Adaptive wheel speed decoding method and system based on AK protocol

Abstract

The invention relates to a self-adaptive wheel speed decoding method and system based on an AK protocol. The method comprises the following steps: S1, acquiring a Tp interval of a current data frame; s2, calculating a sampling position based on the Tp interval; carrying out multiple times of sampling based on the sampling position; determining a judgment sampling group based on the sampling result, and determining a judgment result of the judgment sampling group; and S3, determining a current data bit value based on judgment results of the first sampling group and the second sampling group. According to the invention, the decoding information in the wheel speed detection process can be adaptively processed, so that the decoding bit width change caused by external factors in the actual use process can be better identified, the decoding accuracy is improved, and the problem of possible decoding failure of Manchester decoding can be early warned in advance.

Description

Technical Field

[0001] The invention belongs to the technical field of wheel speed decoding, and in particular relates to an AK protocol-based adaptive wheel speed decoding method and system. Background Art

[0002] Wheel speed sensors are a vital component of modern cars. The wheel speed information they provide is usually used in systems that affect the safety performance of the car, such as anti-lock braking systems, electronic stability systems, and vehicle dynamic control systems. Currently, intelligent wheel speed sensors with data protocols and verification functions are becoming more and more widely used. The most common and commonly used ones are wheel speed sensors based on the AK communication protocol. The AK protocol (usually referred to as Automobil-Kommunikation, or a private protocol defined by a specific manufacturer) is a protocol used for communication between vehicle electronic control units (ECUs), commonly found in CAN (Controller Area Network) or FlexRay or PSI5 bus systems.

[0003] The AK protocol transmits data by controlling the magnitude of the current. The AK protocol wheel speed sensor is a Hall-type wheel speed sensor that uses the Hall effect principle to generate wheel speed. Usually, there are three Hall elements on its chip, consisting of two Hall elements placed longitudinally on the left and right and another Hall element placed horizontally between them. The magnetic induction intensity of the three Hall elements can be recorded as B1, B2, and B3 respectively, and then the speed and direction signals are obtained through different differential calculations: the speed signal is calculated by B2-B1; the direction signal is calculated by B3-(B1+B2) / 2. At the same time, the AK protocol is also a way for the controller and the wheel speed sensor to communicate. The AK signal transmits data by controlling the magnitude of the current. A frame of the AK signal contains a speed pulse and a data protocol bit, which correspond to the speed signal and the data signal respectively. Its data frame structure: contains an identifier (ID), a data length (DLC), and a data field (Data Field), in which the wheel speed information is usually encoded in a specific byte of the data field. In terms of real-time performance, it supports the rapid transmission of high-priority messages and is suitable for high-frequency update signals such as wheel speed. In terms of fault tolerance, the reliability of data transmission is generally ensured through CRC check, bit filling and other technologies. Signal acquisition and preprocessing are required before decoding; sensor pulse signals are captured through CAN controller or direct IO. Then an adaptive digital filter (such as Kalman filter or sliding average filter) is used to eliminate high-frequency noise while retaining the dynamic characteristics of the signal. Then signal shaping is performed to convert the analog pulse into a digital square wave for subsequent processing.

[0004] One frame of AK signal contains speed pulse and data protocol bit, which correspond to speed signal and data signal respectively. Speed ​​pulse signal is high current (ICCH) level, and data signal is medium current (ICCM) level. There are three main working modes. Figure 1 As shown, Figure 1 The waveform of the signal in normal mode is shown. In normal working mode: when the sensor detects a zero-crossing input signal, that is, the magnetic induction intensity is 0, a speed pulse is output after a certain delay (usually 70 to 121 us), and the time length of the speed pulse is the Tp interval. The time synchronization mechanism (such as Sync message) of the AK protocol is used to align the speed data of each wheel. The data of multiple sensors are fused through Kalman filtering or weighted average algorithm to improve robustness. Due to the great differences in the environment in which the vehicle is located, the working conditions of the decoder are also changing. In particular, in actual use, the data width varies greatly. The commonly used decoding method only samples in a fixed manner and is not sensitive to changes in data width. It is very likely that inaccurate sampling will lead to decoding failure in extreme cases, which may lead to decoding errors, thereby posing a hidden danger to vehicle safety; exception handling and fault tolerance are very important in adaptive wheel speed decoding based on the AK protocol. If no valid pulse is received for multiple consecutive cycles, the signal loss will trigger fault diagnosis; in addition, the traditional static threshold control process cannot automatically adjust the threshold level of pulse recognition according to environmental conditions, which is also a common situation that causes abnormalities. Based on the above problems, the present invention adaptively adjusts the decoding information in the wheel speed detection process through dynamic Tp interval estimation, so as to better identify the changes in decoding bit width caused by external factors in actual use and perform accurate pulse data acquisition, thereby improving the reliability of detection and vehicle safety, and can dynamically adapt to changes in working conditions while saving on-chip resources to the greatest extent. Summary of the invention

