A method and device for measuring automobile steering transmission ratio based on ESC self-learning calibration

Abstract

The present invention provides a method and device for measuring the steering gear ratio of an automobile based on ESC self-learning calibration, belonging to the field of vehicle engineering technology. The method comprises: S1, after the vehicle to be tested drives to a test site, a host computer sends a self-learning instruction to the electronic stability system (ESC), and then enters S2; S2, determines whether the steering angle and inertial measurement unit (IMU) have been verified; if the verification is complete, enters S3; otherwise, the steering angle and IMU are verified; S3, determines whether the vehicle to be tested has an active steering function; if so, measures the vehicle's steering gear ratio based on the active steering function of the vehicle to be tested; otherwise, enters S4; S4, measures the vehicle's steering gear ratio by manually operating the steering wheel. The solution of the present invention has a small measurement error, is quick and convenient to implement, and can measure and process both left and right steering ratios.

Description

Technical Field

[0001] The present invention relates to the field of vehicle engineering technology, and in particular to a method and device for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration. Background Art

[0002] Currently, people are demanding higher standards for automotive braking safety and comfort, leading to an increasing number of vehicles being equipped with electronic braking systems. These systems, such as the Electronic Stability Program (ESC), brake-by-wire systems (Brake-by-Wire), and automated parking systems, all require a steering ratio. The steering ratio, also known as the steering system angular ratio, is the ratio of the steering wheel angle to the steering wheel deflection angle on the same side of the steering wheel, generally denoted by iw. This ratio is the product of the steering gear angular ratio (i1) and the steering mechanism angular ratio (i2). If a full rotation of the steering wheel (360 degrees) results in a 20-degree wheel turn, the steering ratio is 360 divided by 20, or 18:1. The steering ratio parameter directly impacts the control performance of the ESC or Onebox. Improper steering ratio settings can cause the vehicle to understeer or oversteer, potentially leading to loss of control and potentially damaging life and property. In addition, the steering transmission ratio parameter is directly involved in the calculation of the electronic stability control system and will directly affect the calculation of the Ackerman angle. The Ackerman angle affects the calculation of the target yaw rate, thereby affecting the calculation of the vehicle handling stability braking force or the calculation of the automatic parking steering angle.

[0003] The ESC learning process for steering ratio characteristics is required for all new vehicle models with the following new features: Steering performance changes due to front or rear axle steering or suspension performance: new front axle steering gear, steering linkage changes, left-hand or right-hand drive steering, changes in the axle configuration of the additional steering axle, and rear (additional) axle self-steering. If there is any doubt about whether the new model will affect steering performance, a steering ratio learning process is recommended. After learning the steering ratio, the parameters are written to the vehicle's electronic control unit (ECU). This optimizes control parameters, improves vehicle stability during ESC control, and enhances vehicle comfort, safety, and automatic parking accuracy.

[0004] Currently, literature has disclosed a method for automatically calibrating the steering wheel transmission ratio and another method for automatically calibrating the steering wheel transmission ratio. However, both methods require manual drawing of straight lines and curves on the ground and then manually measuring the distances. This process is subject to significant errors and can only measure the rotation ratio in one direction, while in reality, the left and right rotation ratios are different. Therefore, existing automotive steering transmission ratio measurement methods suffer from large errors and single-valued measurement results, failing to meet practical needs. Summary of the Invention

[0005] The embodiment of the present invention provides a method and device for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration, so as to solve the technical problems that the existing automobile steering transmission ratio measurement scheme has large errors, single measurement results and cannot meet actual needs.

[0006] To solve the above technical problems, the embodiments of the present invention provide the following technical solutions:

[0007] In one aspect, an embodiment of the present invention provides a method for measuring a steering gear ratio of an automobile based on ESC self-learning calibration. The method for measuring a steering gear ratio of an automobile based on ESC self-learning calibration includes:

[0008] S1: After the vehicle to be tested arrives at the test site, the host computer sends a self-learning instruction to the ESC (Electronic Stability Program), and then enters S2;

[0009] S2, determine whether the steering angle and the inertial measurement unit (IMU) are calibrated. If the steering angle and the inertial measurement unit are calibrated, proceed to S3; otherwise, calibrate the steering angle and the inertial measurement unit.

[0010] S3, determining whether the vehicle to be tested has an active steering function. If the vehicle to be tested has an active steering function, measuring the steering gear ratio of the vehicle based on the active steering function of the vehicle to be tested; otherwise, proceeding to S4;

[0011] S4 measures the vehicle's steering gear ratio based on the way the steering wheel is manually operated.

[0012] Optionally, the calibrating the steering angle and the inertial measurement unit includes:

[0013] S21, controlling the vehicle to travel a preset distance in a straight line at a preset speed, maintaining the speed for a first preset time within an allowable error of the preset speed, and sending a heading angle zero point calibration command from the host computer to perform a heading angle zero point calibration. After the calibration is completed, the ESC collects multiple sets of heading angle values ​​within a second preset time;

[0014] S22: If the average of the multiple sets of azimuth angle values ​​collected is within the first preset error interval, it is determined that the azimuth angle zero point calibration is successful. At this time, multiple sets of yaw angular velocities and lateral accelerations are collected and recorded, and the recorded yaw angular velocities and lateral accelerations are low-pass filtered. If the average of the multiple sets of yaw angular velocities after filtering is not within the second preset error interval or the average of the multiple sets of lateral accelerations after filtering is not within the third preset error interval, an IMU installation failure is reported. If the average of the multiple sets of yaw angular velocities after filtering is within the second preset error interval and the average of the multiple sets of lateral accelerations after filtering is within the third preset error interval, the average of the multiple sets of yaw angular velocities after filtering at this time is used as the yaw angular velocity compensation value, and the average of the multiple sets of lateral accelerations after filtering is used as the lateral acceleration compensation value, and then the process proceeds to S3.

