Patent ID: 12208650

DETAILED DESCRIPTION

In order that the objects, aspects and advantages of the present application will become more apparent, the present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the particular embodiments described herein are illustrative only and are not limiting.

It will be appreciated that various features of the embodiments of the application can be combined with one another without departing from the scope of the application. In addition, although the division of functional blocks is illustrated in a schematic diagram of an apparatus and a logical order is illustrated in a flowchart, in some cases, it can be different from the division of functional blocks in the apparatus schematic diagram; or the steps shown or described may be performed other than that shown in the sequence of the flow chart.

Referring toFIG.1, it is a structurally schematic diagram of a wheel positioning system according to an embodiment of the present application. The system100includes an electronic control unit10, a tire pressure sensor20, and an ABS sensor30. Herein, the electronic control unit10is connected to the tire pressure sensor20and the ABS sensor30, respectively.

In the present embodiment, the positioning principle of the wheel positioning system100mainly includes that the tire pressure sensor20transmits an RF signal at one or more specific angles; after the electronic control unit10receives the RF signal, the electronic control unit10acquires information about a rotation period, a rotation angle, a tire pressure, a tire temperature, a sensor ID, etc. of the tire pressure sensor20from the RF signal. Meanwhile, the electronic control unit10acquires wheel gear pulse information from the ABS sensor30, and calculates a rotation period of the automobile wheel according to the gear pulse information. Since the tire pressure sensor20rotates integrally with the wheel at its corresponding position, the rotation period of the tire pressure sensor20is generally the same as or similar to the rotation period of the automobile wheel detected in real time. Therefore, when the rotation period of the tire pressure sensor20is the same as or similar to the rotation period of the wheel of the automobile obtained from the ABS sensor30, a target ABS sensor mounted on the same wheel as the tire pressure sensor is determined to determine the position of the same wheel from the position of the target ABS sensor.

The various modules in the system100are described in detail below based on the positioning principles of the wheel positioning system100described above.

Referring toFIG.2, it is a structural block diagram of an electronic control unit10. The electronic control unit10may include a processor101, a memory102, a receiving antenna103and a display screen104.

The processor101, the memory102, the receiving antenna103and the display screen104establish a communication connection therebetween by means of a bus or other connection.

The processor101is any type of single-threaded or multi-threaded processor having one or more processing cores as a control core of the electronic control unit10for acquiring data, performing a logical operation function and issuing an operation processing result. The processors101may be one or more, one processor101being exemplified inFIG.2.

In the present embodiment, the processor101includes a tire pressure electronic control unit (ECU)1011and an ABS control unit1012. The tire pressure ECU1011can serve as a control core of the processor101, and is used for acquiring data, performing a logical operation function and issuing an operation processing result. For example, the tire pressure ECU1011can obtain gear pulse information detected by the ABS sensor via an ABS control unit1012, and calculate a rotation period, a rotation angle and the like of the automobile wheel according to the gear pulse information. The ABS control unit1012is one of the components of an automobile Anti-lock Braking System (ABS). The basic operating principle of the ABS system is as follows: the wheel speed signals of the four wheels are collected by the rotation speed sensors mounted on the wheels and transmitted to the ABS control unit1012to calculate the wheel speed of each wheel, and then calculate the deceleration of the automobile and the slip ratio of the wheels. In the present embodiment, the ABS control unit1012is configured to acquire gear pulse information of the wheels of the automobile from the ABS sensor30and transmit the gear pulse information to the tire pressure ECU1011. The ABS control unit1012is further configured to calculate the rotation period of the automobile wheel according to the gear pulse information obtained from the ABS sensor30and transmit the rotation period of the automobile wheel to the tire pressure ECU1011.

Herein, the gear pulse information is used for indicating a relative rotational position of the wheel, which includes the obtained number of edges of the current tooth or teeth number of the ABS gear. It will be appreciated that the wheels typically have a total of 48 ABS gears, plus the clearance between the gears, which can be approximated as a total of 96 equally divided scales, each corresponding to an angle of 360/96=3.75 degrees. The ABS control unit1012may calculate the rotation angle and rotation period of the wheel according to the gear scale.

The memory102serves as a non-volatile computer-readable storage medium such as at least one disk storage device, a flash memory device, a distributed storage device remotely located with respect to the processor101, or other non-volatile solid-state storage devices. The memory102may have a program storage area to store non-volatile software programs, non-volatile computer-executable programs, and modules for invocation by processor101to cause the processor101to perform one or more method steps, for example, to perform the method steps shown inFIG.4. The memory102may also have a data storage area for storing the result of the operation processing output by the processor101.