[0005] In order to solve the above problems in the prior art, the present invention proposes a method and system for adaptive wheel speed decoding based on AK protocol, the method comprising: Step S02: when the first pulse arrives, record the current timestamp and the timestamp of the falling edge to calculate the width of the speed pulse, and write the width into the first storage space as the estimated Tp interval; Step S1: Reading Tp interval from the first storage space; Step S2: Calculate the actual sampling point based on the Tp interval; oversample the data frame based on the sampling point and determine the value of each data bit; specifically includes the following steps: Step S21: setting a correspondence table between Tp intervals and sampling points, and obtaining an oversampling ratio corresponding to the current Tp interval by querying the correspondence table; Step S22: Continuously sample at the sampling rate and use the sampling count value to count; equal the sampling count value to The sampling result at 1000 is taken as the second sampling group. The sampling result at that time is taken as the first sampling group; the first sampling group and the second sampling group are judged within the group using the best-of-three system. When two of the three sampling results in the sampling group are greater than or equal to 1, the judgment result of the sampling group is 1; otherwise, the judgment result is 0; Step S3: Determine the current data bit value based on the judgment results of the first sampling group and the second sampling group; determine whether the judgment results of the first sampling group and the second sampling are equal; if they are equal, determine that the sampled data is incorrect, if the judgment result of the first sampling group is 0, and the judgment result of the second sampling group is 1; determine that the judgment result of the current data bit is 1; if the first sampling result is 1, and the second sampling result is 0; then determine that the judgment result of the current data bit is 0; after completing the sampling of the data bit, if the data frame has not been sampled, return to step S22; if the data frame has been sampled, return to step S02.

[0006] Furthermore, the default value of the Tp interval is 50us.

[0007] Furthermore, the first storage space is a storage space located in a decoder.

[0008] Furthermore, the first storage space is a register space located in a decoder.

[0009] Furthermore, after obtaining the Tp interval, a warning range is defined according to the Tp interval value of the current data frame. If the rising / falling edge of the pulse in the data stream appears within the warning range, the warning flag is set, and the user is reminded of early warning based on the warning flag.

[0010] Furthermore, the decoder is connected to a vehicle-mounted microcontroller.

[0011] A wheel speed adaptive decoding system based on AK protocol, wherein the wheel speed adaptive decoding system based on AK protocol is used to implement the above-mentioned wheel speed adaptive decoding method based on AK protocol.

[0012] An AK protocol-based adaptive wheel speed decoding control digital logic, the AK protocol-based adaptive wheel speed decoding control digital logic is used to implement the above-mentioned AK protocol-based adaptive wheel speed decoding method.

[0013] A wheel speed adaptive decoding control chip based on AK protocol, wherein the wheel speed adaptive decoding control chip based on AK protocol is used to implement the above-mentioned wheel speed adaptive decoding method based on AK protocol.

[0014] An AK protocol-based adaptive wheel speed decoding control circuit, characterized in that the AK protocol-based adaptive wheel speed decoding control circuit is used to implement the above-mentioned AK protocol-based adaptive wheel speed decoding method.