[0015] S23, if the average of the multiple sets of direction angle values ​​collected is not within the first preset error range, it is determined that the direction angle zero point check has failed, and the process returns to S21;

[0016] S24: If the azimuth zero point calibration fails three times in a row, a fault is reported. If you want to continue the azimuth zero point calibration, you need to power on the control system again and then return to S21.

[0017] Optionally, the calibrating the steering angle and the inertial measurement unit further includes:

[0018] After the heading angle zero point calibration is completed, control the vehicle speed within the first preset vehicle speed range, turn the steering wheel to the left at a speed greater than the first preset rotation speed, and record whether the positive and negative values ​​of the longitudinal acceleration, lateral acceleration, heading angle and yaw angular velocity meet the measurement coordinate system to verify the effect of the heading angle zero point calibration.

[0019] Optionally, measuring the steering gear ratio of the vehicle based on the active steering function of the vehicle to be tested includes:

[0020] S31, controlling the vehicle speed within a second preset vehicle speed range, controlling the steering wheel to turn left 90° at a speed greater than a second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period;

[0021] S32, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC;

[0022] S33, calculate the turning radius R using the following formula L :

[0023] R L =RL y

[0024]

[0025] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0026] S34, calculate the steering transmission ratio I using the following formula:

[0027]

[0028]

[0029] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0030] S35, repeating S33 to S34, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios;

[0031] S36, controlling the vehicle speed within the second preset vehicle speed range, turning the steering wheel another 90° to the left at a speed greater than the second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period; then repeating S32 to S35 until the steering wheel has been turned leftwards 360°, obtaining an average value of the four sets of steering gear ratios; averaging the average values ​​of the four sets of steering gear ratios to obtain a left-hand steering gear ratio;

[0032] S37, controlling the vehicle speed to be within the second preset vehicle speed range, controlling the steering wheel to turn right 90° at a speed greater than the second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period;

[0033] S38, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC;

[0034] S39, calculate the turning radius R using the following formula L :

[0035] R L =RL y

[0036]

[0037] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0038] S310: Calculate the steering transmission ratio I using the following formula:

[0039]

[0040]

[0041] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0042] S311, repeating S39 to S310, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios;

[0043] S312, control the vehicle speed within the second preset vehicle speed range, turn the steering wheel to the right again 90° at a speed greater than the second preset rotation speed, and keep the steering wheel angle unchanged for a third preset time; then repeat S38 to S311; until the angle of the steering wheel turned to the right reaches 360°, obtain the average value of the four groups of steering transmission ratios; take the average value of the four groups of steering transmission ratios to obtain the right steering transmission ratio.

[0044] Optionally, the steering ratio of the vehicle is measured by manually operating the steering wheel, including:

[0045] S41, controlling the vehicle speed within a third preset speed range and within a preset rotation error, manually operating the steering wheel to turn the steering wheel 90° to the left, and maintaining the steering wheel angle unchanged for a fourth preset time period;

[0046] S42, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC;

[0047] S43, calculate the turning radius R using the following formula L :

[0048] R L =RL y

[0049]

[0050] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0051] S44, calculate the steering transmission ratio I using the following formula:

[0052]

[0053]

[0054] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0055] S45, repeating S43 to S44, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple sets of steering gear ratios;

[0056] S46: Control the vehicle speed within the third preset speed range, manually operate the steering wheel, turn the steering wheel 90 degrees to the left again, and maintain the steering wheel angle unchanged for a fourth preset time period; then repeat S42 to S45 until the steering wheel is turned 360 degrees to the left, and obtain an average value of the four sets of steering gear ratios; average the average values ​​of the four sets of steering gear ratios to obtain the left steering gear ratio;

[0057] S47, controlling the vehicle speed within a third preset speed range, manually operating the steering wheel to turn the steering wheel 90° to the right, and maintaining the steering wheel angle unchanged for a fourth preset time period;

[0058] S48, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC;

[0059] S49, calculate the turning radius R using the following formula L :

[0060] R L =RL y

[0061]

[0062] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0063] S410: Calculate the steering transmission ratio I using the following formula:

[0064]

[0065]

[0066] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0067] S411, repeating S49 to S410, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios;

[0068] S412, control the vehicle speed within the third preset speed range, use manual steering wheel operation to turn the steering wheel to the right again 90°, and keep the steering wheel angle unchanged for a fourth preset time; then repeat S48 to S411; until the steering wheel is turned to the right at an angle of 360°, obtain the average value of the four groups of steering transmission ratios; take the average value of the four groups of steering transmission ratios to obtain the right steering transmission ratio.

[0069] On the other hand, the present invention also provides a device for measuring the steering gear ratio of an automobile based on ESC self-learning calibration, which includes: a self-learning instruction sending module, a verification module, a first steering gear ratio measuring module and a second steering gear ratio measuring module;

[0070] The self-learning instruction sending module is used to send a self-learning instruction to the ESC through the host computer after the vehicle to be tested drives to the test site, and trigger the verification module;

[0071] The verification module is used to determine whether the steering angle and the inertial measurement unit (IMU) are verified; if the steering angle and the inertial measurement unit are verified, the first steering transmission ratio measurement module is triggered; otherwise, the steering angle and the inertial measurement unit are verified;

[0072] The first steering transmission ratio measurement module is used to determine whether the vehicle under test has an active steering function. If the vehicle under test has an active steering function, the steering transmission ratio of the vehicle is measured based on the active steering function of the vehicle under test; otherwise, the second steering transmission ratio measurement module is triggered;

[0073] The second steering transmission ratio measurement module is used to measure the steering transmission ratio of the vehicle based on manual operation of the steering wheel.