The receiving antenna103is configured to receive the RF data transmitted by the tire pressure sensor20and transmit the RF data to the processor101, so that the processor101executes a corresponding control instruction according to the RF data. The receiving antenna103may be an RF antenna.

The display screen104is an output device for presenting corresponding data to a user in a particular form. It may be any type of display, such as a LED display, a picture tube display or an LCD display. The display screen104receives display information output by the processor101and is accordingly converted into image information to be provided to the user. For example, the display screen104may display wheel positioning result information, pressure information, temperature information, etc., so that a user can intuitively understand information about each tire through the display screen104.

It should be noted thatFIG.2is merely an example of the electronic control unit10and is not intended to limit the structure of the tire pressure sensor20.

During the wheel positioning, the tire pressure ECU1011acquires RF data transmitted from the tire pressure sensor20via the receiving antenna103, and acquires a rotation period of the tire pressure sensor20according to the RF data. The tire pressure ECU1011is further configured to obtain the current rotation period of the automobile wheel from the ABS control unit1012. Herein, the current rotation period of the automobile wheel can be calculated by the ABS control unit1012according to the gear pulse information collected by the ABS sensor30to obtain the rotation period, and the ABS control unit1012transmits the rotation period to the tire pressure ECU1011. The current rotation period of the automobile wheel may also be that the tire pressure ECU1011acquires the gear pulse information collected by the ABS sensor30via the ABS control unit1012, and then the current rotation period of the automobile wheel is calculated according to the gear pulse information. After obtaining the rotation period of the tire pressure sensor20and the current rotation period of the automobile wheel, the tire pressure ECU1011is configured to judge whether a difference value between the rotation period of the tire pressure sensor20and the current rotation period of the automobile wheel is within a preset range; if the difference value is within the preset range, a target ABS sensor mounted to the same wheel as the tire pressure sensor20is determined to determine the position of the same wheel based on the position of the target ABS sensor. After determining the ABS sensor corresponding to the wheel, the positioning of the automobile wheel can be completed according to the ABS sensor. Similarly, other wheels of the automobile may be positioned according to the method described above, wherein each wheel is provided with a tire pressure sensor20and an ABS sensor30.

Referring toFIG.3, it is a block diagram of the tire pressure sensor20. The tire pressure sensor20may include a processor201, a memory202, a timer203, an RF transmission circuit204, a pressure sensor205, an acceleration sensor206, and a temperature sensor207.

The processor201may establish a communication connection among the memory202, the timer203, the RF transmission circuit204, the pressure sensor205, the acceleration sensor206, and the temperature sensor207, respectively, via a bus or other connection.

The processor201is any type of single-threaded or multi-threaded processor having one or more processing cores as a control core of the tire pressure sensor20for acquiring data, performing a logical operation function and issuing an operation processing result. The processors201may be one or more, one processor201being exemplified inFIG.3.

The memory202serves as a non-volatile computer-readable storage medium such as at least one disk storage device, a flash memory device, a distributed storage device remotely located with respect to the processor201, or other non-volatile solid-state storage devices. The memory202may have a program storage area for storing non-volatile software programs, non-volatile computer-executable programs, and modules for invocation by processor201to cause processor201to perform one or more method steps, for example, to perform the method steps shown inFIGS.5and6. The memory202may also have a data storage area for storing the result of the operation processing output by the processor201.

The timer203is configured to periodically wake up the tire pressure sensor20. When the tire pressure sensor20is in a wake-up state, it is in an operating state; and when the tire pressure sensor20is not operating, it is in a dormant state. The tire pressure sensor20may be powered by a button battery, and the wake-up period of the timer203may be set according to a relevant parameter of the button battery.

The RF transmission circuit204is configured to transmit the RF data signal collected by the tire pressure sensor20.

The pressure sensor205, the acceleration sensor206and the temperature sensor207are respectively configured to collect pressure, acceleration and temperature data of the automobile tire.

It should be noted thatFIG.3is merely an example of the tire pressure sensor20, and is not intended to limit the structure of the tire pressure sensor20.

In the present embodiment, the tire pressure sensor20is configured to transmit an RF data signal outwardly when the rotation angle of the tire pressure sensor is a preset target angle. Specifically, the processor201is configured to acquire a rotation angle of the tire pressure sensor20, and judge whether the rotation angle is a preset target angle. If the rotation angle is the preset target angle, the processor201transmits the RF data to the electronic control unit10. Herein, the memory202can store the currently collected rotation angle information about the tire pressure sensor20, and store the preset target angle, etc.

The tire pressure sensor20may include a plurality of sensors respectively provided at positions corresponding to each tire of an automobile tire. When the automobile is provided with a spare tire, a corresponding tire pressure sensor20may also be provided for the spare tire.

