Wheel alignment method and tire pressure monitoring system

Abstract

The present invention discloses a wheel positioning method and a tire pressure monitoring system, which obtains a compensation phase of the difference between the measured angle position of the rotation plane where the wheel is located and the fixed angle position directly reflected by the fixed magnetic value representing the wheel in the current driving direction before positioning, and determines the position of the target wheel in the vehicle according to the magnetic value, the compensation phase, and the absolute angle position of the wheel obtained from the anti-lock braking system of the vehicle. In this way, no matter in which direction the vehicle is traveling, the fixed angle position of the rotation plane where the tire pressure monitoring system is located in the current direction can be truly and correctly obtained by dynamically compensating the compensation phase, thereby realizing the function of precise positioning, that is, it can increase the robustness of judging the angle position of the tire pressure monitoring system in the rotation plane.

Description

Technical Field

[0001] The present invention relates to the field of vehicle electronics, and more particularly to a wheel positioning method and a tire pressure monitoring system. Background Art

[0002] The tire pressure monitoring system (TPMS) is a system used to monitor the internal air pressure of the wheels of various vehicles. It monitors the pressure information of the wheels through the pressure sensor (TPS) installed in the wheels and reports the pressure information to the vehicle driver. Since vehicles usually have multiple wheels, the TPMS is also required to have an automatic positioning function to inform the driver which wheel of the vehicle the current pressure information is from so that the driver can make corresponding operational responses.

[0003] The existing commonly used TPMS automatic positioning method usually includes angular position sensing (APS), which enables the TPMS to calculate the rotation angle information of the wheel in which the TPS is installed based on a set of measured acceleration measurement results received from the APS, and then compare the rotation angle information calculated by the APS with the wheel rotation derived from the sensor of the vehicle's anti-lock braking system (ABS) to obtain the positioning information of the wheel. However, in order to obtain more accurate wheel rotation angle information, this solution requires that the acceleration measurement frequency must be greater than 4 times the wheel rotation period, which will inevitably cause greater power consumption. In addition, when the wheel rotates, it vibrates due to the uneven flatness of the ground, which will add noise to the measurement results of the gravity acceleration sensor, which will make the wheel rotation information calculated by the gravity acceleration measurement results less accurate, and thus cannot achieve accurate automatic positioning of the TPMS.

[0004] In another existing TPMS automatic positioning method, a magnetometer is used to sense the magnetic force information in the environment where the wheel is located, and the relative magnetic force information is processed by mathematical operations to generate the relative magnetic force information that does not change with the geomagnetic field but changes with the rotation angle of the wheel, and the angle information related to the rotation angle of the wheel is obtained based on the relative magnetic force information, and then the rotation position information related to the rotation position of each wheel in the multiple wheels is obtained from the anti-lock braking system (ABS), and the various rotation information related to the rotation angle of each wheel in the multiple wheels is obtained based on the rotation position information, and finally the angle information is compared with the corresponding various rotation information to determine the position of the at least one wheel in the vehicle. However, this scheme does not take into account the situation that in reality, when the vehicle is traveling in different directions (east, west, south, and north), the angular position of the relative magnetic force information and the rotation plane of the wheel is not fixed, and changes with the different directions of the vehicle. Therefore, the obtained wheel angle information is not so accurate, and thus the precise automatic positioning of the TPMS cannot be achieved. Summary of the invention

[0005] In view of this, the present invention provides a wheel alignment method and a tire pressure monitoring system taking into account a compensation phase.

[0006] In a first aspect, the present invention provides a wheel alignment method, comprising:

[0007] Using the magnetic force information sensed by the magnetometer, a compensation phase of the wheel in the current driving direction is obtained, wherein the compensation phase is used to characterize the difference between the measured angular position of the wheel in the rotation plane directly reflected by the fixed magnetic value and the fixed angular position;

[0008] The magnetic force information sensed by the magnetometer is again used to generate the magnetic force value that changes with the rotation angle of the wheel after mathematical calculation by an electronic control unit, and the position of the target wheel in the vehicle is determined based on the magnetic force value, the compensation phase, and the absolute angular position of the wheel obtained from the anti-lock braking system of the vehicle.

[0009] Preferably, the value of the compensation phase changes with the change of the wheel driving direction.