[0074] Optionally, the step of the verification module verifying the steering angle and the inertial measurement unit includes:

[0075] S21, controlling the vehicle to travel a preset distance in a straight line at a preset speed, maintaining the speed for a first preset time within an allowable error of the preset speed, and sending a heading angle zero point calibration command from the host computer to perform a heading angle zero point calibration. After the calibration is completed, the ESC collects multiple sets of heading angle values ​​within a second preset time;

[0076] S22: If the average of the multiple sets of azimuth angle values ​​collected is within the first preset error interval, it is determined that the azimuth angle zero point calibration is successful. At this time, multiple sets of yaw angular velocities and lateral accelerations are collected and recorded, and the recorded yaw angular velocities and lateral accelerations are low-pass filtered. If the average of the multiple sets of yaw angular velocities after filtering is not within the second preset error interval or the average of the multiple sets of lateral accelerations after filtering is not within the third preset error interval, an IMU installation failure is reported. If the average of the multiple sets of yaw angular velocities after filtering is within the second preset error interval and the average of the multiple sets of lateral accelerations after filtering is within the third preset error interval, the average of the multiple sets of yaw angular velocities after filtering at this time is used as the yaw angular velocity compensation value, and the average of the multiple sets of lateral accelerations after filtering is used as the lateral acceleration compensation value, and then the process proceeds to S3.

[0077] S23, if the average of the multiple sets of direction angle values ​​collected is not within the first preset error range, it is determined that the direction angle zero point check has failed, and the process returns to S21;

[0078] S24: If the azimuth zero point calibration fails three times in a row, a fault is reported. If you want to continue the azimuth zero point calibration, you need to power on the control system again and then return to S21.

[0079] Optionally, the verification module is further configured to:

[0080] After the heading angle zero point calibration is completed, control the vehicle speed within the first preset vehicle speed range, turn the steering wheel to the left at a speed greater than the first preset rotation speed, and record whether the positive and negative values ​​of the longitudinal acceleration, lateral acceleration, heading angle and yaw angular velocity meet the measurement coordinate system to verify the effect of the heading angle zero point calibration.

[0081] Optionally, the step of measuring the steering transmission ratio of the vehicle by the first steering transmission ratio measurement module based on the active steering function of the vehicle to be tested includes:

[0082] S31, controlling the vehicle speed within a second preset vehicle speed range, controlling the steering wheel to turn left 90° at a speed greater than a second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period;

[0083] S32, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC;

[0084] S33, calculate the turning radius R using the following formula L :

[0085] R L =RL y

[0086]

[0087] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0088] S34, calculate the steering transmission ratio I using the following formula:

[0089]

[0090]

[0091] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0092] S35, repeating S33 to S34, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios;

[0093] S36, controlling the vehicle speed within the second preset vehicle speed range, turning the steering wheel another 90° to the left at a speed greater than the second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period; then repeating S32 to S35 until the steering wheel has been turned leftwards 360°, obtaining an average value of the four sets of steering gear ratios; averaging the average values ​​of the four sets of steering gear ratios to obtain a left-hand steering gear ratio;

[0094] S37, controlling the vehicle speed to be within the second preset vehicle speed range, controlling the steering wheel to turn right 90° at a speed greater than the second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period;

[0095] S38, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC;

[0096] S39, calculate the turning radius R using the following formula L :

[0097] R L =RL y

[0098]

[0099] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0100] S310: Calculate the steering transmission ratio I using the following formula:

[0101]

[0102]

[0103] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0104] S311, repeating S39 to S310, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios;

[0105] S312, control the vehicle speed within the second preset vehicle speed range, turn the steering wheel to the right again 90° at a speed greater than the second preset rotation speed, and keep the steering wheel angle unchanged for a third preset time; then repeat S38 to S311; until the angle of the steering wheel turned to the right reaches 360°, obtain the average value of the four groups of steering transmission ratios; take the average value of the four groups of steering transmission ratios to obtain the right steering transmission ratio.

[0106] Optionally, the second steering transmission ratio measurement module is specifically configured to perform the following steps:

[0107] S41, controlling the vehicle speed within a third preset speed range and within a preset rotation error, manually operating the steering wheel to turn the steering wheel 90° to the left, and maintaining the steering wheel angle unchanged for a fourth preset time period;

[0108] S42, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC;

[0109] S43, calculate the turning radius R using the following formula L :

[0110] R L =RL y

[0111]

[0112] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0113] S44, calculate the steering transmission ratio I using the following formula:

[0114]

[0115]

[0116] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0117] S45, repeating S43 to S44, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple sets of steering gear ratios;

[0118] S46: Control the vehicle speed within the third preset speed range, manually operate the steering wheel, turn the steering wheel 90 degrees to the left again, and maintain the steering wheel angle unchanged for a fourth preset time period; then repeat S42 to S45 until the steering wheel is turned 360 degrees to the left, and obtain an average value of the four sets of steering gear ratios; average the average values ​​of the four sets of steering gear ratios to obtain the left steering gear ratio;

[0119] S47, controlling the vehicle speed within a third preset speed range, manually operating the steering wheel to turn the steering wheel 90° to the right, and maintaining the steering wheel angle unchanged for a fourth preset time period;

[0120] S48, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC;

[0121] S49, calculate the turning radius R using the following formula L :

[0122] R L =RL y

[0123]

[0124] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0125] S410: Calculate the steering transmission ratio I using the following formula:

[0126]

[0127]

[0128] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0129] S411, repeating S49 to S410, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios;

[0130] S412, control the vehicle speed within the third preset speed range, use manual steering wheel operation to turn the steering wheel to the right again 90°, and keep the steering wheel angle unchanged for a fourth preset time; then repeat S48 to S411; until the steering wheel is turned to the right at an angle of 360°, obtain the average value of the four groups of steering transmission ratios; take the average value of the four groups of steering transmission ratios to obtain the right steering transmission ratio.