The ABS sensor30is one of the components of an anti-lock braking system of the automobile. The ABS sensor30may be mounted at a corresponding position of a wheel of the automobile, and the ABS sensor30may include a plurality of sensors, for example, an ABS sensor30corresponding to a front left wheel of the automobile, an ABS sensor30corresponding to a front right wheel of the automobile, an ABS sensor30corresponding to a rear left wheel of the automobile and an ABS sensor30corresponding to a rear right wheel of the automobile. The ABS sensor30may be used to collect wheel speed signals, gear pulse information, etc. of the wheel and transmit the wheel speed signals, gear pulse information, etc. to the ABS control unit1012.

Embodiments of the present application provide a wheel positioning system that can use the existing ABS sensors30to position automobile tires, reducing automobile costs. No additional matching tools are required during the wheel positioning, reducing the threshold for wheel positioning. In addition, a step of judging a rotation period of a tire pressure sensor20and a real-time rotation period of an automobile wheel is added during positioning. Only when these two rotation periods satisfy a preset condition, a corresponding ABS sensor30thereof is determined according to the tire pressure sensor20so as to detect the position of the automobile wheel according to the determined ABS sensor30. The system can ensure the accuracy of the measurement results, and prevent the pulse counting from still being performed in case the measurement algorithm of the sensor fails or the measurement conditions are not met, resulting in positioning errors. The system improves the accuracy of wheel positioning.

It should be noted that, the wheel positioning system100performs the wheel positioning method provided by the embodiment of the present application, and has functional modules and advantageous effects corresponding to the performance of the method. Technical details not described in detail in the embodiment of the present wheel positioning system100, which may be referred to the wheel positioning method provided in the following embodiment.

Referring toFIG.4, it is a flowchart of a wheel positioning method provided by an embodiment of the present application. The method may be applied to the electronic control unit10described above, which may be mounted on an automobile including a left front wheel, a right front wheel, a left rear wheel and a right rear wheel, each wheel being provided with a tire pressure sensor20and an ABS sensor30. As shown inFIG.4, the method includes:

S101, receiving RF data from a tire pressure sensor, wherein the RF data is transmitted when a rotation angle of the tire pressure sensor20is at a target angle, and the RF data includes a rotation period of the tire pressure sensor20.

Herein, the RF data is data detected by the tire pressure sensor20. The RF data may further include a rotation angle of the tire pressure sensor20and a sensor ID which is used for identifying the tire pressure sensor20. The RF data may further include information on tire pressure, temperature, etc. of the tire detected by the tire pressure sensor20. For example, the RF data may be represented as:

SynchronousSensor IDPressureTemperatureRotationFrameRotationheadanglenumberperiodinformation

Herein, the rotation angle of the tire pressure sensor20refers to angle information corresponding to the position of the tire pressure sensor20collected at a certain sampling moment. For example, as shown inFIG.8, when the tire pressure sensor (point1) point is located at the Bottom position, the corresponding rotation angle is 270 degrees.

The rotation period of the tire pressure sensor20refers to the time difference between passing any two points that differ by 360 degrees. The rotation period of the tire pressure sensor20may be obtained according to the following modes.

Mode 1: calculating the rotation period of the tire pressure sensor20according to the formula

T=2⁢πRAcc,
where T is the rotation period of the tire pressure sensor20, R is the wheel radius, and Acc is the centripetal acceleration detected by the tire pressure sensor20.

Mode 2: determining a detection time point when the rotation angle of the tire pressure sensor20is 0 degrees and a detection time point corresponding to 360 degrees when the tire pressure sensor20rotates from 0 degrees to 360 degrees, and calculating the rotation period of the tire pressure sensor according to the detection time point corresponding to 0 degrees and the detection time point corresponding to 360 degrees. Note that, in addition to calculating the rotation period of the tire pressure sensor20based on the time taken for the tire pressure sensor to rotate from 0 degrees to 360 degrees, the rotation period of the tire pressure sensor20may be calculated based on the time taken for the tire pressure sensor20to rotate from N degrees to the next N degrees, where N is any angle between 0 degrees and 360 degrees.

Of course, in practice, the rotation period of the tire pressure sensor20may be calculated in other ways than the above two ways.

The target angle may be preset, and there is no limitation on the specific size of the target angle. It is only necessary to be able to inform the electronic control unit10in a specific manner what angle the RF signal is currently received. For example, the tire pressure sensor20alternately transmits RF signals at two fixed angles of 0° and 180°, and the odd packet data received by the electronic control unit10represents that the tire pressure sensor is at the position of 0°, and the even packet data represents that the tire pressure sensor is at the position of 180°.