[0010] Preferably, whenever the tire pressure monitoring system wakes up from a dormant state, the magnetic force information sensed by the magnetometer is acquired at a certain sampling rate to obtain the compensation phase of the wheel in the current driving direction.

[0011] Preferably, the sampling rate is positively correlated with the vehicle speed.

[0012] Preferably, a magnetic force reference value is obtained based on at least the numerical change of the corresponding magnetic force component on one axis in the magnetic force information at a predetermined sampling number or within a predetermined sampling period, and the compensation phase is obtained by querying the relationship curve based on the magnetic force reference value.

[0013] Preferably, after multiple experiments in advance, the corresponding relationship between the magnetic force reference value and the compensation phase is fitted to obtain the relationship curve.

[0014] Preferably, the fixed angle position is obtained according to the magnetic force value and the compensation phase;

[0015] Determining a position of a target wheel in the vehicle according to the fixed angle position and the absolute angle position;

[0016] The fixed angle position is obtained by adding or subtracting the compensation phase from the measured angle position of the rotation plane where the wheel is located, which is directly reflected by the magnetic force value.

[0017] Preferably, respectively obtaining the estimated rotation angle of each wheel between the first time point and the second time point, and comparing the estimated rotation angle with the absolute rotation angle of at least one wheel between the first time point and the second time point, so as to determine the position of the target wheel in the vehicle according to the matching degree;

[0018] The estimated rotation angle is the difference between the two fixed angle positions at the first time point and the second time point, and the absolute rotation angle is the difference between the two absolute angle positions at the first time point and the second time point.

[0019] Preferably, the measured angular position of the rotation plane where the wheel is located, which is directly reflected by the magnetic value, is obtained;

[0020] The position of the target wheel in the vehicle is determined according to the measured angular position and the absolute angular position at the time after the time delay corresponding to the compensation phase.

[0021] Preferably, respectively obtaining a measured rotation angle of each wheel between a first time point and a second time point, and comparing the measured rotation angle with an absolute rotation angle of at least one wheel between a third time point and a fourth time point, so as to determine the position of the target wheel in the vehicle by a matching degree;

[0022] Among them, the measured rotation angle is the difference between the two measured angle positions at the first time point and the second time point, the absolute rotation angle is the difference between the two absolute angle positions at the third time point and the fourth time point, the third time point is the moment after the first time point is delayed by the time corresponding to the compensation phase, and the fourth time point is the moment after the second time point is delayed by the time corresponding to the compensation phase.

[0023] Preferably, the absolute angular position of each wheel is obtained after the magnetic value reaches a certain value and the compensation phase is delayed for a time period corresponding to the compensation phase, and the absolute angular position is obtained again after the magnetic value reaches the value again and the compensation phase is delayed for a time period corresponding to the compensation phase.

[0024] By comparing the two absolute angular positions, the position of the target wheel in the vehicle is determined based on the degree of match.

[0025] Preferably, the mathematical operation processing includes:

[0026] The squares of the components corresponding to the axes of the magnetometer are calculated respectively, and then the squares of the components are added to obtain the magnetic value.

[0027] In a second aspect, the present invention provides a tire pressure monitoring system, characterized in that it includes:

[0028] The magnetometer located in each wheel is used to obtain the magnetic force information in the environment where the corresponding wheel is located.

[0029] The tire pressure sensor located in each wheel is used to obtain tire pressure information related to the tire pressure of the corresponding vehicle.

[0030] The electronic control unit determines the position of the target wheel in the vehicle according to the wheel positioning method, and then assigns the identification name of the tire pressure sensor to the wheel.

[0031] The present invention aims to provide a wheel alignment method and TPMS, which obtains the compensation phase of the difference between the measured angle position of the rotation plane where the wheel is located and the fixed angle position directly reflected by the fixed magnetic value representing the wheel in the current driving direction before positioning, and determines the position of the target wheel in the vehicle according to the magnetic value, the compensation phase, and the absolute angle position of the wheel obtained from the anti-lock braking system of the vehicle. In this way, no matter in which direction the vehicle is traveling, the fixed angle position of the rotation plane where the TPMS is located in the current direction can be truly and correctly obtained by dynamically compensating the compensation phase, thereby realizing the function of precise positioning, that is, it can increase the robustness of judging the angle position of the TPMS in the rotation plane. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0033] Figure 1 is a graph showing the relationship between the ideal magnetic force value according to the present invention and the rotation of the wheel;

