any other angular position. Preferably, the highest point of the sinusoid of the first signal is selected as a reference point for the data transition.

Fig. 5 shows a block flow diagram of step S2 of the self-positioning method for a tire according to an embodiment of the present invention. Preferably, step S2 includes:

s21, recording the time interval T1 of the currently received wireless signal and wired signal;

s22, obtaining the backtracking time T2 from the first signal reaching the reference point to the wireless signal receiving;

s23, indexing time T3 ═ backtracking time T2-time interval T1;

s24, calculating the number of code values needed to index back, wherein the number is the index time T3/the cycle ABS _ period of the second signal;

s25, recording the encoding value ABS _ search indexed in the queue of encoding values according to the number of the backward indexes;

s26, the encoding value ABS _ search is corrected, and the reference encoding value ABS _ ref is obtained.

Fig. 6 shows a schematic structural view of a tire self-positioning system according to an embodiment of the present invention. As shown, the present invention also provides a tire self-positioning system 600 for performing the tire self-positioning method described above. The tire self-positioning system 600 basically includes a tire 601, a tire condition detection device 602, a second signal sensor 603, a second signal controller 604, a communication bus 605 and a signal receiving processor 606.

Tire condition detection device 602 and second signal sensor 603 are provided on tire 601. The tire condition sensing device 602 is configured to collect the first signal and the pressure, temperature and identification code of the tire and generate a wireless signal.

The second signal sensor 603 is used to acquire a second signal.

The second signal controller 604 is electrically connected to the second signal sensor 603. The second signal controller 604 receives the second signal and generates a wired signal, where the wired signal includes an encoded value corresponding to the second signal and position information of the tire where the second signal sensor is located.

The signal reception processor 606 receives wired signals through the communication bus 605. The signal reception processor 606 receives wireless signals simultaneously. The signal receiving processor 606 performs steps S2 to S4 in the self-positioning method of the tire according to the wireless signal and the wired signal, and finally determines the specific position of the tire corresponding to the first signal. In an embodiment, the communication bus 605 may be a CAN communication bus.

Preferably, tire condition sensing device 602 includes a first signal acquisition sensor for acquiring a first signal and wireless transmission circuitry through which the generated wireless signal is transmitted to signal receiving processor 606. Generally, the tire condition sensing device 602 is mounted in a tire. The tire condition detection device 602 further includes a tire air pressure sensor, a temperature sensor, and the like. The tire condition detection device 602 may process the tire condition information collected by each sensor through a micro control unit integrated on a chip thereof, and simultaneously incorporate the collected tire pressure value, temperature value, etc. into a wireless signal, and simultaneously cooperate with a wireless transmitting circuit to transmit the wireless signal.

Preferably, the first signal acquisition sensor is an acceleration sensor, and the second signal sensor 603 is an ABS gear pulse sensor of an anti-lock braking system. As the tire 601 rotates, the first signal exhibits a sinusoidal characteristic. Conventionally, a vehicle is provided with a plurality of tires 601, and in the present embodiment, the vehicle has 4 tires 601, which are a front left tire (FL), a front right tire (FR), a rear right tire (RR), and a rear left tire (RL). Each tire is provided with a tire condition sensing device 602, and each tire condition sensing device 602 has a unique identifier, referred to as the ID of the tire condition sensing device 602. By way of example and not limitation, the wireless signals transmitted by the tire condition detection device 602 include an identifier, pressure, transmission time, and the like. Further, when the tire 601 rolls, the gear of the anti-lock brake system rolls along with the tire 601, and the ABS gear pulse sensor collects the number of the rotating ABS gears and sends the ABS gear information. And coding the ABS tooth number information to form a coded value. FIG. 7 shows an ABS tooth count diagram of an embodiment of the present invention. As shown, starting with the forward X-axis as the minimum CODE ABS _ CODE _ MIN, the CODE increases by 1 tooth for every 1 tooth of tire rotation counterclockwise until the CODE reaches the maximum value ABS _ CODE _ MAX after one cycle of tire rotation, after which the CODE begins again with the minimum CODE. In the embodiment, the number of teeth of the gear teeth is 48, that is, ABS _ CODE _ MIN is 0; ABS _ CODE _ MAX is 47, and tire 601 produces one pulse per tooth of rotation, so tire 601 produces 48 pulses per revolution and 96 pulses per 2 revolutions. Since the tire condition sensing device 602 and the gear at the same location are rolling along with the tire and they are coaxial, the characteristic curves of the first and second signals remain synchronized at all times. FIG. 8 shows a graph of the characteristics of the first signal and the second signal for one embodiment of the present invention. As shown, the first signal (acceleration signal) characteristic curve is shown above, and the second signal (ABS tooth code signal) characteristic curve is shown below, both synchronized.