S102, acquiring gear pulse information transmitted by the ABS sensor30of each wheel of the automobile, wherein the gear pulse information and the RF data are used to represent information of the wheel at approximately the same time.

S103, determining a rotation period of the wheel of the automobile from the gear pulse information of any one of the ABS sensors30of each wheel.

In the present embodiment, the electronic control unit10includes a tire pressure ECU1011and an ABS control unit1012, and the rotation period of the wheels of the automobile can be calculated by the tire pressure ECU1011itself according to the gear pulse information collected by the ABS sensor, or calculated by the ABS control unit1012according to the gear pulse information collected by the ABS sensor, and then transmitted to the tire pressure ECU1011by the ABS control unit1012.

Herein, the gear pulse information may specifically be a gear scale, and a rotation period of a wheel of the automobile may be calculated from the gear scale.

Specifically, the calculating the rotation period of the wheel of the automobile according to the gear pulse information includes: acquiring all gear scale information corresponding to a preset sampling depth, wherein the all gear scale information includes each collected gear scale and a sampling time corresponding to each gear scale; acquiring a currently collected gear scale and a first sampling time; according to the currently collected gear scale, querying the all gear scale information for a second sampling time corresponding to the same gear scale as the currently collected gear scale; andcalculating the rotation period of the wheel according to the first sampling time and the second sampling time.

For example, the sampling depth may be 1 second, i.e., the total number of scales recorded in 1 second before the current time may be saved. Assuming that the scale detected at the current moment is 60, by tracing back the time point when the last scale is 60 according to the saved total number of scales, the rotation period can be calculated according to the time point obtained by querying and the current time according to the time point obtained by querying and the current time.

It is also possible to calculate the rotation angle of the automobile wheel from the gear pulse information. Specifically, the wheels typically have a total of 48 ABS gears, plus the clearance between the gears, which can be approximated as a total of 96 equally divided scales, each corresponding to an angle of 360/96=3.75 degrees. Therefore, after obtaining the current gear scale, the rotation angle of the automobile wheel can be calculated according to the corresponding angle of each scale and the current gear scale.

S104, judging whether a difference value between the rotation period of the tire pressure sensor and the rotation period of the automobile wheel is within a preset range.

Herein, the rotation period of the wheels of the automobile determined by the gear pulse information of any one of the ABS sensors of each wheel can be respectively compared with the rotation period of the tire pressure sensor so as to find the two ABS sensors of which the rotation period is within a preset range.

As can be appreciated, since the tire pressure sensor rotates integrally with the tire, the rotation period detected by the tire pressure sensor generally coincides with the rotation period of the automobile wheel calculated from the gear pulse information. However, when the automobile travels under poor road conditions such as a sand road surface, the generated acceleration noise may cause the rotation period measured by the tire pressure sensor to be not completely consistent with the rotation period calculated from the gear pulse information, and at this time, a certain error in the detection accuracy may be allowed. Therefore, the preset range corresponding to the difference value may be zero, namely, the rotation period of the tire pressure sensor is the same as the rotation period of the automobile wheel. The preset range corresponding to the difference value may also be greater than zero and less than 1, or greater than negative one and less than zero. Namely, there is an error between the rotation period of the tire pressure sensor and the rotation period of the automobile wheel. The error is a decimal number. It should be noted that the preset range may also be other parameter ranges, without limitation.

If the difference values between the two rotation periods are within the preset range, the following step S105is performed. If the difference values of the above-mentioned two rotation periods are not within the preset range, the data detected this time may be discarded, and the above-mentioned steps S101to S103are re-executed to obtain a new rotation period parameter. Then it judges whether the difference value of the new rotation period parameter is within the preset range.

It should be noted that the ABS sensor mounted on the wheel and the ABS gear rotate integrally. Thus, theoretically, the period of one revolution of the gear measured by the ABS sensor or the wheel speed measured by the wheel speed sensor at this position is consistent with or has little deviation with the rotation period measured by the tire pressure sensor by an algorithm. However, the rotation period measured unilaterally by the tire pressure sensor may sometimes be erroneous. For example, road surface unevenness, rapid acceleration and deceleration, etc. result in that the gravitational acceleration component cannot form a sine wave; and then the position and rotation period measured by the measurement algorithm are biased. Therefore, step S104is added in the present embodiment, and it is necessary to be considered as reliable data that the rotation period measured by the tire pressure sensor is approximately consistent with the rotation period measured by the automobile itself. Thereby, the accuracy of the measurement result is ensured, and it is prevented that the pulse counting is still performed in case the tire pressure sensor measurement algorithm fails or the measurement condition is not satisfied, resulting in positioning errors.

S105, determining a target ABS sensor mounted to the same wheel as the tire pressure sensor to determine the position of the same wheel based on the position of the target ABS sensor.