[0131] On the other hand, the present invention further provides an electronic device, comprising a processor and a memory; the memory stores at least one instruction, and the instruction is loaded and executed by the processor to implement the above method.

[0132] In yet another aspect, the present invention further provides a computer-readable storage medium, wherein the storage medium stores at least one instruction, and the instruction is loaded and executed by a processor to implement the above method.

[0133] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0134] Compared to existing automotive steering ratio measurement methods, which require manual drawing of straight lines and curves on the ground and then manually measuring distances, resulting in large errors and measuring only the ratio in one direction, the present invention reduces measurement errors and directly uses sensors to acquire data, offering a quick and convenient method. Furthermore, the present invention can measure and process both left and right ratios. This solves the problem of steering performance changes caused by steering and suspension performance of the front or rear axle, resulting in understeer or oversteer control when ESC and Onebox control become unstable, and inaccurate automatic parking leading to incorrect parking positions. BRIEF DESCRIPTION OF THE DRAWINGS

[0135] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0136] Figure 1 1 is a schematic diagram of an execution flow of a method for measuring a vehicle steering ratio based on ESC self-learning calibration according to an embodiment of the present invention;

[0137] Figure 2 1 is a schematic diagram of a detailed execution flow of a method for measuring a vehicle steering transmission ratio based on ESC self-learning calibration according to an embodiment of the present invention;

[0138] Figure 3It is a schematic diagram of the vehicle steering driving model;

[0139] Figure 4 is a schematic diagram of a bicycle model of vehicle steering;

[0140] Figure 5 This is a system block diagram of a device for measuring a vehicle steering transmission ratio based on ESC self-learning calibration according to an embodiment of the present invention. DETAILED DESCRIPTION

[0141] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other in the absence of conflict.

[0142] Furthermore, it should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the associated drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products, or apparatus.

[0143] First embodiment

[0144] In view of the problems that the existing automobile steering transmission ratio measurement scheme has large errors and single measurement results, which cannot meet actual needs, this embodiment provides a method for measuring the automobile steering transmission ratio based on ESC self-learning calibration, which is applicable to ESC, Onebox wire control brake, automatic parking and other products in the field of automobile active braking safety for commercial vehicles and passenger cars; the method of this embodiment can be implemented by electronic equipment. Specifically, the execution process of the method is as follows Figure 1 As shown, it includes the following process steps:

[0145] S1, after the vehicle to be tested drives to the test site, the host computer sends a self-learning instruction to the ESC (Electronic Stability Program), and then enters S2;

[0146] Among them, the test site is generally a large flat square.

[0147] S2: Determine whether the steering angle sensor (SAS) and inertial measurement unit (IMU) have been verified. If the SAS and IMU are verified, proceed to S3. Otherwise, calibrate the SAS and IMU until they are complete. The specific verification process is as follows:

[0148] S21: Control the vehicle to travel 250 meters in a straight line at a speed of 20 km / h. When the speed is between 19 km / h and 21 km / h, maintain the speed for 3 seconds. The host computer sends a direction angle zero point calibration command to perform the direction angle zero point calibration. After the calibration is completed, the ESC system collects 10 sets of direction angle values ​​within 10 seconds.

[0149] S22: If the average of the 10 sets of azimuth angle values ​​collected is between -10° and +10°, it is determined that the azimuth angle zero point calibration is successful. At this time, 10 sets of yaw rate YawRate and lateral acceleration Ay are collected and recorded, and the recorded YawRate and Ay are low-pass filtered. If the average of the 10 sets of yaw rate after filtering is not between -1.5° and +1.5° or the average of the 10 sets of lateral acceleration after filtering is not -1m / s 2 Up to +1m / s 2 If the average of the 10 filtered yaw rates is between -1.5° and +1.5° and the average of the 10 filtered lateral accelerations is between -1m / s 2 Up to +1m / s 2 The average value of the 10 filtered yaw angular velocities at this time is used as the yaw angular velocity compensation value, and the average value of the 10 filtered lateral accelerations is used as the lateral acceleration compensation value, and then enters S3;

[0150] S23, if the average of the 10 sets of direction angle values ​​collected is not between -10° and +10°, it is determined that the direction angle zero point check has failed, and the process returns to S21;

[0151] S24: If the azimuth zero point calibration fails three times in a row, a fault is reported. If you want to continue the azimuth zero point calibration, you need to power on the control system again and then return to S21.

[0152] In addition, in this embodiment, the steering angle and inertial measurement unit are verified, which also includes: after the zero-point verification of the heading angle is completed, the vehicle speed is controlled from 0-20 km / h, the steering wheel is turned to the left at a speed greater than 350° / s, and the positive and negative values ​​of the longitudinal acceleration, lateral acceleration, heading angle and yaw angular velocity are recorded to see whether they meet the measurement coordinate system. If they do, it means that the zero-point verification of the heading angle is successful.

