CN117784745A - Method and device for measuring steering transmission ratio of automobile based on ESC self-learning calibration - Google Patents

Abstract

The invention provides a method and a device for measuring steering transmission ratio of an automobile based on ESC self-learning calibration, belonging to the technical field of vehicle engineering, wherein the method comprises the following steps: s1, after a vehicle to be tested runs to a test site, a self-learning instruction is sent to an electronic stability system ESC through an upper computer, and then S2 is entered; s2, judging whether the steering angle and the inertia measurement unit are checked; if the verification is completed, entering S3; otherwise, checking the steering angle and the inertia measurement unit; s3, judging whether the vehicle to be tested has an active steering function, if so, measuring the steering transmission ratio of the vehicle based on the active steering function of the vehicle to be tested; otherwise, entering S4; s4, measuring the steering transmission ratio of the vehicle by adopting a mode of manually operating the steering wheel. The invention has small measurement error, is quick and convenient to implement, and can measure the left and right rotation ratios.

Description

Method and device for measuring steering transmission ratio of automobile based on ESC self-learning calibration

Technical Field

The invention relates to the technical field of vehicle engineering, in particular to a method and a device for measuring an automobile steering transmission ratio based on ESC self-learning calibration.

Background

At present, requirements on safety and comfort of automobile braking are higher and higher, and more automobiles begin to be provided with electronic braking products, for example. An electronic stability system (Electronic Stability Program, ESC), a brake-by-wire system Onebox and an automatic parking system, wherein the products all need steering transmission ratio; wherein, steering transmission ratio, namely steering system angle transmission ratio, refers to: the ratio of the steering angle of the steering wheel to the steering wheel deflection angle on the same side of the steering wheel is generally indicated by iw. I.e. the product of the steering gear angle ratio i1 and the steering gear angle ratio i2, if rotating the steering wheel a revolution (360 degrees) would result in steering the wheels 20 degrees, the steering gear ratio is equal to 360 divided by 20, i.e. 18:1. The steering gear ratio parameters directly influence the control performance of the ESC or Onebox, and the unreasonable steering gear ratio setting can cause the understeer of the vehicle or oversteer, which is easy to cause the runaway of the vehicle and cause loss of life and property. In addition, the steering gear ratio parameter directly participates in the calculation of the electronic stability control system, so that the calculation of the Ackerman angle is directly influenced, and the Ackerman angle influences the calculation of the target yaw rate, so that the calculation of the vehicle operation stability braking force or the calculation of the automatic parking steering angle are influenced.

For all new model vehicles with the following new characteristics, the ESC learning process of the steering ratio characteristic needs to be carried out: the steering performance changes due to the steering of the front axle or the rear axle, the suspension performance: the new steering engine of the front axle, steering link change, left rudder or right rudder turn, turn (the additional axle) has the self-steering influence after the axle configuration of the additional axle of turning, whether to influence the turning performance to the new car type, in case of any doubt, propose to turn to the ratio learning flow. After the steering transmission ratio is self-learned, parameters are written into an Electronic Control Unit (ECU) of the automobile, so that the control parameters can be optimized, the stability of the automobile in the ESC control process is improved, and meanwhile, the comfort, the safety and the automatic parking accuracy of the automobile are improved.

At present, a steering wheel transmission ratio automatic calibration method and a steering wheel transmission ratio automatic calibration method are disclosed in literature, but the two schemes need to draw straight lines and curves on the ground manually, then the distance is measured manually, the error in the whole process is large, and only the rotation ratio in one direction can be measured, but the left and right rotation ratios are different in practice. Therefore, the existing automobile steering transmission ratio measurement scheme has the problems that the error is large, the measurement result is single, and the actual requirements cannot be met.

Disclosure of Invention

The embodiment of the invention provides a method and a device for measuring an automobile steering transmission ratio based on ESC self-learning calibration, which are used for solving the technical problems that the existing automobile steering transmission ratio measurement scheme has large error and single measurement result and cannot meet actual requirements.

In order to solve the technical problems, the embodiment of the invention provides the following technical scheme:

in one aspect, the embodiment of the invention provides a method for measuring the steering transmission ratio of an automobile based on ESC self-learning calibration, which comprises the following steps:

s1, after a vehicle to be tested runs to a test site, a self-learning instruction is sent to an ESC (Electronic Stability Program, electronic stability system) through an upper computer, and then S2 is entered;

s2, judging whether the steering angle and the inertial measurement unit IMU are checked; if the steering angle and the inertia measurement unit are checked, entering S3; otherwise, checking the steering angle and the inertia measurement unit;

s3, judging whether the vehicle to be tested has an active steering function, and if the vehicle to be tested has the active steering function, measuring the steering transmission ratio of the vehicle based on the active steering function of the vehicle to be tested; otherwise, entering S4;

S4, measuring the steering transmission ratio of the vehicle based on the mode of manually operating the steering wheel.