[0034] Figure 2 A schematic diagram of the measured angular position and the actual angular position of a wheel according to the present invention;

[0035] Figure 3 A table showing the correspondence between the magnetic force reference value and the compensation phase according to the present invention;

[0036] Figure 4 FIG. 4 is a block diagram of a tire pressure monitoring system according to the present invention. DETAILED DESCRIPTION

[0037] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, some specific details are described in detail. It is possible for a person skilled in the art to fully understand the present invention without the description of these details. In order to avoid confusing the essence of the present invention, known methods, processes, flows, components and circuits are not described in detail.

[0038] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0039] At the same time, it should be understood that in the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit through electrical connection or electromagnetic connection. When an element or circuit is said to be "connected to" another element or an element / circuit is said to be "connected between" two nodes, it can be directly coupled or connected to another element or there can be an intermediate element, and the connection between the elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0040] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include", "comprising" and similar words should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0041] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0042] Figure 1 The figure is a graph showing the relationship between the ideal magnetic force value and the wheel rotation angle according to the present invention. The electronic control unit in the tire pressure monitoring system (TPMS) first generates a magnetic force value that does not change with the different directions of wheel movement but with the different wheel rotation angles after mathematical calculation based on the magnetic force information sensed by the magnetometer, and then fits the magnetic force value according to the change of the magnetic force value and the corresponding wheel rotation angle. Figure 1The ideal magnetic value shown in the figure changes with the wheel rotation angle, and the relevant information of the change relationship is saved. Here. Mathematical operation processing includes but is not limited to respectively calculating the square of each magnetic component corresponding to each axis of the magnetometer, and then adding the square of each magnetic component to obtain the magnetic value. In this way, in the subsequent process, the electronic control unit can quickly obtain how much angle the wheel rotates in a certain time period according to the change of the magnetic force information received each time. For example, at the first time point T1, the wheel rotates to the first position, and the magnetometer fixedly installed in the wheel is located directly above the wheel. At this time, the corresponding magnetic value is 1.3. At the second time T2, the magnetometer rotates to the middle position of the wheel with the rotation of the wheel. At this time, the corresponding magnetic value is 0.8. It can be seen that from the first time point T1 to the second time point T2, the variable of the magnetic value is 0.5, and the corresponding wheel rotation angle is 90 degrees. For the corresponding time points T2 and T3, the angle of wheel rotation can also be obtained in the same way. It can be seen that during the rotation of the wheel, the magnetic force value between any two time points can be obtained to calculate the wheel rotation angle between these two time points.

[0043] Preferably, in order to fit a graph showing the relationship between the magnetic value and the wheel rotation angle, in the early stage of sensing the wheel rotation, the magnetometer can be allowed to send magnetic force information to the electronic control unit multiple times (such as at least 20 times), and the electronic control unit performs a mathematical operation each time it receives the measured magnetic force information to obtain multiple magnetic values ​​corresponding to the multiple magnetic force information. The electronic control unit can then fit the above-mentioned change relationship based on the change between the multiple magnetic values ​​and the corresponding wheel rotation angle.

[0044] It should be noted that the reason why it is called Figure 1 This is an ideal relationship diagram of the change of magnetic force value with the wheel rotation angle. This is because this change relationship diagram does not take into account the situation that when the vehicle is traveling in different directions, the angular position of the magnetic force value and the rotation plane of the wheel is not fixed and changes with the different directions of the vehicle.

[0045] Experiments have found that when a vehicle is traveling in one direction, the periodic changes in the components corresponding to multiple axes of the magnetometer indicate that the magnetic distribution of one wheel rotation is periodic, and the correspondence or phase between the magnetic value and the angular position of the wheel's rotation plane is fixed; however, when the vehicle is traveling in different directions (such as east, west, south, and north), the correspondence between the magnetic value and the angular position of the wheel's rotation plane is not fixed and changes with the different directions in which the vehicle is traveling.