The second signal controller 604 receives the ABS tooth number data output from the second signal sensor 603 and stores the ABS tooth number data in an accumulated form to an internal variable, which is counted again from the minimum value ABS _ MIN of the ABS variable after being accumulated to the maximum value ABS _ MAX of the ABS variable. The second signal controller 604 processes the ABS variables into a data format conforming to the bus protocol and sends them periodically onto the bus. FIG. 9 shows a characteristic graph of ABS code values and ABS variables for one embodiment of the present invention. The corresponding relation between the ABS code value and the ABS variable is as follows: ABS CODE value ═ (ABS variable)% ABS _ CODE _ MAX. For example: the value range of the ABS coded value can be 0-47; the ABS variable may range from 0 to 47.

The signal receiving processor 606 is disposed on the vehicle body side, and is configured to receive a wireless signal from each tire condition detection device 602 at any random timing. The signal receiving processor 606 receives the wired signal including the second signal, which is periodic, in this embodiment including the second signals of the four locations FL/FR/RR/RL, from the second signal controller 604.

FIG. 10 is a characteristic graph illustrating acceleration of the first signal and ABS tooth count of the second signal in accordance with one embodiment of the present invention. As shown, since the tire condition detection device 602 and the tire 601 at the same position are coaxial, the acceleration characteristic curve of the first signal from the tire condition detection device 602 at the upper side in fig. 10 and the acceleration characteristic curve of the second signal at the lower side show a synchronous law. By using this characteristic, if the reference point is selected at the same angle of the first signal characteristic curve, the corresponding coaxial second signal code values are aggregated at a specific value. The dashed position in the figure is the highest point of the sinusoid of the selected first signal as the reference point. Since the wired signal includes the position information of the tire corresponding to the second signal and the ABS tooth number information, the position of the tire condition detection device 602 can be identified by using the known position information of the second signal and the relationship between the first signal characteristic curve and the second signal characteristic curve in synchronization.

Fig. 11 shows a schematic diagram of obtaining a reference code value by indexing a second signal code value according to an embodiment of the invention. As shown, Receive _ RF is the current wireless signal received by the signal receiving processor 606, and ABS _ ref is the reference encoding value at which the first signal reaches the reference point. T2 is a trace-back time, which is the time interval from the current received radio signal Receive _ RF to the first signal reaching the reference point, and the trace-back time T2 can be included in the radio signal or obtained by calculation in the form of a time stamp. As shown in the figure, the encoded value of the second signal of the currently obtained wired signal is denoted as ABS [ n ], as a starting point, indexed back, and the reference encoded value ABS _ Ref at the reference point is calculated. The reference code value is obtained in detail as shown in fig. 5.

The corresponding reference encoded value at the reference point may be indexed by the following steps, and step S2 includes:

s21, recording the time interval T1 of the current wireless signal and wired signal reception.

S22, obtaining the backtracking time T2 from the first signal reaching the reference point to the wireless signal receiving; .

S23, the index time T3 is the trace-back time T2-time interval T1, which is the time from the reference point to the encoded value ABS [ n ] corresponding to the current wired signal.

S24, calculating the number of code values needed to index back, wherein the number is the index time T3/the period ABS _ period of the cable signal, and calculating the index value of the indexed code value queue.

S25, recording the code value ABS _ search indexed in the queue of code values according to the number of indexes back, in this example, the code value ABS _ search of the second signal is ABS [ n-2]

S26, the encoding value ABS _ search is corrected, and the reference encoding value ABS _ ref is obtained.

Specifically, step S26 includes:

s261 calculates the ABS _ period (remainder) of the period of the second signal with the index time T3% as the time interval Δ T between ABS _ search and ABS _ ref.