Optionally, the verifying the steering angle and the inertia measurement unit includes:

s21, controlling the vehicle to linearly travel for a preset distance at a preset speed, keeping the speed within a preset speed allowable error for a first preset time, sending a direction angle zero point checking command by an upper computer, performing direction angle zero point checking, and acquiring a plurality of groups of direction angle values within a second preset time by an ESC after checking;

s22, if the average value of the collected multiple groups of direction angle values is in a first preset error interval, determining that the direction angle zero point verification is successful, collecting and recording multiple groups of yaw rates and lateral accelerations at the moment, carrying out low-pass filtering on the recorded yaw rates and lateral accelerations, if the average value of the filtered multiple groups of yaw rates is not in a second preset error interval or the average value of the filtered multiple groups of lateral accelerations is not in a third preset error interval, reporting that an IMU installation fault occurs, and if the average value of the filtered multiple groups of yaw rates is in the second preset error interval and the average value of the filtered multiple groups of lateral accelerations is in the third preset error interval, taking the average value of the filtered multiple groups of yaw rates at the moment as a yaw rate compensation value, taking the average value of the filtered multiple groups of lateral accelerations as a lateral acceleration compensation value, and then entering S3;

S23, if the average value of the collected multiple groups of direction angle values is not in the first preset error interval, determining that the direction angle zero point verification fails, and returning to S21 at the moment;

and S24, if the continuous three-time direction angle zero point verification fails, reporting that the fault occurs, and if the continuous three-time direction angle zero point verification is required, controlling the system to be powered on again, and returning to S21.

Optionally, the verifying the steering angle and the inertia measurement unit further includes:

after the zero point verification of the direction angle is finished, controlling the vehicle speed to rotate the steering wheel leftwards in a first preset vehicle speed interval at a speed larger than the first preset rotating speed, and recording whether the positive and negative of the longitudinal acceleration, the lateral acceleration, the direction angle and the yaw angular velocity meet a measurement coordinate system or not so as to verify the zero point verification effect of the direction angle.

Optionally, measuring a steering gear ratio of the vehicle based on an active steering function of the vehicle under test includes:

s31, controlling the vehicle speed to be in a second preset vehicle speed interval, controlling the steering wheel to turn 90 degrees leftwards at a speed greater than a second preset rotating speed, and keeping the angle of the steering wheel unchanged for a third preset time period;

s32, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

S33, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s34, the steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s35, repeating the steps S33 to S34, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s36, controlling the vehicle speed to be in a second preset vehicle speed interval, turning the steering wheel to the left by 90 degrees again at a speed greater than a second preset rotation speed, and keeping the angle of the steering wheel unchanged for a third preset time period; then repeating S32 to S35; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; taking an average value of the average values of the steering transmission ratios of the 4 groups to obtain a left steering transmission ratio;

s37, controlling the speed of the vehicle in a second preset vehicle speed interval, controlling the steering wheel to turn 90 degrees rightwards at a speed greater than the second preset rotating speed, and keeping the angle of the steering wheel unchanged for a third preset time period;

S38, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s39, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s310, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s311, repeating S39 to S310, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s312, controlling the vehicle speed to be in a second preset vehicle speed interval, turning the steering wheel to the right by 90 degrees again at a speed greater than a second preset rotation speed, and keeping the steering wheel angle unchanged for a third preset time period; then repeating S38 to S311; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns rightwards until the angle reaches 360 degrees; and taking an average value of the average values of the steering transmission ratios of the 4 groups to obtain the steering transmission ratio in the right direction.

Optionally, the method for measuring the steering transmission ratio of the vehicle by manually operating the steering wheel comprises the following steps:

S41, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the left by 90 degrees in a manual steering wheel operation mode in a preset rotation error, and keeping the steering wheel angle unchanged for a fourth preset time period;

s42, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s43, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s44, calculating a steering transmission ratio I through the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s45, repeating the steps S43 to S44, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s46, controlling the speed of the vehicle in a third preset vehicle speed interval, turning the steering wheel to the left by 90 degrees again by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period; then repeating S42 to S45; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; taking an average value of the average values of the steering transmission ratios of the 4 groups to obtain a left steering transmission ratio;

S47, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the right by 90 degrees by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period;

s48, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s49, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s410, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s411, repeating S49 to S410, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s412, controlling the speed of the vehicle in a third preset vehicle speed interval, turning the steering wheel to the right by 90 degrees again by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period; then repeating S48 to S411; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns rightwards until the angle reaches 360 degrees; and taking an average value of the average values of the steering transmission ratios of the 4 groups to obtain the steering transmission ratio in the right direction.