The target ABS sensor is one of the above-mentioned multiple ABS sensors; the gear pulse information is detected by the target ABS sensor; the automobile wheel rotation period is calculated according to the gear pulse information; and the calculated wheel rotation period is the same as or similar to the rotation period of the tire pressure sensor.

After determining the target ABS sensor corresponding to the wheel, the wheel is positioned according to the target ABS sensor.

Here, since the position of the wheel to which the tire pressure sensor is mounted is known in advance, after the target ABS sensor is determined from the tire pressure sensor, the corresponding wheel of the target ABS sensor can be known.

According to the above-mentioned method, the ABS sensor corresponding to each wheel of the automobile can be determined separately, and then the corresponding wheel of the automobile can be positioned according to the ABS sensor. If the automobile is also equipped with a spare tire, when the rotation period of the tire pressure sensor corresponding to the spare tire and the rotation period detected by any one of the ABS sensors cannot satisfy a preset condition, the spare tire can be located according to this feature.

In some embodiments, when it is detected that the difference between the rotation period of the tire pressure sensor and the rotation period of the automobile wheel satisfies the preset range, the result may be recorded. Then it is determined whether the number of times of receiving the RF data is greater than a preset threshold. If the number of times of receiving the RF data is not greater than the preset threshold, the above-mentioned steps S101to S104are performed again, and the determination results of two rotation periods are recorded. For example, if the difference satisfies the preset range, it is recorded as 1, otherwise, it is recorded as 0. Herein, the judgement result is recorded every time after the steps S101to S104are executed, until the number of times of receiving the RF data is greater than the preset threshold value, and the steps are stopped. At this time, the result of comparing two rotation periods is analyzed, a target ABS sensor mounted on the same wheel as the tire pressure sensor is determined according to the result, and the position of the same wheel is determined according to the position of the target ABS sensor.

For example, if the judgment results of two rotation periods indicate that the two meet the preset range with 1 and that the two do not meet the preset range with 0, the number of “1” s and the number of “0” s can be counted, the tire pressure sensor and the ABS sensor corresponding to the maximum number of “1” s can be obtained, and the tire pressure sensor and the ABS sensor can be bound, so that it can be determined that the tire pressure sensor and the ABS sensor are sensors located on the same wheel, and thus the wheel positioning can be performed via the ABS sensor.

Herein, the preset threshold value can be set by the system in advance according to experience. The electronic control unit records the number of times each time the RF data is received. When the number of times the RF data is received is greater, the gear pulse information of the automobile tire obtained by the ABS sensor is greater and the positioning accuracy of the tire is higher. On the contrary, when the number of times the RF data is received is less, the gear pulse information of the automobile tire obtained by the ABS sensor is less and the positioning accuracy of the tire is lower. However, the greater the number of times RF data is received, the longer it takes for wheel positioning, and correspondingly the greater the power consumption. Therefore, the preset threshold may be set in consideration of a combination.

In other embodiments, after the step S104is performed, the gear pulse information satisfying the preset range of the rotation period difference value may also be recorded. After receiving N times of data and performing N times of rotation period comparison, a set of gear pulse information satisfying the preset range may be obtained. It determines whether the set of gear pulse information all approximately tend to a certain value. If so, a target ABS sensor mounted on the same wheel as the tire pressure sensor may be determined, thereby determining the position of the same wheel according to the position of the target ABS sensor. N is a positive integer. By multiple tests, the binding result of tire pressure sensor and ABS sensor can be more accurate, so that the final positioning result is more accurate.

For example, as shown inFIG.5, as the number of RF receptions increases, the number of data points in the figure gradually increases. The ordinate corresponding to each data point is the gear pulse count acquired by the ABS sensor, and the obtained gear pulse count gradually tends to a certain stable value. Therefore, it is known that the obtained gear pulse information of the automobile tire tends to be stable.

It will be appreciated that in a practical application scenario, there may be interference with the RF signal during transmission, resulting in the electronic control unit not being able to receive the data sent by the tire pressure sensor. Therefore, in some embodiments, the method further includes: when a data frame is lost in the received RF data, the obtained gear pulse information is synchronously matched according to the lost data frame, so that the time when the gear pulse information is obtained matches the time when the RF data is received. The method steps may be performed each time RF data is received to detect whether a data frame is lost from the received RF data.

Herein, in the data transmission process of the tire pressure sensor, each packet of RF data contains N frames of data, and a known fixed frame interval time T is used between each frame. When a frame loss occurs, the electronic control unit can perform reverse recovery according to the received frame number in the remaining frames and the frame interval time T, and perform synchronous matching by reading ABS data before the frame interval time T.