[0046] Figure 2The schematic diagram of the measured angular position and the real angular position of the wheel according to the present invention. Among them, the dotted line is the measured angular position of the wheel converted by the magnetic value, and the solid line is the fixed angular position of the wheel. The magnetic components on each axis in the magnetometer or the magnetic values ​​generated after mathematical operation processing have different phase differences with the fixed angular position of the rotation plane of the wheel under different driving directions of the vehicle. In other words, under different driving directions, the angular position of the magnetic component at a certain moment or the magnetic value generated after mathematical operation processing on the rotation plane of the wheel is different. Specifically, the angle of one circle of the wheel and the magnetic component or magnetic value of one circle are converted into a trigonometric function waveform, and the phase of the magnetic component or magnetic value and the fixed angle phase of the wheel are the phase difference. This phase difference is the compensation phase b that needs to be dynamically compensated under different driving directions of the vehicle.

[0047] Based on this, the present invention aims to provide a wheel alignment method, which mainly comprises the following steps:

[0048] S11: using the magnetic force information sensed by the magnetometer to obtain a compensation phase b of the wheel in the current driving direction, wherein the compensation phase b is used to characterize the difference between the measured angular position of the wheel in the rotation plane directly reflected by the fixed magnetic force value and the fixed angular position;

[0049] S12: Utilizing the magnetic force information sensed by the magnetometer again, an electronic control unit generates the magnetic force value that changes with the rotation angle of the wheel after mathematical operation, and determines the position of the target wheel in the vehicle based on the magnetic force value, the compensation phase, and the absolute angular position of the wheel obtained from the anti-lock braking system of the vehicle.

[0050] In step S11, the value of the compensation phase b changes with the change of the wheel driving direction. In order to obtain the compensation phase b, the applicant analyzed the magnetic force information of the vehicle in different driving directions and found that the magnetic force components or magnetic force values ​​of several axes of the magnetometer have a strong correlation with different driving directions, and the value of the compensation phase b that needs to be dynamically compensated is related to the driving direction. Therefore, the phase difference to be compensated can be calculated using the magnetic force component of at least one axis of the magnetometer in the current driving direction.

[0051] Preferably, whenever the tire pressure monitoring system (TPMS) wakes up from a sleep state, the magnetic force information sensed by the magnetometer can be acquired at a certain sampling rate to obtain the compensation phase b of the wheel in the current driving direction. Specifically, the sampling rate is positively correlated with the vehicle speed.

[0052] More specifically, a magnetic force reference value is obtained based on at least the numerical change of the corresponding magnetic force component on one axis in the magnetic force information at a predetermined number of sampling times or within a sampling period, and the compensation phase b is obtained by looking up the table based on the magnetic force reference value. For example, the magnetic force reference value can be obtained based on the change of the corresponding magnetic force component on the X-axis in the magnetic force information within one rotation of the wheel, or based on the change of the corresponding magnetic force component on the Y-axis, or based on the change of the calculation results obtained after the corresponding magnetic force components on multiple axes are subjected to corresponding mathematical operations. As long as the selection of the magnetic force reference value can be strongly correlated with different driving directions, in the specific implementation scheme, a parameter in the magnetic force information is selected to obtain the magnetic force reference value, which is not limited to the above examples.

[0053] Preferably, after multiple experiments, the corresponding relationship between different magnetic force reference values ​​and compensation phase b obtained by the vehicle in different driving directions can be fitted, and a relationship curve can be obtained accordingly, and the relationship curve can be written into the electronic control unit for use in subsequent steps. The relationship curve can be obtained by connecting the experimental data of some discrete test points. Figure 3 The figure is a curve of the corresponding relationship between a magnetic force reference value and a compensation phase according to the present invention, wherein the horizontal axis represents the magnetic force reference value and the vertical axis represents the compensation phase b. It can be seen from the figure that when the vehicle travels in different directions, the magnetic force reference value obtained according to the corresponding magnetic force component on the X-axis is also different, so that the compensation phase difference b corresponding to different magnetic force reference values ​​also has different values ​​or different segments.

[0054] In the first wheel positioning method provided by the present invention, a fixed angle position can be obtained based on the magnetic value and the compensation phase b; then, the position of the target wheel in the vehicle is determined based on the fixed angle position and the absolute angle position, wherein the measured angle position of the rotating plane where the wheel is located, which is directly reflected by the magnetic value, is added or subtracted from the compensation phase to obtain the fixed angle position.