On the other hand, the invention also provides a device for measuring the steering transmission ratio of the automobile based on the ESC self-learning calibration, which comprises: the device comprises a self-learning instruction sending module, a checking module, a first steering transmission ratio measuring module and a second steering transmission ratio measuring module;

the self-learning instruction sending module is used for sending a self-learning instruction to the ESC through the upper computer after the vehicle to be tested runs to the test site, and triggering the verification module;

the checking module is used for judging whether the steering angle and the inertial measurement unit IMU are checked; triggering the first steering transmission ratio measuring module if the steering angle and the inertia measuring unit are checked; otherwise, checking the steering angle and the inertia measurement unit;

the first steering transmission ratio measuring module is used for judging whether the vehicle to be measured has an active steering function, and if the vehicle to be measured has the active steering function, the steering transmission ratio of the vehicle is measured based on the active steering function of the vehicle to be measured; otherwise, triggering the second steering transmission ratio measuring module;

the second steering gear ratio measuring module is used for measuring the steering gear ratio of the vehicle based on a mode of manually operating the steering wheel.

Optionally, the step of verifying the steering angle and the inertia measurement unit by the verification module includes:

S21, controlling the vehicle to linearly travel for a preset distance at a preset speed, keeping the speed within a preset speed allowable error for a first preset time, sending a direction angle zero point checking command by an upper computer, performing direction angle zero point checking, and acquiring a plurality of groups of direction angle values within a second preset time by an ESC after checking;

s22, if the average value of the collected multiple groups of direction angle values is in a first preset error interval, determining that the direction angle zero point verification is successful, collecting and recording multiple groups of yaw rates and lateral accelerations at the moment, carrying out low-pass filtering on the recorded yaw rates and lateral accelerations, if the average value of the filtered multiple groups of yaw rates is not in a second preset error interval or the average value of the filtered multiple groups of lateral accelerations is not in a third preset error interval, reporting that an IMU installation fault occurs, and if the average value of the filtered multiple groups of yaw rates is in the second preset error interval and the average value of the filtered multiple groups of lateral accelerations is in the third preset error interval, taking the average value of the filtered multiple groups of yaw rates at the moment as a yaw rate compensation value, taking the average value of the filtered multiple groups of lateral accelerations as a lateral acceleration compensation value, and then entering S3;

S23, if the average value of the collected multiple groups of direction angle values is not in the first preset error interval, determining that the direction angle zero point verification fails, and returning to S21 at the moment;

and S24, if the continuous three-time direction angle zero point verification fails, reporting that the fault occurs, and if the continuous three-time direction angle zero point verification is required, controlling the system to be powered on again, and returning to S21.

Optionally, the verification module is further configured to:

after the zero point verification of the direction angle is finished, controlling the vehicle speed to rotate the steering wheel leftwards in a first preset vehicle speed interval at a speed larger than the first preset rotating speed, and recording whether the positive and negative of the longitudinal acceleration, the lateral acceleration, the direction angle and the yaw angular velocity meet a measurement coordinate system or not so as to verify the zero point verification effect of the direction angle.

Optionally, the step of measuring the steering gear ratio of the vehicle based on the active steering function of the vehicle under test by the first steering gear ratio measurement module includes:

s31, controlling the vehicle speed to be in a second preset vehicle speed interval, controlling the steering wheel to turn 90 degrees leftwards at a speed greater than a second preset rotating speed, and keeping the angle of the steering wheel unchanged for a third preset time period;

s32, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

S33, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s34, the steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s35, repeating the steps S33 to S34, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s36, controlling the vehicle speed to be in a second preset vehicle speed interval, turning the steering wheel to the left by 90 degrees again at a speed greater than a second preset rotation speed, and keeping the angle of the steering wheel unchanged for a third preset time period; then repeating S32 to S35; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; taking an average value of the average values of the steering transmission ratios of the 4 groups to obtain a left steering transmission ratio;

s37, controlling the speed of the vehicle in a second preset vehicle speed interval, controlling the steering wheel to turn 90 degrees rightwards at a speed greater than the second preset rotating speed, and keeping the angle of the steering wheel unchanged for a third preset time period;

S38, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s39, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s310, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s311, repeating S39 to S310, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s312, controlling the vehicle speed to be in a second preset vehicle speed interval, turning the steering wheel to the right by 90 degrees again at a speed greater than a second preset rotation speed, and keeping the steering wheel angle unchanged for a third preset time period; then repeating S38 to S311; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns rightwards until the angle reaches 360 degrees; and taking an average value of the average values of the steering transmission ratios of the 4 groups to obtain the steering transmission ratio in the right direction.