[0015] The beneficial effects of the present invention include: (1) By estimating the sampling point of each bit of data in the adaptively calculated data frame through dynamic Tp interval, the sampling point can be dynamically adjusted during actual use to ensure the reliability of sampling, and then the sampling and decoding reliability can be improved through the Tp interval obtained by adaptive calculation; further, the next Manchester data sampling point is adjusted through dynamic balance, and the warning range is set to detect the current sensor unreliable warning as a safety reference, which can be used for chassis safety protection; This method is particularly suitable for single-line mode, which can not only ensure the accurate acquisition of speed information, but also save IO resources on the chip; (2) It has strong adaptability to different working conditions. Based on the detection environment and its working conditions, the estimation of the Tp interval can dynamically adapt to the vehicle speed detection process, thereby saving software and hardware resources when the vehicle is stable. In the case of poor environment, the sampling method is adjusted in advance and the Tp interval is determined, which saves on-chip resources to the greatest extent while ensuring the reliability of speed detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application, but do not constitute an improper limitation of the present invention. In the drawings: Figure 1 This is a schematic diagram of the AK protocol encoding method in wheel speed detection provided by the present invention.

[0017] Figure 2 This is a schematic diagram of the AK protocol-based adaptive wheel speed decoding method provided by the present invention.

[0018] Figure 3 A schematic diagram of the data decoding process and oversampling thereof provided by the present invention.

[0019] Figure 4 A schematic diagram of setting a warning range based on the Tp interval provided by the present invention. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, wherein the illustrative embodiments and descriptions are only used to explain the present invention but are not intended to limit the present invention.