[0055] Specifically, the estimated rotation angle of each wheel between the first time point and the second time point is obtained respectively, and the estimated rotation angle is compared with the absolute rotation angle of at least one wheel between the first time point and the second time point, so as to determine the position of the target wheel in the vehicle according to the matching degree. The estimated rotation angle is the difference between two fixed angle positions at the first time point and the second time point, and the absolute rotation angle is the difference between the two absolute angle positions at the first time point and the second time point.

[0056] More specifically, the measured angle position of the rotation plane where the wheel is located, which is directly reflected by the magnetic force value at the first time point and the second time point, is added or subtracted with the corresponding compensation phase to obtain two fixed angle positions, and the difference between the two fixed angle positions is the estimated rotation angle. It should be noted that the compensation phase b at the first time point and the compensation phase b at the second time point can be the same or different. During a wheel alignment process, the tire pressure monitoring system (TPMS) enters a dormant state multiple times. Whenever the tire pressure monitoring system wakes up from the dormant state, it obtains the magnetic force information sensed by the magnetometer at a certain sampling rate to obtain the latest compensation phase b of the wheel in the current driving direction. In some embodiments, the update frequency of the compensation phase can be consistent with the wheel alignment frequency, that is, in a positioning process, only one compensation phase b is obtained; in a more preferred embodiment, the compensation phase b at the first time point and the compensation phase b at the second time point are respectively selected from the latest compensation phase b obtained before the current moment and closest to the current moment, so as to improve the accuracy of wheel alignment by updating the compensation phase b in real time.

[0057] Preferably, the two tooth count information of each wheel in the plurality of wheels at the first time point and the second time point is obtained from the anti-lock braking system (ABS) respectively to obtain the fixed angle position at the first time point and the second time point, so that the difference of the two absolute angle positions between the first time point and the second time point can be obtained according to the difference of the tooth count information of the wheel tooth rotation change of each wheel in the plurality of wheels between the first time point and the second time point, so as to further obtain the absolute rotation angle. Thus, the electronic control unit in the tire pressure monitoring system can select the wheel corresponding to the absolute rotation angle that best matches or is closest to the estimated rotation angle corresponding to the target wheel as the accurate position of the target wheel.

[0058] In the second wheel positioning method provided by the present invention, the measured angular position of the rotation plane of the wheel directly reflected by the magnetic value can be obtained; then, the position of the target wheel in the vehicle is determined according to the measured angular position and the absolute angular position at the time after the time delay corresponding to the compensation phase b. Here, the time delay corresponding to the compensation phase b is the time obtained by multiplying the compensation phase b by the rotation period of the wheel.

[0059] Specifically, the measured rotation angle of each wheel between the first time point and the second time point is obtained respectively, and the measured rotation angle is compared with the absolute rotation angle of at least one wheel between the third time point and the fourth time point, so as to determine the position of the target wheel in the vehicle through the degree of matching; wherein the measured rotation angle is the difference between the two measured angle positions at the first time point and the second time point, the absolute rotation angle is the difference between the two absolute angle positions at the third time point and the fourth time point, the third time point is the moment after the first time point is delayed by the time corresponding to the compensation phase, and the fourth time point is the moment after the second time point is delayed by the time corresponding to the compensation phase.

[0060] More specifically, two measured angular positions of the rotation plane where the wheel is located are directly reflected according to the magnetic values ​​at the first time point and the second time point, and the difference between the two measured angular positions is the measured rotation angle.

[0061] Preferably, two tooth counting information of each wheel among the multiple wheels at a third time point and a fourth time point are respectively obtained from an anti-lock braking system (ABS) to obtain the absolute angular positions at the third time point and the fourth time point, so that the difference between the two absolute angular positions between the third time point and the fourth time point can be obtained according to the difference in tooth counting information of the wheel tooth rotation change of each wheel among the multiple wheels between the third time point and the fourth time point, and the difference between the two absolute angular positions between the third time point and the fourth time point can be used to further obtain the absolute rotation angle of the wheel between the first time point and the second time point.

[0062] Thus, the electronic control unit in the tire pressure monitoring system can select the wheel corresponding to the absolute rotation angle that best matches or is closest to the measured rotation angle corresponding to the target wheel as the accurate position of the target wheel.