For example, as shown inFIGS.6aand6b, assuming that a packet of RF contains 3 frames of data, when a first frame in the RF data packet received by the electronic control unit is unable to be decoded due to interference, etc., the frame is judged to be lost; and when the electronic control unit receives a second frame (it can be judged that which frame is received by the frame number), the frame interval time of T1is automatically subtracted, and the ABS gear data at the moment of N1frames is read out for synchronous matching. Similarly, when frame losing appears in N1and N2transmission, the electronic control unit will automatically subtract the frame interval time of T1+T2after receiving N3, and restore the ABS gear data at the time of N1frame.

It is noted that an embodiment of the present application determines a target ABS sensor for wheel positioning according to a rotation period of a tire pressure sensor and a rotation period of an automobile wheel acquired in real time. In other embodiments, other methods may be employed to determine the target ABS sensor for wheel positioning. For example, a status flag, such as one indicating the success of the measurement, may be simply selected in place of the rotation period, and the electronic control unit may directly determine whether the measurement is valid based on the parameters of the status flag.

An embodiment of the present application provides a wheel positioning method by transmitting RF data when a tire pressure sensor rotates to a preset target angle, the RF data including a rotation period of the tire pressure sensor, determining a target ABS sensor located on the same wheel as the tire pressure sensor when the received rotation period of the tire pressure sensor is the same as the current rotation period of an automobile wheel, and then performing wheel positioning according to the target ABS sensor. In addition, frame loss prevention processing is also performed on the received RF data in the manner of a fixed frame interval and frame number, so as to ensure that the obtained RF data is accurate. This embodiment reduces tire position calibration thresholds, eliminates the need for additional mating tools, reduces automobile costs, and improves the accuracy of automobile wheel positioning.

Reference toFIG.7, it is a flowchart of a wheel positioning method provided by an embodiment of the present application. The method may be applied to the tire pressure sensor20described above, which may be provided on an automobile, such as the left front wheel, the right front wheel, the left rear wheel and the right rear wheel of the automobile, respectively. As shown inFIG.7, the method includes:

S201, waking up the tire pressure sensor periodically, acquiring the rotation angle of the tire pressure sensor when the tire pressure sensor is in a wake-up state, and determining the rotation period of the tire pressure sensor.

The tire pressure sensor is provided with a timer, and the tire pressure sensor can be woken up periodically by the timer. The tire pressure sensor is further provided with an acceleration sensor. After waking up the tire pressure sensor, the acceleration change process of the gravity component can be collected by the acceleration sensor, and the current rotation angle of the tire pressure sensor is calculated after being processed according to a preset algorithm.

Herein, the acquiring a rotation angle of the tire pressure sensor includes:obtaining the rotation angle of the tire pressure sensor according to a gravitational acceleration component of the tire pressure sensor in the X axis or the Z axis.

In this embodiment, the tangential acceleration and the normal acceleration to which the tire pressure sensor is subjected may be approximated as a constant value. During the automobile running at a constant speed, these two constant values are filtered out, namely, it can be seen that only the gravitational acceleration component changes in the X axis and Z axis, and the change process thereof is a sine wave, which is marked as X_Acc and Z_Acc respectively. For example, as shown inFIG.8, it shows the change process of the gravitational acceleration component of the tire pressure sensor in the X-axis (X_Acc) and the Z-axis (Z_Acc). Taking the Z-axis acceleration speed Z_Acc as an example, the acceleration sampling point of point1indicates that the tire pressure sensor is at the position of the tire Bottom (right below) at this time, point2indicates Back (right rear), point3indicates Top (right above), point4indicates Front (right ahead), and point5indicates Bottom (right below).

Specifically, as shown inFIG.9, the obtaining the rotation angle of the tire pressure sensor according to a gravitational acceleration component of the tire pressure sensor in the X axis or the Z axis includes:

S2011, acquiring a waveform of an X-axis gravitational acceleration component or a waveform of a Z-axis gravitational acceleration component of the tire pressure sensor.

For example, as shown inFIG.10, taking the waveform of the X-axis gravitational acceleration component as an example, the rotation angle and the rotation period of the tire pressure sensor are calculated from the X-axis gravitational acceleration component.

S2012, performing filtering processing on the obtained waveform.

In a practical application scenario, the automobile may be affected by acceleration noise caused by ground friction, automobile vibration, etc. during running. Therefore, it is necessary to filter the gravitational acceleration component superimposed with the acceleration noise.

Specifically, the performing filtering processing on the obtained waveform includes: Step one, filtering out gravitational acceleration components that exceed upper and/or lower limits to obtain a filtered first waveform.

Step 2, performing small-amplitude acceleration noise filtering processing on the first waveform.