[0021] The present invention proposes an adaptive wheel speed decoding method and system based on the AK protocol; the main principle of the AK protocol is to reflect speed information through the induction magnetic field generated by the Hall sensor and the rotation of the gear. Similarly, rotations in different directions can also be obtained by the gear passing through the Hall sensor. At this time, a sine curve as shown in Figure 1 is obtained, where the intersection position with the horizontal line is the speed zero crossing. Therefore, the speed zero crossing can be considered as a speed pulse; after analog rectification, amplification, filtering and other operations, it is reflected as Figure 1 the digital signal below; in order to increase the anti-interference of the data and the stability of the data stream, the Manchester coding method is correspondingly adopted, that is, there needs to be a corresponding edge change between one complete piece of data; and the three-current method is adopted, and the pulse interval is Tp; Preferably: in the three-current method adopted, the current Icch of the speed pulse is 28 mA, the current Iccm of the data pulse is 14 mA, and the static current IccL is 7 mA; Preferably: the default value of the pulse interval Tp is 50 us, and the range of change specified by the protocol is 40 us < Tp < 60 us; that is to say, under actual working conditions, the pulse interval Tp is dynamically changed and allowed; this will lead to data errors; As shown in the appendix Figure 1 When the AK protocol is used for wheel speed detection, 9 bits of data are defined, where: the bit of Icch in the figure (also called the 0th bit) is the speed pulse bit, and the subsequent bits are data bits, where: the first bit (the position of 0 in the figure) represents the air gap size, the second bit (the position of 1 in the figure) represents the amplitude validity, the third bit (the position of 2 in the figure) is user-defined, the fourth bit (the position of 3 in the figure) represents the direction validity, the fifth bit (the position of 4 in the figure) represents the direction, the sixth to eighth bits (5-7 in the figure) represent the amplitude size, and the ninth bit (the position of 8 in the figure) represents the parity check bit; the speed pulse bit can be transmitted on a separate speed pulse line. At this time, the first bit on the data line is the first bit; As shown in the appendix Figure 2 The adaptive wheel speed decoding method based on the AK protocol specifically includes the following steps: Step S01: After the decoder is powered on, judge the current detection mode; specifically: Step S011: Judge whether the current detection mode is a single-line mode or a double-line mode; if it is a single-line mode, go to step S012, otherwise, go to step S013; Preferably: the default value of the detection mode is the single-line mode; Step S012: when configured as single-line mode, determine whether there is data flow, if so, wait for the current data flow to be completed and meet the idle condition, and wait for the first pulse in the subsequent first data flow as the speed pulse; otherwise, there is no data flow, wait for the data flow of the data line to occur, and take the first pulse in the subsequent data flow as the speed pulse; enter step S02; Preferably: the idle condition is that the data line idle time is greater than or equal to an idle threshold; Step S013: when configured in dual-line mode, waiting for the first pulse on the speed pulse line to be used as the speed pulse; Step S02: when the first pulse arrives, record the current timestamp (that is, the timestamp of the rising edge) and the timestamp of the falling edge to calculate the width of the speed pulse, and use the width as the estimated Tp interval; write the estimated Tp interval into the first storage space; Preferably: the step S02 is performed in parallel using independent logic and sampling process (steps S1-S3), the arrival of the first pulse in the next data frame is discovered by independent logic, and the estimated Tp interval used in the next data frame is determined based on the speed pulse; the logic includes software logic and hardware logic; in this way, the Tp interval determination step S02 and the Tp interval acquisition step S1 can be performed in parallel; of course, it can also be set to a non-independent manner, so that serial work is required; The step S01 or S02 further includes determining an estimation accuracy mode after the decoder is powered on; the estimation accuracy mode includes a high-precision mode, a medium-precision mode and / or a low-precision mode; wherein: in the high-precision mode, the Tp interval is estimated for each pulse or a specific pulse position; in the medium-precision mode, the Tp interval is estimated once for each data frame; in the low-precision mode, the Tp interval is estimated once for N data frames; Preferably: the first storage space is a storage space located in a decoder; Preferably: the first storage space is a register space located in a decoder; Preferably: the first storage space is a storage space located in the AK protocol-based adaptive wheel speed decoding system; Preferably: after the decoder is powered on, the default value of the Tp interval is read from the non-volatile storage space and written into the first storage space; in the non-estimation mode, the first storage space maintains the default value of the written Tp interval; that is, 50us, and the value in the first storage space is unchanged subsequently; in the estimation accuracy mode (including the high-precision mode, the medium-precision mode and / or the low-precision mode), in the subsequent decoding process, the Tp interval value needs to be adaptively re-determined and written into the first storage space; Step S1: Get the current Tp interval; specifically: read the value of the Tp interval from the first storage space; considering that in actual use, due to the influence of external factors such as working conditions, the Tp interval value cannot be ideally maintained at a certain value, and it is very likely to fluctuate continuously; therefore, it is extremely important to dynamically capture the Tp interval value to adjust the positions of the first, second and evaluation bits; whether it is a dual-line mode or a single-line mode, the speed pulse will be reflected on the data line, so the first pulse received on the data line can be considered as a speed pulse, and at this time, the current Tp interval can be obtained by estimating the width value of the speed pulse width, so as to perform subsequent adaptive calculations and sampling point analysis; the Tp interval adapted to each frame of data can be accurately determined, and the accuracy of sampling can be guaranteed; Further: determining the timing of entering step S02 or S1 based on the estimation accuracy mode; specifically: In high-precision mode, the Tp interval needs to be re-determined and obtained before sampling each pulse or specific pulse, that is, entering step 02; in this mode, the Tp interval required for sampling the next pulse (specific pulse) is estimated by determining the width of the previous pulse; for the same data frame (the same decoding process), the same oversampling ratio can be used during sampling; that is, in high-precision mode, there is no need to change the oversampling ratio, and the determination of the oversampling ratio only occurs when the first Tp interval in the data frame is determined; in view of the occurrence of transmission anomalies between specific pulse bits during the transmission process, the high-precision mode can be selected to estimate the Tp interval value before the specific pulse is transmitted to overcome the possible missampling caused by the anomaly; this high-precision mode is used under specific working conditions and is generally set before the decoder is powered on; In the medium-precision mode, after the first speed pulse of a new data frame, that is, after a data frame is transmitted, the Tp interval is re-determined; compared with the high-precision mode and the low-precision mode, the medium-precision mode is a compromise solution; when the decoder is not powered on for the first time, before sampling each data frame, step S02 and step S1 are entered to determine and obtain the current Tp interval; while in the low-precision mode, the Tp interval is estimated every N data frames; where: N is a dynamic or static value; Preferably: the default value of the estimation accuracy mode is the medium accuracy mode; and the medium accuracy mode and the low accuracy mode can be converted to each other; In the low-precision mode, the Tp interval is estimated once every N data frames, that is, after every N data frames are transmitted, the step S02 is entered to re-determine the Tp interval; an N-value counter is required to determine whether N data frames have been reached; The medium-precision mode and the low-precision mode can be converted to each other, specifically: Step S1A1: monitor the current detection environment in real time to determine whether the detection environment has changed; if so, proceed to the next step; otherwise, maintain the current N value and / or maintain the current estimation accuracy mode; that is, determine whether the decoding working conditions have changed by detecting the environment; so that when the working conditions are stable, the estimation overhead can be reduced, thereby improving the decoding efficiency; Preferably: the N is 2 or more; the initial value of N is set to 2; The current detection environment is monitored through environmental parameters; environmental parameters include: one or more of weather, road conditions, tire conditions, vehicle load, electronic interference, sensor installation conditions, driving vibration, sensor pollution or corrosion, etc.; weather includes temperature, humidity, weather conditions (rain, snow, ice), etc.; road conditions include: flatness, slippery, bumpy, etc.; tire conditions include tire pressure, wear, grip, etc.; Preferably: based on the changes in the detection environment that will occur, the current N value and / or estimation accuracy mode is changed in advance; for example: for electronic interference, when electromagnetic interference (such as other electrical equipment, high-voltage cables) may occur in the area where the vehicle enters, thereby interfering with the sensor signal acquisition, the N value can be appropriately adjusted to a smaller value in advance before entering the area; (when the N value is already very small, for example, equal to 2, the estimation accuracy mode can be directly changed) or the estimation accuracy mode is changed, the low-precision mode is changed to the medium-precision mode, and the state of data frame-by-data frame detection is entered in advance; Step S1A2: dynamically adjust the N value according to the direction of the change in the detection environment, so that when the detection environment becomes better, the N value is increased (currently in low-precision