Optionally, the second steering gear ratio measurement module is specifically configured to perform the following steps:

S41, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the left by 90 degrees in a manual steering wheel operation mode in a preset rotation error, and keeping the steering wheel angle unchanged for a fourth preset time period;

s42, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s43, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s44, calculating a steering transmission ratio I through the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s45, repeating the steps S43 to S44, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s46, controlling the speed of the vehicle in a third preset vehicle speed interval, turning the steering wheel to the left by 90 degrees again by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period; then repeating S42 to S45; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; taking an average value of the average values of the steering transmission ratios of the 4 groups to obtain a left steering transmission ratio;

S47, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the right by 90 degrees by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period;

s48, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s49, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s410, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s411, repeating S49 to S410, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s412, controlling the speed of the vehicle in a third preset vehicle speed interval, turning the steering wheel to the right by 90 degrees again by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period; then repeating S48 to S411; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns rightwards until the angle reaches 360 degrees; and taking an average value of the average values of the steering transmission ratios of the 4 groups to obtain the steering transmission ratio in the right direction.

In yet another aspect, the present invention also provides an electronic device including a processor and a memory; at least one instruction is stored in the memory, loaded and executed by the processor to implement the above-described method.

In yet another aspect, the present invention also provides a computer readable storage medium having at least one instruction stored therein, the instruction being loaded and executed by a processor to implement the above method.

The technical scheme provided by the invention has the beneficial effects that at least:

compared with the existing automobile steering transmission ratio measurement scheme that straight lines and curves are drawn on the ground manually, and then distances are measured manually, the whole process is large in error and can only measure the rotation ratio in one direction. The problems of incorrect position parking caused by understeer, oversteer control performance and automatic parking inaccuracy when the ESC and Onebox control vehicles are unstable due to the change of steering performance caused by the steering and suspension performance of the front axle or the rear axle of the vehicles are solved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:

FIG. 1 is a schematic flow chart illustrating an embodiment of a method for measuring a steering gear ratio of an automobile based on ESC self-learning calibration;

FIG. 2 is a detailed flow chart of a method for measuring the steering gear ratio of an automobile based on ESC self-learning calibration according to an embodiment of the present invention;

FIG. 3 is a schematic illustration of a vehicle steering travel model;

FIG. 4 is a schematic illustration of a bicycle model of a vehicle steering;

fig. 5 is a system block diagram of an apparatus for measuring steering gear ratio of an automobile based on ESC self-learning calibration in accordance with an embodiment of the present invention.

Detailed Description

In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.

Moreover, it should be noted that the terms first, second, etc. in the description and the claims of the present invention and the related drawings are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

First embodiment

Aiming at the problems that the existing automobile steering transmission ratio measurement scheme has large error and single measurement result and cannot meet the actual requirements, the embodiment provides a method for measuring the automobile steering transmission ratio based on ESC self-learning calibration, which relates to products such as ESC, onebox line control braking, automatic parking and the like in the automobile active braking safety field of commercial vehicles and passenger vehicles; the method of the present embodiment may be implemented by an electronic device, and specifically, an execution flow of the method is shown in fig. 1, and includes the following flow steps:

S1, after a vehicle to be tested runs to a test site, a self-learning instruction is sent to an ESC (Electronic Stability Program, electronic stability system) through an upper computer, and then S2 is entered;

wherein the test field is generally a flat large square.