[0153] S3, determining whether the vehicle to be tested has an active steering function. If the vehicle to be tested has an active steering function, measuring the steering gear ratio of the vehicle based on the active steering function of the vehicle to be tested; otherwise, proceeding to S4;

[0154] Specifically, if Figure 2 As shown, the steering gear ratio of the vehicle is measured based on the active steering function of the vehicle under test, including:

[0155] S31: Control the vehicle speed between 20km / h and 25km / h, turn the steering wheel 90° to the left at a speed greater than 150° / s, and maintain the steering wheel angle for 4 seconds;

[0156] S32, collects 10 sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC system;

[0157] S33, calculate the turning radius R using the following formula L :

[0158] R L =RL y

[0159]

[0160] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0161] S34, calculate the steering transmission ratio I using the following formula:

[0162]

[0163]

[0164] Among them, Lw is the steering wheel angle; L is the vehicle wheelbase; the vehicle steering driving model is as follows Figure 3 As shown in , when the vehicle model is converted into a bicycle model, δ is the steering angle of the front wheel, as Figure 4 shown.

[0165] S35, repeating S33 to S34, calculating 10 sets of steering gear ratios using the collected 10 sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the 10 sets of steering gear ratios;

[0166] S36: Control the vehicle speed to be between 20 km / h and 25 km / h, turn the steering wheel 90 degrees to the left again at a speed greater than 150 degrees / s, and maintain the steering wheel angle for 4 seconds; then repeat S32 to S35; until the steering wheel is turned to the left at an angle of 360 degrees, obtain the average value of the four sets of steering gear ratios; average the average values ​​of the four sets of steering gear ratios to obtain the left steering gear ratio;

[0167] S37: Control the vehicle speed between 20km / h and 25km / h, turn the steering wheel 90° to the right at a speed greater than 150° / s, and maintain the steering wheel angle for 4 seconds;

[0168] S38, collects 10 sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC system;

[0169] S39, calculate the turning radius R using the following formula L :

[0170] R L =RL y

[0171]

[0172] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0173] S310: Calculate the steering transmission ratio I using the following formula:

[0174]

[0175]

[0176] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0177] S311, repeating S39 to S310, calculating 10 sets of steering gear ratios using the collected 10 sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average of the 10 sets of steering gear ratios;

[0178] S312: Control the vehicle speed to between 20 km / h and 25 km / h, turn the steering wheel to the right again by 90 degrees at a speed greater than 150 degrees / s, and maintain the steering wheel angle for 4 seconds; then repeat S38 to S311; until the steering wheel is turned to the right by an angle of 360 degrees, obtain the average value of the four sets of steering transmission ratios; take the average value of the four sets of steering transmission ratios to obtain the right steering transmission ratio.

[0179] S4 measures the vehicle's steering gear ratio based on the way the steering wheel is manually operated.

[0180] Specifically, the steering ratio of the vehicle is measured by manually operating the steering wheel, including:

[0181] S41: Control the vehicle speed between 20km / h and 25km / h. Manually operate the steering wheel to turn 90° to the left and maintain the steering wheel angle for 5 seconds. The rotation error is ±5°.

[0182] S42, collects 10 sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC system;

[0183] S43, calculate the turning radius R using the following formula L :

[0184] R L =RL y

[0185]

[0186] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0187] S44, calculate the steering transmission ratio I using the following formula:

[0188]

[0189]

[0190] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0191] S45, repeating S43 to S44, calculating 10 sets of steering gear ratios using the collected 10 sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the 10 sets of steering gear ratios;

[0192] S46: Control the vehicle speed to between 20 km / h and 25 km / h, manually operate the steering wheel, turn the steering wheel 90 degrees to the left again, and maintain the steering wheel angle for 5 seconds; then repeat S42 to S45; until the steering wheel is turned to the left at an angle of 360 degrees, obtain the average value of the four sets of steering transmission ratios; average the average values ​​of the four sets of steering transmission ratios to obtain the left steering transmission ratio;

[0193] S47: Control the vehicle speed between 20km / h and 25km / h, manually operate the steering wheel, turn the steering wheel 90° to the right, and maintain the steering wheel angle for 5 seconds;

[0194] S48, collects 10 sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC system;

[0195] S49, calculate the turning radius R using the following formula L :

[0196] R L =RL y

[0197]

[0198] Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value;

[0199] S410: Calculate the steering transmission ratio I using the following formula:

[0200]

[0201]

[0202] Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase;

[0203] S411, repeating S49 to S410, calculating 10 sets of steering gear ratios using the collected 10 sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average of the 10 sets of steering gear ratios;

[0204] S412: Control the vehicle speed between 20 km / h and 25 km / h, manually operate the steering wheel, turn the steering wheel 90 degrees to the right again, and maintain the steering wheel angle for 5 seconds; then repeat S48 to S411; until the steering wheel is turned 360 degrees to the right, obtain the average value of the four sets of steering transmission ratios; take the average value of the four sets of steering transmission ratios to obtain the right steering transmission ratio.

[0205] At this point, the left and right steering transmission ratios can be obtained through the method of this embodiment.

[0206] In summary, this embodiment provides a method for measuring a vehicle's steering ratio based on ESC self-learning calibration. Compared to existing steering ratio measurement methods, which require manual drawing of straight lines and curves on the ground and then manually measuring the distance, resulting in large errors and measuring only the ratio in one direction, this method has low measurement errors and directly uses sensors to acquire data, making it quick and convenient. Furthermore, this method can measure and process both left and right ratios. This method addresses issues such as steering performance changes caused by the steering and suspension performance of the front or rear axle of a vehicle, which can lead to understeer and oversteer control performance when the ESC or Onebox controls the vehicle and cause instability, as well as inaccurate automatic parking.