[0063] In the third wheel alignment method provided by the present invention, the absolute angular position of each wheel is obtained after the time corresponding to the delayed compensation phase b from the moment the magnetic value reaches a certain arbitrary value or fixed value, and the absolute angular position is obtained again after the time corresponding to the delayed compensation phase from the moment the magnetic value reaches the value again, and the two absolute angular positions are compared to determine the position of the target wheel in the vehicle through the degree of matching.

[0064] Here, by comparing the errors of the two absolute angle positions of each wheel among the multiple wheels when the magnetic force value reaches the same value twice, respectively, after the time corresponding to the compensation phase b is delayed, the wheel position with the smallest error is selected as the accurate position of the target wheel. Since the magnetic force value reaches the same value twice, it can be considered that the measured rotation angles are zero degrees, so the wheel corresponding to the one with the smallest error in the two absolute angle positions after compensation is selected as the accurate position of the target wheel.

[0065] Preferably, when the magnetic value reaches a certain arbitrary value or fixed value, the electronic control unit delays the time corresponding to the corresponding compensation phase b, and then sends an RF package to the anti-lock braking system (ABS) to obtain the corresponding absolute angular position by acquiring the wheel tooth count information of each of the multiple wheels; alternatively, when the magnetic value reaches a certain arbitrary value or fixed value, the electronic control unit immediately sends the RF package to the anti-lock braking system (ABS), and the anti-lock braking system (ABS) delays the time corresponding to the corresponding compensation phase b from the moment of receiving the RF package, and then obtains the wheel tooth count information of each of the multiple wheels to obtain the corresponding absolute angular position.

[0066] As can be seen from the above, in the wheel positioning method and TPMS provided by the present invention, the compensation phase of the difference between the measured angle position of the rotation plane where the wheel is located and the fixed angle position directly reflected by the fixed magnetic value representing the wheel in the current driving direction is obtained before positioning, and the position of the target wheel in the vehicle is determined based on the magnetic value, the compensation phase, and the absolute angle position of the wheel obtained from the anti-lock braking system of the vehicle. In this way, no matter in which direction the vehicle is traveling, the fixed angle position of the rotation plane where the TPMS is located in the current direction can be truly and correctly obtained by dynamically compensating the compensation phase, thereby realizing the function of precise positioning, that is, it can increase the robustness of judging the angle position of the TPMS in the rotation plane.

[0067] In addition, if Figure 4As shown, the present invention also provides a tire pressure monitoring system (TPMS) for a vehicle, which mainly includes a plurality of magnetometers located in each wheel, the magnetometers are used to obtain the magnetic force information in the environment of each wheel, a tire pressure sensor, which is arranged in each wheel of the vehicle, and is used to obtain tire pressure information related to the tire pressure of at least one tire, and an electronic control unit TPMS_ECU, which is used to receive the magnetic force information, the tire pressure information and the absolute angle position provided by the anti-lock braking system (ABS) of the wheel, and determine which wheel among the multiple wheels the wheel comes from, and then assign the identification name of the tire pressure sensor to the wheel. The TPMS also includes a radio frequency unit RF for signal transmission with the electronic control unit TPMS_ECU, an antenna connected to the radio frequency unit RF, and a power supply unit for powering the system, such as a battery. In combination with the wheel positioning method provided by the present invention, it can be known that the tire pressure monitoring system (TPMS) provided by the present invention is a system that can realize tire pressure monitoring of the wheel and automatic positioning at the same time.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wheel alignment method, comprising: Using the magnetic force information sensed by the magnetometer, according to the corresponding relationship between the magnetic force reference value and the compensation phase, the compensation phase of the wheel in the current driving direction is obtained, the compensation phase is used to characterize the difference between the measured angular position of the rotation plane where the wheel is located and the fixed angular position directly reflected by the fixed magnetic force value, and the magnetic force reference value is obtained by at least one magnetic force component; using the magnetic force information sensed by the magnetometer again, using an electronic control unit to generate the magnetic force value that changes with the rotation angle of the wheel after mathematical operation, and determining the position of the target wheel in the vehicle according to the magnetic force value, the compensation phase, and the absolute angular position of the wheel obtained from the anti-lock braking system of the vehicle; wherein the position of the target wheel in the vehicle is determined according to the fixed angle position and the absolute angle position; or Determine the position of the target wheel in the vehicle according to the measured angular position and the absolute angular position at the time after the time delay corresponding to the compensation phase; or The absolute angular position of each wheel is obtained after a delay of a time corresponding to the compensation phase from the moment the magnetic value reaches a certain value, and the absolute angular position is obtained again after a delay of a time corresponding to the compensation phase from the moment the magnetic value reaches the value again. The position of the target wheel in the vehicle is determined by comparing the two absolute angular positions.