mode) or the medium-precision mode is changed to the low-precision mode (currently in medium-precision mode); conversely, when the detection environment becomes worse, the N value is reduced until the medium-precision mode is entered when N=1; that is, when the detection environment is good, a larger N value can be maintained, and even the longer the good detection environment is maintained, the larger the N value; conversely, when the detection environment is bad, the N value can be adjusted at a certain frequency, and even the longer the bad detection environment is maintained, the smaller the N value is, and even when the N value has reached 2, the medium-precision mode is directly entered; Further: dynamically adjusting the N value based on the degree of change in the detection environment, so that the greater the degree of change, the greater the degree of adjustment of the N value; conversely, the smaller the degree of change, the smaller the degree of adjustment of the N value; In the low-precision estimation mode, the Tp interval needs to be re-determined and obtained once each time the transmission of N data frames is completed; if the N value changes or the precision estimation mode changes, it is necessary to enter step S02 to re-determine the Tp interval and write it into the first storage space, so that after the detection of the current data frame is completed, the Tp interval is re-read from the first storage space in step S1, so that the re-determined Tp interval is used in the sampling and decoding process of the next data frame; and a new precision estimation mode or N value is enabled; Preferably: the above conversion control operation is completed by software logic located in the operating system, or hardware logic located in the decoder or the vehicle controller; Step S2: Calculate sampling points based on the Tp interval; perform multiple continuous sampling based on the calculated oversampling points; determine the decision result of the sampling group based on the sampling result, and determine the current data bit value based on the decision result; specifically includes the following steps: Step S21: setting a correspondence table between Tp interval and oversampling ratio, and obtaining the oversampling ratio corresponding to the current Tp interval by querying the correspondence table; for example, when the Tp interval is 50us, a 32-fold oversampling method is adopted; Preferably: the correspondence table between the Tp interval and the oversampling ratio is preset; the setting method is to make the oversampling ratio M and the Tp interval satisfy the following conditions 1-3; Condition 1: ; Condition 2: ; Condition 3: ; Preferably: after obtaining the Tp interval, a warning range is defined according to the Tp interval value of the current data frame. If the rising / falling edge of the pulse in the data stream appears within the warning range, a warning flag is set, and based on the warning flag, a user is reminded of early warning, thereby improving the security and reliability of decoding; further, a detection program is provided in the operating system to perform real-time detection on the value of the warning flag. When the flag is set, the user is reminded of early warning through multimedia; Preferably: the multimedia method includes audio, video, etc.; Alternatively: after setting the warning flag, the decoder pushes a warning message to the operating system through a push pipeline; The warning range is defined according to the Tp interval value of the current data frame, specifically: the estimated occurrence time of each subsequent pulse is obtained according to the Tp interval value of the current data frame and the rising edge timestamp of the speed pulse. If the rising edge of each pulse appears outside the warning range, it is considered that the Manchester decoding requirement is met. If it appears within the warning range, it is considered that there may be a problem with the Manchester decoding at this time, and the warning flag is set; Preferably, the warning range is set to the range around the time when the rising edge and falling edge of each pulse should occur calculated based on the estimated Tp interval and the first pulse occurrence timestamp (the rising edge timestamp of the first pulse); Figure 4 As shown, the shaded part in the figure is the warning range of the third position; Alternatively: the definition of the warning line range is specifically as follows: based on the estimated Tp interval value, the time of occurrence of each pulse P is calculated, and at the same time, the low level / high level in the Manchester coding bit is counted (i.e., the high and low levels within a Tp width); if the corresponding edge occurs, the count value is less than the bit number value of the pulse P corresponding to the timestamp, then the warning flag is set, otherwise it is considered that the coding meets the requirements; in this way, the edge occurrence timing is detected in each Manchester coding cycle, which improves the ability to detect erroneous coding. Users can set the corresponding warning line, predict the stability of data on the data transmission line in advance, and then identify whether the sensor is in a normal state; the bit number P of the pulse P is numbered in sequence of 1, 2, ...; Step S22: Initialize the sampling count value in the data frame to 0 at the rising edge of the first pulse; perform continuous sampling at a sampling rate of M, and increment the sampling count value each time a sampling is completed; if it is determined that three consecutive sampling values ​​are 0, then continue sampling; set the sampling count value to The sampling result at 1000 is taken as the second sampling group. The sampling result at that time is taken as the first sampling group; the first sampling group and the second sampling group are judged within the sampling group using the best-of-three system. When two of the three sampling results in the sampling group are greater than or equal to 1, the judgment result of the sampling group is 1; otherwise, the judgment result is 0; the sampling count value is cleared when it reaches the sampling multiple; Preferably: when the sampling count value reaches the idle threshold, the count value is maintained, and continuous sampling is performed until an edge arrives, then the counter is cleared and the count is restarted; when the sampling count value reaches 31 (less than the sampling multiplier value), if a non-zero sampling result or non-zero judgment result has been obtained before, the sampling count value is reset to 0 (otherwise it is in the idle counting process); Preferably, the idle threshold is a preset value, for example, equal to 41; Preferably: the idle threshold is a value related to the sampling rate; Step S3: Determine the current data bit value based on the judgment results of the first sampling group and the second sampling group; specifically: determine whether the judgment results of the first sampling group and the second sampling are equal; if they are equal, it is deemed that the Manchester encoding rule is not satisfied, and the sampled data is determined to be incorrect. If the judgment result of the first sampling group is 0 and the judgment result of the second sampling group is 1, the judgment result of the current data bit is determined to be 1; if the first sampling result is 1 and the second sampling result is 0, the judgment result of the current data bit is determined to be 0; after completing the sampling of the data bit, if the data frame has not been sampled, return to step S22; if the data frame has been sampled, return to step S02 or S22 (or step S1); Preferably: if the data frame has been sampled, if the current estimation accuracy mode is the medium accuracy mode, then return to step S02; if the current estimation accuracy mode is the low accuracy mode, increment the N value counter to further determine whether the N value counter reaches the N value in the current low accuracy mode, if not, return to step S1 or S22 (or step S1) (at this time, the Tp interval continues to be used), otherwise, return to step 02; when entering the low accuracy mode for the first time, initialize the N value counter to 0; Preferably: this step is performed at the evaluation position, and the evaluation value is a preset value, for example: Department; Embodiment 1, as Figure 3 As shown, in the present invention, the data bits defined by the AK protocol are oversampled, and a best-of-three judgment is performed at the specified sampling point to ensure the accuracy of the data; the figure shows a sampling schematic diagram of a Tp interval of 50us, and the event interval in each dotted box is 50us. At this time, when the 32-fold oversampling method is fixed, the sampling counter runs freely. If there is no data edge, the sampling counter is kept when it reaches 41; at this time, if an edge arrives, the counter is cleared and counted up again, and sampling is performed when the counter reaches 1 / 4Tp, that is, the second sampling in the figure is performed when the counter is 8; due to the best-of-three system, it is necessary to judge whether there are two at positions 7, 8, and 9. and above are 1 to obtain 1, at which time the sampling obtains the corresponding value; the first sampling position is at 3 / 4Tp, at which time the counter corresponding value is 24; similarly, the values ​​of the three positions 23, 24, and 25 need to be judged to obtain the corresponding sampling value; the evaluation bit is judged at 1 / 2Tp; during the evaluation, it is judged whether the values ​​of the first and second samples are equal; if they are equal, the Manchester encoding rule is not met, and the data is considered to be incorrect. If the first sampling result is 0 and the second sampling result is 1; then the final result of the current data is judged to be 1; if the first sampling result is 1 and the second sampling result is 0; then the final result of the current data is judged to be 0; Based on the same inventive concept, the present invention proposes an AK protocol-based adaptive wheel speed decoding system, the system is used to implement the above-mentioned AK protocol-based adaptive wheel speed decoding method; Based on the same inventive concept, the present invention proposes an adaptive wheel speed decoder based on the AK protocol, and the decoder is used to implement the adaptive wheel speed decoding method based on the AK protocol; A computer program (also referred to as a program, software, software application, script, or code) can be written in any form of a programming language, including an assembled or interpreted language, a declarative or procedural language, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program, or in multiple collaborative files (e.g., files storing one or more modules, subroutines, or code portions). A computer program can be deployed to execute on one computer or on multiple computers located at one site or distributed across multiple sites and interconnected by a communication network.