[0207] Moreover, it should be noted that, through the description of the above embodiments, those skilled in the art can clearly understand that the method according to the above embodiment can be implemented by means of software plus a necessary general hardware platform, or of course by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the method described in the embodiment of the present invention.

[0208] Second embodiment

[0209] This embodiment provides a device for measuring the steering gear ratio of a car based on ESC self-learning calibration. The device is used to implement the above embodiments and implementation methods, and the details that have been explained will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, it is also possible and conceivable to implement it in hardware, or a combination of software and hardware. Figure 5 As shown, the device includes: a self-learning instruction sending module, a verification module, a first steering transmission ratio measuring module and a second steering transmission ratio measuring module;

[0210] The self-learning instruction sending module is used to send a self-learning instruction to the ESC through the host computer after the vehicle to be tested drives to the test site, and trigger the verification module;

[0211] The verification module is used to determine whether the steering angle and the inertial measurement unit IMU are verified; if the steering angle and the inertial measurement unit are verified, the first steering transmission ratio measurement module is triggered; otherwise, the steering angle and the inertial measurement unit are verified;

[0212] The first steering transmission ratio measurement module is used to determine whether the vehicle under test has an active steering function. If the vehicle under test has an active steering function, the steering transmission ratio of the vehicle is measured based on the active steering function of the vehicle under test; otherwise, the second steering transmission ratio measurement module is triggered;

[0213] The second steering transmission ratio measurement module is used to measure the steering transmission ratio of the vehicle based on manual operation of the steering wheel.

[0214] It should be noted that the device for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration in this embodiment corresponds to the method for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration in the first embodiment mentioned above; wherein, the functions implemented by each functional module in the device for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration in this embodiment correspond one-to-one to each process step in the method for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration in the first embodiment mentioned above; therefore, they will not be repeated here.

[0215] In addition, it should be noted that the above-mentioned modules can be implemented through software or hardware. For the latter, it can be implemented in the following ways, but not limited to this: the above-mentioned modules are all located in the same processor; or the above-mentioned modules are located in different processors in any combination.

[0216] Third embodiment

[0217] This embodiment provides an electronic device comprising a processor and a memory; wherein the memory stores at least one instruction, which is loaded and executed by the processor to implement the method of the first embodiment described above. The electronic device may vary significantly due to different configurations or performance, and may comprise one or more processors and one or more memories, wherein the memory stores at least one instruction, which is loaded and executed by the processor to implement the method of the first embodiment.

[0218] Fourth embodiment

[0219] This embodiment provides a computer-readable storage medium storing at least one instruction, which is loaded and executed by a processor to implement the above-described method. The computer-readable storage medium may be a ROM, random access memory, CD-ROM, magnetic tape, floppy disk, or optical data storage device. The instructions stored therein can be loaded by a processor in a terminal to execute the method of the first embodiment.

[0220] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0221] In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0222] In the several embodiments provided by the present invention, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, and can be electrical or other forms.

[0223] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0224] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0225] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, etc. Various media that can store program codes.

[0226] Finally, it should be noted that the above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art could make numerous improvements and modifications without departing from the principles of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention. Therefore, the appended claims are intended to include the preferred embodiments and all variations and modifications that fall within the scope of the preferred embodiments.

Claims

1. A method for measuring the steering ratio of an automobile based on ESC self-learning calibration, characterized in that: The method for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration includes: S1: After the vehicle to be tested arrives at the test site, the host computer sends a self-learning instruction to the ESC (Electronic Stability Program), and then enters S2; S2, determine whether the steering angle and the inertial measurement unit (IMU) are calibrated. If the steering angle and the inertial measurement unit are calibrated, proceed to S3; otherwise, calibrate the steering angle and the inertial measurement unit. S3, determining whether the vehicle to be tested has an active steering function. If the vehicle to be tested has an active steering function, measuring the steering gear ratio of the vehicle based on the active steering function of the vehicle to be tested; otherwise, proceeding to S4; S4, measures the vehicle's steering gear ratio based on manual steering wheel operation; Measures the vehicle's steering ratio based on its active steering function, including: S31, controlling the vehicle speed within a second preset vehicle speed range, controlling the steering wheel to turn left 90° at a speed greater than a second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period; S32, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC; S33, calculate the turning radius R using the following formula L : R L =R-L y Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value; S34, calculate the steering transmission ratio I using the following formula: Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase; S35, repeating S33 to S34, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios; S36, controlling the vehicle speed within the second preset vehicle speed range, turning the steering wheel another 90° to the left at a speed greater than the second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period; then repeating S32 to S35 until the steering wheel has been turned leftwards 360°, obtaining an average value of the four sets of steering transmission ratios; averaging the average values ​​of the four sets of steering transmission ratios to obtain a left-hand steering transmission ratio; S37, controlling the vehicle speed to be within the second preset vehicle speed range, controlling the steering wheel to turn right 90° at a speed greater than the second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period; S38, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC; S39, calculate the turning radius R using the following formula L : R L =R-L y Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value; S310: Calculate the steering transmission ratio I using the following formula: Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase; S311, repeating S39 to S310, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios; S312: Control the vehicle speed within the second preset speed range, turn the steering wheel another 90° to the right at a speed greater than the second preset rotation speed, and maintain the steering wheel angle unchanged for a third preset time period; then repeat S38 to S311 until the steering wheel has been turned rightwards 360°, obtaining an average value of the four sets of steering gear ratios; and average the average values ​​of the four sets of steering gear ratios to obtain the right steering gear ratio. The vehicle's steering ratio is measured by manually operating the steering wheel, including: S41, controlling the vehicle speed within a third preset speed range and within a preset rotation error, manually operating the steering wheel to turn the steering wheel 90° to the left, and maintaining the steering wheel angle unchanged for a fourth preset time period; S42, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC; S43, calculate the turning radius R using the following formula L : R L =R-L y Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value; S44, calculate the steering transmission ratio I using the following formula: Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase; S45, repeating S43 to S44, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple sets of steering gear ratios; S46: Control the vehicle speed within the third preset speed range and manually operate the steering wheel to turn the steering wheel 90 degrees to the left again, and maintain the steering wheel angle unchanged for a fourth preset time period; then repeat S42 to S45 until the steering wheel is turned 360 degrees to the left, and then obtain an average value of the four sets of steering transmission ratios; and average the average values ​​of the four sets of steering transmission ratios to obtain the left steering transmission ratio. S47, controlling the vehicle speed within a third preset speed range, manually operating the steering wheel to turn the steering wheel 90° to the right, and maintaining the steering wheel angle unchanged for a fourth preset time period; S48, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC; S49, calculate the turning radius R using the following formula L : R L =R-L y Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value; S410: Calculate the steering transmission ratio I using the following formula: Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase; S411, repeating S49 to S410, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios; S412, control the vehicle speed within the third preset speed range, use manual steering wheel operation to turn the steering wheel to the right again 90°, and keep the steering wheel angle unchanged for a fourth preset time; then repeat S48 to S411; until the angle of the steering wheel turned to the right reaches 360°, obtain the average value of the four groups of steering transmission ratios; take the average value of the four groups of steering transmission ratios to obtain the right steering transmission ratio.