2. The wheel alignment method according to claim 1, characterized in that: The value of the compensation phase changes with the change of the wheel driving direction.

3. The wheel alignment method according to claim 1, characterized in that: Whenever the tire pressure monitoring system wakes up from a dormant state, the magnetic force information sensed by the magnetometer is acquired at a certain sampling rate to obtain the compensation phase of the wheel in the current driving direction.

4. The wheel alignment method according to claim 3, characterized in that: The sampling rate is positively correlated with the vehicle speed.

5. The wheel alignment method according to claim 3, characterized in that: A magnetic force reference value is obtained based on at least the value change of the corresponding magnetic force component on one axis in the magnetic force information at a predetermined sampling number or within a predetermined sampling period, and the compensation phase is obtained by querying the relationship curve based on the magnetic force reference value.

6. The wheel alignment method according to claim 5, characterized in that: After multiple experiments in advance, the corresponding relationship between the magnetic force reference value and the compensation phase is fitted to obtain the relationship curve.

7. The wheel alignment method according to claim 1, characterized in that: Obtaining the fixed angle position according to the magnetic force value and the compensation phase; The measured angular position of the wheel in the rotation plane directly reflected by the magnetic force value is added or subtracted by the compensation phase to obtain the fixed angular position.

8. The wheel alignment method according to claim 1, characterized in that: When determining the position of the target wheel in the vehicle according to the fixed angle position and the absolute angle position, respectively obtaining the estimated rotation angle of each wheel between the first time point and the second time point, and comparing the estimated rotation angle with the absolute rotation angle of at least one wheel between the first time point and the second time point to determine the position of the target wheel in the vehicle according to the degree of matching; The estimated rotation angle is the difference between the two fixed angle positions at the first time point and the second time point, and the absolute rotation angle is the difference between the two absolute angle positions at the first time point and the second time point.

9. The wheel alignment method according to claim 1, characterized in that: The measured angle position of the rotation plane where the wheel is located, which is directly reflected by the magnetic value, is obtained according to the magnetic value.

10. The wheel alignment method according to claim 9, characterized in that: Respectively obtaining a measured rotation angle of each wheel between a first time point and a second time point, and comparing the measured rotation angle with an absolute rotation angle of at least one wheel between a third time point and a fourth time point, so as to determine a position of the target wheel in the vehicle according to a matching degree; Among them, the measured rotation angle is the difference between the two measured angle positions at the first time point and the second time point, the absolute rotation angle is the difference between the two absolute angle positions at the third time point and the fourth time point, the third time point is the moment after the first time point is delayed by the time corresponding to the compensation phase, and the fourth time point is the moment after the second time point is delayed by the time corresponding to the compensation phase.

11. The wheel alignment method according to claim 1, characterized in that: When the two absolute angular positions are compared, the position of the target wheel in the vehicle is determined by the degree of match.

12. The wheel alignment method according to claim 1, characterized in that: The time corresponding to the compensation phase is the product of the compensation phase and the rotation period of the wheel.

13. The wheel alignment method according to claim 1, characterized in that: The mathematical operation processing includes: The squares of the components corresponding to the axes of the magnetometer are calculated respectively, and then the squares of the components are added to obtain the magnetic value.

14. A tire pressure monitoring system, characterized in that: include, The magnetometer located in each wheel is used to obtain the magnetic force information in the environment where the corresponding wheel is located. The tire pressure sensor located in each wheel is used to obtain tire pressure information related to the tire pressure of the corresponding vehicle. The electronic control unit determines the position of the target wheel in the vehicle according to the wheel alignment method described in any one of claims 1 to 13, and then assigns the identification name of the tire pressure sensor to the wheel.

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