[0022] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0023] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0024] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0025] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A wheel speed decoding method based on AK protocol, characterized in that: The method comprises: Step S02: when the first pulse arrives, record the current timestamp and the timestamp of the falling edge to calculate the width of the speed pulse, and write the width into the first storage space as the estimated Tp interval; Step S1: Reading Tp interval from the first storage space; Step S2: Calculate sampling points based on the Tp interval; oversample the data frame based on the sampling points and determine the value of each data bit; specifically includes the following steps: Step S21: setting a correspondence table between Tp intervals and sampling points, and obtaining an oversampling point corresponding to the current Tp interval by querying the correspondence table; Step S22: Continuously sample at the sampling rate and use the sampling count value to count; equal the sampling count value to The sampling result at 1000 is taken as the second sampling group. The sampling result at that time is taken as the first sampling group; the first sampling group and the second sampling group are judged within the group using the best-of-three system. When two of the three sampling results in the sampling group are greater than or equal to 1, the judgment result of the sampling group is 1; otherwise, the judgment result is 0; Step S3: Determine the current data bit value based on the judgment results of the first sampling group and the second sampling group; determine whether the judgment results of the first sampling group and the second sampling are equal; if they are equal, determine that the sampled data is incorrect, if the judgment result of the first sampling group is 0, and the judgment result of the second sampling group is 1; determine that the judgment result of the current data bit is 1; if the first sampling result is 1, and the second sampling result is 0; then determine that the judgment result of the current data bit is 0; After the data bits are sampled, if the data frame has not been sampled, the process returns to step S22; If the data frame has been sampled, the process returns to step S02.