S262, calculate the difference between ABS _ ref and ABS _ search (ABS tooth count difference between them): Δ ABS ═ Δ T/ABS _ period (ABS [ n-2] -ABS [ n-3]), where ABS [ n-2] is the indexed coded value ABS _ search.

And S263, correcting the reference code value at the corresponding reference point, and acquiring the reference code value ABS _ ref which is ABS [ n-2] -. DELTA.ABS.

As will be readily understood, the signal reception processor 606 performs the steps S21 through S26 more than once each time it receives a wireless signal from one tire condition detection device 602, and can obtain a queue of reference code values ABS _ ref accumulated for each tire condition detection device 602. Taking 4 tires equipped with 4 tire condition detection devices 602 as an example, each tire corresponds to 4 sets of reference code value ABS _ ref data. There are 16 sets of reference code values ABS _ ref data for 4 tires. The data deviation degree is analyzed for 4 sets of reference code values ABS _ ref corresponding to each tire, and the minimum value of the sum of variances is determined to be the minimum deviation degree.

Further illustrating the deviation degree according to the variance and the statistical reference code value ABS _ ref according to fig. 3 and 4, the statistical steps are as follows:

1) a reference angle α corresponding to the reference CODE value is calculated, α ═ ((ABS _ ref-1)/ABS _ CODE _ MAX) × 2 pi. The code value of the second signal starts with 1 in this embodiment. Wherein ABS _ CODE _ MAX is the number of teeth that the ABS increases for one revolution of the gear teeth.

2) Calculating a sine value sin alpha of the deviation angle alpha, and carrying out variance statistics on an accumulated sine value queue; calculating a cosine value of the reference angle alpha, and carrying out variance statistics on the accumulated cosine value queue;

3) summing the sine variance statistic and the cosine variance statistic, wherein the sum of the variances is sine variance + cosine variance.

The variance equation:

F＝(∑(x-μ)²)/N

f is the global variance, x is the variable, mu is the global mean, and N is the global case number

The variance of sin alpha is denoted as Fsin; the variance of cos α is denoted Fcos

4) "variance and" represents the degree of deviation, which is formulated as follows:

S＝Fsin+Fcos；

the signal reception processor 606 performs a sum of variance operation on the reference code value ABS _ ref of the second signal corresponding to the same tire condition detection device 602ID, and determines the position of the tire 601 included in the second signal corresponding to the minimum "sum of variance" as the position of the tire condition detection device 602. The specific position of each tire condition detection device 602 is identified by determining all tire condition detection devices 602.

In the present embodiment, taking the reference code value sequence of 4 sets of second signals corresponding to the four tire condition detectors 602ID0 to ID3 as an example, the four sets of second signal reference code value sequences corresponding to ID0 are subjected to variance sum calculation, and the variance sum of the RR position calculated is 0.04 at the minimum, and the variance sum of the other three sets is much larger than the variance sum of the set, so that the position corresponding to the second signal reference code value with the minimum variance sum of the set is assigned to the tire condition detector 602ID 0. The specific position of each tire condition detection device 602 is identified by determining all tire condition detection devices 602.

After the position assignment of all the tire condition detecting devices is performed, it is verified whether the same tire condition detecting device is assigned to two different positions, and if not, the next verification is performed to verify whether two tire condition detecting devices 602 are assigned to the same position. And if not, determining that the tire position assignment is successful. Otherwise, waiting for the stored reference coding value queue, adding one group, and repeating the above judging process.

The time for the signal reception processor 606 to perform the tire condition ID learning process is controlled to be within 10 min. The timing condition of 10min is that the timing is started when the vehicle speed is greater than a certain threshold value, the vehicle speed threshold value of the embodiment is 35km/h, and the active learning timeout time is 8 min. If the distribution result fails according to the variance, the position of the ID is kept unchanged for the history ID, and the ID is randomly distributed to the position without the history ID for the newly added ID.

The dominance analysis using variance and statistics is as follows:

due to the fact that the stored ABS tooth number data have the tooth number overturning condition, the ABS tooth number data are considered to be converted into angle information and then are brought into a trigonometric function for calculation. The case of tooth number inversion appears as a smooth transition on the trigonometric function.