2. The method for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration according to claim 1, characterized in that: The calibrating of the steering angle and the inertial measurement unit includes: S21, controlling the vehicle to travel a preset distance in a straight line at a preset speed, maintaining the speed for a first preset time within an allowable error of the preset speed, and sending a heading angle zero point calibration command from the host computer to perform a heading angle zero point calibration. After the calibration is completed, the ESC collects multiple sets of heading angle values ​​within a second preset time; S22: If the average of the multiple sets of azimuth angle values ​​collected is within the first preset error interval, it is determined that the azimuth angle zero point calibration is successful. At this time, multiple sets of yaw angular velocities and lateral accelerations are collected and recorded, and the recorded yaw angular velocities and lateral accelerations are low-pass filtered. If the average of the multiple sets of yaw angular velocities after filtering is not within the second preset error interval or the average of the multiple sets of lateral accelerations after filtering is not within the third preset error interval, an IMU installation failure is reported. If the average of the multiple sets of yaw angular velocities after filtering is within the second preset error interval and the average of the multiple sets of lateral accelerations after filtering is within the third preset error interval, the average of the multiple sets of yaw angular velocities after filtering at this time is used as the yaw angular velocity compensation value, and the average of the multiple sets of lateral accelerations after filtering is used as the lateral acceleration compensation value, and then the process proceeds to S3. S23, if the average of the multiple sets of direction angle values ​​collected is not within the first preset error range, it is determined that the direction angle zero point check has failed, and the process returns to S21; S24: If the azimuth zero point calibration fails three times in a row, a fault is reported. If you want to continue the azimuth zero point calibration, you need to power on the control system again and then return to S21.

3. The method for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration according to claim 2, characterized in that: The calibration of the steering angle and the inertial measurement unit further includes: After the heading angle zero point calibration is completed, control the vehicle speed within the first preset vehicle speed range, turn the steering wheel to the left at a speed greater than the first preset rotation speed, and record whether the positive and negative values ​​of the longitudinal acceleration, lateral acceleration, heading angle and yaw angular velocity meet the measurement coordinate system to verify the effect of the heading angle zero point calibration.