2. The method for adaptive wheel speed decoding based on AK protocol according to claim 1, characterized in that: The default value of Tp interval is 50us.

3. The method for adaptive wheel speed decoding based on AK protocol according to claim 2, characterized in that: The first storage space is a storage space located in the decoder.

4. The method for adaptive wheel speed decoding based on AK protocol according to claim 3, characterized in that: The first storage space is a register space located in a decoder.

5. The method for adaptive wheel speed decoding based on AK protocol according to claim 4, characterized in that: After obtaining the Tp interval, the warning range is defined according to the Tp interval value of the current data frame. If the rising / falling edge of the pulse in the data stream appears within the warning range, the warning flag is set, and the user is reminded of early warning based on the warning flag.

6. The method for adaptive wheel speed decoding based on AK protocol according to claim 5, characterized in that: The decoder is connected to a vehicle-mounted microcontroller.

7. An adaptive wheel speed decoding system based on AK protocol, characterized in that: The AK protocol-based adaptive wheel speed decoding system is used to implement the AK protocol-based adaptive wheel speed decoding method described in any one of claims 1 to 6.

8. An adaptive wheel speed decoding control chip based on AK protocol, characterized in that: The AK protocol-based adaptive wheel speed decoding control chip is used to implement the AK protocol-based adaptive wheel speed decoding method described in any one of claims 1 to 6.

9. An adaptive wheel speed decoding control circuit based on AK protocol, characterized in that: The AK protocol-based adaptive wheel speed decoding module is used to implement the AK protocol-based adaptive wheel speed decoding method described in any one of claims 1 to 6.

Images