When the automobile passes through the uneven areas such as the deceleration strip and the sunken road, the automobile will generate a large instantaneous jitter, and this large amplitude of acceleration noise has a short duration and a large component value in the whole running process. For example, as shown inFIG.11, it shows a waveform diagram of the acceleration component before first filtering. Thus, outliers that exceed the upper and/or lower limits may be “clip filtered” by filtering them as following processing algorithm:
if((Yt>Ymax)∥(Yt<Ymin))Yt-Yt-1;

t: sampling time or number of sampling times; Yt: an acceleration value acquired at a tthtime; Yt-1: an acceleration value acquired at a (t−1)thtime; Ymax: an acceleration upper limit set by the algorithm; Ymin: an acceleration lower limit set by the algorithm.

By performing clipping and filtering on the waveform of the gravitational acceleration component by the above-mentioned processing algorithm, the outliers exceeding the upper limit or/and the lower limit are filtered out, and a waveform diagram as shown inFIG.12can be obtained.

In addition, in order to conveniently map the variation trend of the gravitational acceleration component to the rotation angle of the tire pressure sensor, it is also necessary to filter the small amplitude of acceleration noise. Specifically, the “twice moving average filtering method” can be used to filter the small amplitude of acceleration noise, and the filtering algorithm is as follows:

Mt(1)=Yt+Yt-1+⋯+Yt-n+1n⁢Mt(2)=Mt(1)+Mt-1(1)+⋯+Mt-n+1(1)n

n: calculating the span of the moving average value; t: sampling time or number of times; Yt: an acceleration value acquired at a tthtime; Yt-1: an acceleration value acquired at a (t−1)thtime; Mt(1): once moving average value at a tthtime; Mt(2): twice moving average value at a tthtime.

As shown inFIG.13, a relatively smooth waveform can be obtained by processing the above-mentioned amplitude-limited filtered gravitational acceleration component according to the above-mentioned small amplitude of acceleration noise filtering processing algorithm.

The smoothed waveform is then sampled to calculate an appropriate sampling rate so as to sample the acceleration component.

S2013, calculating a sampling rate of the X-axis gravitational acceleration component or the Z-axis gravitational acceleration component after performing filtering processing, wherein the sampling rate is used for sampling the X-axis gravitational acceleration component or the Z-axis gravitational acceleration component.

The sampling rate of the X-axis gravitational acceleration component or the Z-axis gravitational acceleration component after filtering processing can be calculated according to the following formula: fsample=360°/(a*Tcircle), where fsample is a sampling rate, a is an angle measurement accuracy, i.e. the maximum angular deviation value allowed for measurement, and Tcircle is a wheel rotation period.

The value of a may be set in advance. For example a=300, and the number of points to be sampled for one revolution of the tire is X=3600/300=12, and the time required to sample a point is T=Tcircle/x, i.e. the sampling rate is fsample=1/T=x/Tcircle=360°/(a*Tcircle)=12/Tcircle. Herein, x is the number of sampling points per revolution, and T is the time required to sample a point.

It can be understood that when the sampling rate is set to be high (for example, as shown inFIG.14), the number of collected points increases, so that the original waveform can be restored more realistically. However, the storage and data processing expense of the single chip microcomputer is also increased. When the sampling rate is set low (e.g. as shown inFIG.15), the number of points collected decreases, but waveform distortion is also caused thereby. The detection accuracy decreases. Therefore, it is important to choose the appropriate sampling rate.

In this embodiment, the sampling rate may be matched to the real-time speed of the automobile to determine the appropriate sampling rate. Specifically, the method further includes: first, real-time parameters of the automobile tire are obtained, the real-time parameters including acceleration, rotation period, tire rotation speed, etc. Then the sampling rate is adjusted according to the real-time parameter. For example, current acceleration information about the automobile can be collected in real time, and an appropriate sampling rate is selected based on the acceleration, wherein the acceleration can be a centripetal acceleration. The centripetal acceleration formula is

Acc=4⁢π2⁢RTcircle2.
If it can be derived that

Tcircle=2⁢πRACC,
the sampling rate is

fsample=360⁢°a*Tcircle=360⁢°2⁢π*a⁢AccR;
where Acc is the centripetal acceleration, R is the radius of the tire, Tcircle is the rotation period of the tire, and the sampling rate fsample can be dynamically adjusted according to the centripetal acceleration. Finally, the rotation angle of the tire pressure sensor is acquired according to the adjusted sampling rate.