4. A device for measuring the steering ratio of an automobile based on ESC self-learning calibration, characterized in that: The device for measuring the steering gear ratio of an automobile based on ESC self-learning calibration comprises: a self-learning instruction sending module, a verification module, a first steering gear ratio measuring module and a second steering gear ratio measuring module; The self-learning instruction sending module is used to send a self-learning instruction to the ESC through the host computer after the vehicle to be tested drives to the test site, and trigger the verification module; The verification module is used to determine whether the steering angle and the inertial measurement unit (IMU) are verified; if the steering angle and the inertial measurement unit are verified, the first steering transmission ratio measurement module is triggered; otherwise, the steering angle and the inertial measurement unit are verified until the steering angle and the inertial measurement unit are verified; The first steering transmission ratio measurement module is used to determine whether the vehicle under test has an active steering function. If the vehicle under test has an active steering function, the steering transmission ratio of the vehicle is measured based on the active steering function of the vehicle under test; otherwise, the second steering transmission ratio measurement module is triggered; The second steering gear ratio measurement module is used to measure the steering gear ratio of the vehicle based on manual operation of the steering wheel; The step of measuring the steering transmission ratio of the vehicle by the first steering transmission ratio measurement module based on the active steering function of the vehicle to be tested includes: S31, controlling the vehicle speed within a second preset vehicle speed range, controlling the steering wheel to turn left 90° at a speed greater than a second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period; S32, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC; S33, calculate the turning radius R using the following formula L : R L =R-L y Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value; S34, calculate the steering transmission ratio I using the following formula: Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase; S35, repeating S33 to S34, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios; S36, controlling the vehicle speed within the second preset vehicle speed range, turning the steering wheel another 90° to the left at a speed greater than the second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period; then repeating S32 to S35 until the steering wheel has been turned leftwards 360°, obtaining an average value of the four sets of steering transmission ratios; averaging the average values ​​of the four sets of steering transmission ratios to obtain a left-hand steering transmission ratio; S37, controlling the vehicle speed to be within the second preset vehicle speed range, controlling the steering wheel to turn right 90° at a speed greater than the second preset rotation speed, and maintaining the steering wheel angle unchanged for a third preset time period; S38, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC; S39, calculate the turning radius R using the following formula L : R L =R-L y Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value; S310: Calculate the steering transmission ratio I using the following formula: Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase; S311, repeating S39 to S310, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios; S312: Control the vehicle speed within the second preset speed range, turn the steering wheel another 90° to the right at a speed greater than the second preset rotation speed, and maintain the steering wheel angle unchanged for a third preset time period; then repeat S38 to S311 until the steering wheel has been turned rightwards 360°, obtaining an average value of the four sets of steering gear ratios; and average the average values ​​of the four sets of steering gear ratios to obtain the right steering gear ratio. The second steering transmission ratio measurement module is specifically configured to perform the following steps: S41, controlling the vehicle speed within a third preset speed range and within a preset rotation error, manually operating the steering wheel to turn the steering wheel 90° to the left, and maintaining the steering wheel angle unchanged for a fourth preset time period; S42, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC; S43, calculate the turning radius R using the following formula L : R L =R-L y Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value; S44, calculate the steering transmission ratio I using the following formula: Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase; S45, repeating S43 to S44, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple sets of steering gear ratios; S46: Control the vehicle speed within the third preset speed range and manually operate the steering wheel to turn the steering wheel 90 degrees to the left again, and maintain the steering wheel angle unchanged for a fourth preset time period; then repeat S42 to S45 until the steering wheel is turned 360 degrees to the left, and then obtain an average value of the four sets of steering transmission ratios; and average the average values ​​of the four sets of steering transmission ratios to obtain the left steering transmission ratio. S47, controlling the vehicle speed within a third preset speed range, manually operating the steering wheel to turn the steering wheel 90° to the right, and maintaining the steering wheel angle unchanged for a fourth preset time period; S48, collects multiple sets of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through ESC; S49, calculate the turning radius R using the following formula L : R L =R-L y Among them, L y is the distance between the IMU and the center of mass of the vehicle; v is the vehicle speed; ω is the yaw angular velocity; ω offset is the yaw rate compensation value; Ay is the lateral acceleration; Ay offset is the lateral acceleration compensation value; S410: Calculate the steering transmission ratio I using the following formula: Wherein, Lw is the steering wheel angle; L is the vehicle wheelbase; S411, repeating S49 to S410, calculating multiple steering gear ratios based on the collected multiple sets of vehicle speeds, yaw angular velocities, lateral accelerations, and steering wheel angles, and finding an average value of the multiple steering gear ratios; S412, control the vehicle speed within the third preset speed range, use manual steering wheel operation to turn the steering wheel to the right again 90°, and keep the steering wheel angle unchanged for a fourth preset time; then repeat S48 to S411; until the angle of the steering wheel turned to the right reaches 360°, obtain the average value of the four groups of steering transmission ratios; take the average value of the four groups of steering transmission ratios to obtain the right steering transmission ratio.

5. The device for measuring the steering gear ratio of an automobile based on ESC self-learning calibration according to claim 4, characterized in that: The step of the verification module verifying the steering angle and the inertial measurement unit includes: S21, controlling the vehicle to travel a preset distance in a straight line at a preset speed, maintaining the speed for a first preset time within an allowable error of the preset speed, and sending a heading angle zero point calibration command from the host computer to perform a heading angle zero point calibration. After the calibration is completed, the ESC collects multiple sets of heading angle values ​​within a second preset time; S22: If the average of the multiple sets of azimuth angle values ​​collected is within the first preset error interval, it is determined that the azimuth angle zero point calibration is successful. At this time, multiple sets of yaw angular velocities and lateral accelerations are collected and recorded, and the recorded yaw angular velocities and lateral accelerations are low-pass filtered. If the average of the multiple sets of yaw angular velocities after filtering is not within the second preset error interval or the average of the multiple sets of lateral accelerations after filtering is not within the third preset error interval, an IMU installation failure is reported. If the average of the multiple sets of yaw angular velocities after filtering is within the second preset error interval and the average of the multiple sets of lateral accelerations after filtering is within the third preset error interval, the average of the multiple sets of yaw angular velocities after filtering at this time is used as the yaw angular velocity compensation value, and the average of the multiple sets of lateral accelerations after filtering is used as the lateral acceleration compensation value, and then the process proceeds to S3. S23, if the average of the multiple sets of direction angle values ​​collected is not within the first preset error range, it is determined that the direction angle zero point check has failed, and the process returns to S21; S24: If the azimuth zero point calibration fails three times in a row, a fault is reported. If you want to continue the azimuth zero point calibration, you need to power on the control system again and then return to S21.

6. The device for measuring the steering gear ratio of an automobile based on ESC self-learning calibration according to claim 5, characterized in that: The verification module is also used for: After the heading angle zero point calibration is completed, control the vehicle speed within the first preset vehicle speed range, turn the steering wheel to the left at a speed greater than the first preset rotation speed, and record whether the positive and negative values ​​of the longitudinal acceleration, lateral acceleration, heading angle and yaw angular velocity meet the measurement coordinate system to verify the effect of the heading angle zero point calibration.

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