First, the tooth number is converted into angle information, and the following conversion relation can be adopted:

1) the rotation angle α ═ ((ABS _ ref-1)/ABS _ cycle) × 2 Π; v/number of teeth of the gears code from 1

2) The rotation angle α ═ ((ABS _ ref)/ABS _ cycle) × 2 Π; // number of teeth of the gears code from 0

The reference code value ABS _ ref, ABS _ cycle is the number of teeth the tooth rotates one revolution ABS increases.

After the converted angle information is brought into a sine trigonometric function, the change of the tooth number of the gear teeth in one circle and the change of the trigonometric function are compared, the situation that the numerical value jumps after the gear teeth rotate for one circle can be seen, the phenomenon is called as the overturning phenomenon of the tooth number, but the sine numerical value shows the trend of smooth change. FIG. 12 shows the sinusoidal characteristic and the ABS tooth number characteristic of an embodiment of the present invention, illustrating that the introduction of a sinusoidal function solves well for the rollover phenomenon that occurs after one revolution of the tooth number. However, the introduction of the sine curve brings a new problem, the ABS tooth number is equivalent to a unit circle, and due to the sine characteristic, the value of the first quadrant and the sine value of the second quadrant may be equal, but the tooth number value of the first quadrant and the tooth number value of the second quadrant are different, that is, different tooth numbers are equivalent to a sine function, and then the situation that different tooth numbers correspond to the same sine value occurs. This situation can lead to an inherently discrete distribution of tooth values, which is mistaken for a small degree of deviation. In order to solve the situation, a sine function is introduced and a cosine function is taken into consideration, and for the problem, when alpha is equal to pi-beta, the deviation degree of the real tooth number can be easily identified by utilizing the characteristic that the cosine function presents opposite numbers in the first quadrant and the second quadrant. In order to solve the situation, a sine function is introduced and a cosine function is taken into consideration, and for the problem, when alpha is equal to pi-beta, the deviation degree of the real tooth number can be easily identified by utilizing the characteristic that the cosine function presents opposite numbers in the first quadrant and the second quadrant. From the positive and negative of the trigonometric function in each quadrant, one can derive:

when the sine functions of the two angles are equal in the first quadrant and the second quadrant, the cosine functions are opposite numbers; when the sine functions of the two angles are equal to each other in the third quadrant and the fourth quadrant, the cosine functions are opposite numbers; when the cosine functions of the two angles are equal in the first quadrant and the fourth quadrant, the sine functions are opposite numbers; when the cosine functions of the two angles are equal in the second quadrant and the third quadrant, the sine functions are opposite numbers.

After introducing the cosine function, the influence of the sine function is eliminated by utilizing the relation that the cosine functions of two angles are opposite numbers when the sine functions of the two angles are equal to the first quadrant and the second quadrant, and the variance of the sine function and the cosine function is subjected to summation operation.

The sum of the sine and cosine variances of the FL is 0.63-0 + 0.63;

the sum of the sine and cosine variances of FR is 0.95 ═ 0.47+ 0.47;

the sum of the sine and cosine variances of RR is 0.06 to 0.05+ 0.01;

the sum of the sine and cosine variances of RL is 0.98 to 0.51+ 0.47;

	FL	FR	RR	RL
					variance of tooth number	49	225.9844	3.75	199.6875
Sum of variance	0.63	0.95	0.06	0.98

Since the sum of the variances of the RR positions is minimum, the position corresponding to the tire condition detection device 602ID0 is estimated as the rear right position (RR). And the result obtained by the variance of the tooth number is consistent.

And (3) counting the inversion of the ABS tooth number code value again by using the improved algorithm:

from the above table, it can be seen that the variance of the number of teeth at the FL position is 466.86, which is much greater than the variance of the other three sets, while the sum of the variances is 0.06, which is much less than the other three sets.

According to the tire self-positioning system and the positioning method thereof provided by the invention, the method of performing active learning in the tire condition monitoring system by utilizing the sine variance and the cosine variance can improve the positioning success rate, the algorithm is simple, the requirement on hardware resources of a vehicle ECU is not high, and the problem of deviation error caused by tooth number inversion can be solved.

It will be apparent to those skilled in the art that various modifications and variations can be made to the above-described exemplary embodiments of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.