In addition to obtaining the sampling rate by the above method, other methods may be used to obtain the sampling rate. In some embodiments, power consumption and test efficiency issues are considered, and the single sampling time may be short (typically done in 2 S) when the automobile speed is above a certain threshold (e.g., at 40 Km/h). It can be approximately considered that the speed will not change dramatically in a short time. Therefore, according to practical applications, for example, before detecting the rotation angle, current acceleration information is collected, and then the initial setting is performed as the above sampling rate formula according to the current acceleration. During the detection, a constant sampling rate is used for detection.

S2014, converting the sampled X-axis gravitational acceleration component or the sampled Z-axis gravitational acceleration component into a rotation angle of the tire pressure sensor.

Herein, a rotation angle corresponding to the X-axis gravitational acceleration component or the Z-axis gravitational acceleration component, respectively, can be obtained with reference toFIG.8.

The determining a rotation period of the tire pressure sensor includes:calculating a rotation period of the tire pressure sensor according to a formula

T=2⁢πRAcc,wherein T is the rotation period of the tire pressure sensor, R is a wheel radius, and Acc is a centripetal acceleration detected by the tire pressure sensor; ordetermining a detection time point when the rotation angle of the tire pressure sensor is 0 degrees and a detection time point corresponding to 360 degrees when the tire pressure sensor rotates from 0 degrees to 360 degrees, and calculating the rotation period of the tire pressure sensor according to the detection time point corresponding to 0 degrees and the detection time point corresponding to 360 degrees.

The detailed process of calculating the rotation period of the tire pressure sensor may refer to the above-described embodiment, and will not be described in detail herein.

After obtaining the rotation angle of the tire pressure sensor by the above method, it is further determined whether the rotation angle is a preset target angle. The RF data is generated by the tire pressure sensor only when the preset target angle is reached.

S202, judging whether the rotation angle is a preset target angle. The preset target angle may be any angle without limitation. If the rotation angle is the preset target angle, the following step S203is executed; if the rotation angle is not the preset target angle, the following step S204is executed.

S203, transmitting RF data including a rotation period of the tire pressure sensor to an electronic control unit when the rotation angle is a preset target angle, wherein the RF data includes the rotation period of the tire pressure sensor; the rotation period is used for the electronic control unit to judge whether a difference value between the rotation period of the tire pressure sensor and the rotation period of the wheel is within a preset range; and if the difference value is within a preset range, determining the position of the wheel where the tire pressure sensor is located.

Herein, the detailed process of the electronic control unit determining whether the difference value between the rotation period and the rotation period of the wheel is within a preset range, and the detailed process of determining the position of the wheel where the tire pressure sensor is located may refer to the above-described embodiments.

S204, judging whether a detection time of the tire pressure sensor is greater than a preset time. If the detection time of the tire pressure sensor is not greater than the preset time, it skips to execute the above-mentioned step S201; if the detection time of the tire pressure sensor is greater than the preset time, the following step S205is executed.

S205, the tire pressure sensor is controlled to be in a dormant state.

Herein, if the rotation angle of the tire pressure sensor has not reached the preset target angle within a preset time, the tire pressure sensor performs a dormant state. After the tire pressure sensor wakes up next time, the above-mentioned method steps are continued to detect the rotation angle.

An embodiment of the present application provides a wheel positioning method that can be applied to a tire pressure sensor. The method includes acquiring a rotation angle of the tire pressure sensor, and when the rotation angle is a preset target angle, transiting by the tire pressure sensor the RF data to the electronic control unit, so that the electronic control unit positions an automobile tire according to the RF data. This embodiment reduces tire position calibration thresholds, eliminates the need for additional mating tools, reduces automobile costs, and improves the accuracy of wheel positioning.

Referring toFIG.16, it is a structurally schematic diagram of an automobile according to an embodiment of the present application. As shown inFIG.16, the automobile300includes the wheel positioning system100, the left front wheel310, the right front wheel320, the left rear wheel330, the right rear wheel340, and the spare tire350described by the above embodiments.

Herein, the automobile300can perform tire position positioning on the left front wheel310, the right front wheel320, the left rear wheel330, the right rear wheel340, and the spare tire350by the wheel positioning system100.

The automobile300may be various types of automobiles, for example, passenger cars, commercial cars, etc. Embodiments of the present application provide an automobile that does not require additional tools for wheel positioning, has the advantages of low operational thresholds and low cost, and provides reliable and accurate wheel positioning results.

Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the present application, rather than limiting it. Combinations of features in the above embodiments or in different embodiments are also possible within the spirit of the application. The steps can be implemented in any order, and there are many other variations of the different aspects of the application described above, which are not provided in detail for the sake of brevity. Although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art will appreciate that the technical solutions of the each above-mentioned embodiment can still be modified, or some of the technical features thereof can be equivalently substituted; and such modifications and substitutions will not cause the essence of the corresponding technical solutions to depart from the scope of the embodiments of the application.