S2, judging whether the steering angle (Steering Angle Sensor, SAS) and the inertial measurement unit (Inertial measurement unit, IMU) are verified; if the SAS and IMU verification is completed, entering S3; otherwise, checking the SAS and the IMU until the checking is completed; the specific verification process is as follows:

s21, controlling the vehicle to run for 250m in a straight line at a speed of 20km/h, when the speed is between 19km/h and 21km/h, keeping the speed for 3 seconds, sending a direction angle zero point checking command by an upper computer, performing direction angle zero point checking, and acquiring 10 groups of direction angle values within 10 seconds by an ESC system after checking is completed;

s22, if the average value of the acquired 10 groups of direction angle values is between minus 10 degrees and plus 10 degrees, determining that the direction angle zero point verification is successful, acquiring and recording 10 groups of yaw rate Yaw rate and lateral acceleration Ay, carrying out low-pass filtering on the recorded Yaw rate and Ay, and if the average value of the 10 groups of yaw rate after filtering is not between minus 1.5 degrees and plus 1.5 degrees or the average value of the 10 groups of lateral acceleration after filtering is not between minus 1m/S ² To +1m/s ² Between, an IMU installation failure is reported if the filtered 10 sets of yaw rates have an average value between-1.5 DEG and +1.5 DEG and the filtered 10 sets of lateral accelerations are at-1 m/s ² To +1m/s ² Taking the average value of the 10 groups of yaw rates after filtering at the moment as a yaw rate compensation value and taking the average value of the 10 groups of lateral accelerations after filtering as lateral accelerationThe degree compensation value is then entered into S3;

s23, if the average value of the acquired 10 groups of direction angle values is not between-10 degrees and +10 degrees, determining that the direction angle zero point verification fails, and returning to S21 at the moment;

and S24, if the continuous three-time direction angle zero point verification fails, reporting that the fault occurs, and if the continuous three-time direction angle zero point verification is required, controlling the system to be powered on again, and returning to S21.

In addition, in the present embodiment, the verification of the steering angle and the inertia measurement unit further includes: after the zero point calibration of the direction angle is completed, controlling the vehicle speed to turn the steering wheel leftwards at a speed of more than 350 degrees/s from 0-20km/h, recording whether the positive and negative of the longitudinal acceleration, the lateral acceleration, the direction angle and the yaw angle speed meet a measurement coordinate system, and if the positive and negative of the longitudinal acceleration, the lateral acceleration, the direction angle and the yaw angle meet the measurement coordinate system, indicating that the zero point calibration of the direction angle is successful.

S3, judging whether the vehicle to be tested has an active steering function, and if the vehicle to be tested has the active steering function, measuring the steering transmission ratio of the vehicle based on the active steering function of the vehicle to be tested; otherwise, entering S4;

specifically, as shown in fig. 2, measuring the steering gear ratio of the vehicle based on the active steering function of the vehicle to be measured includes:

s31, controlling the speed of the vehicle to be between 20km/h and 25km/h, controlling the steering wheel to turn left by 90 degrees at a speed of more than 150 degrees/S, and keeping the angle of the steering wheel for 4 seconds;

s32, collecting 10 groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through an ESC system;

s33, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is the lateral addition ofA speed; ay _offset Is a lateral acceleration compensation value;

s34, the steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle; the vehicle steering travel model is shown in fig. 3, and when the vehicle model is converted into the bicycle model, δ is the steering angle of the front wheels, as shown in fig. 4.

S35, repeating the steps S33 to S34, calculating 10 groups of steering transmission ratios through the acquired 10 groups of vehicle speeds, yaw rates, lateral accelerations and steering wheel angles, and calculating an average value of the 10 groups of steering transmission ratios;

S36, controlling the speed of the vehicle to be between 20km/h and 25km/h, turning the steering wheel to the left by 90 degrees again at a speed of more than 150 degrees/S, and keeping the angle of the steering wheel for 4 seconds; then repeating S32 to S35; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; averaging the obtained average value of the 4 groups of steering transmission ratios to obtain a left steering transmission ratio;

s37, controlling the speed of the vehicle to be between 20km/h and 25km/h, controlling the steering wheel to turn 90 degrees to the right at a speed of more than 150 degrees/S, and keeping the angle of the steering wheel for 4 seconds;

s38, collecting 10 groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through an ESC system;

s39, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s310, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s311, repeating S39 to S310, calculating 10 groups of steering transmission ratios through the acquired 10 groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating the average value of the 10 groups of steering transmission ratios;

S312, controlling the speed of the vehicle to be between 20km/h and 25km/h, turning the steering wheel to the right by 90 degrees again at a speed of more than 150 degrees/S, and keeping the angle of the steering wheel for 4 seconds; then repeating S38 to S311; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns rightwards until the angle reaches 360 degrees; and taking an average value of the obtained average value of the 4 groups of steering transmission ratios to obtain the steering transmission ratio in the right direction.

S4, measuring the steering transmission ratio of the vehicle based on the mode of manually operating the steering wheel.

Specifically, a steering gear ratio of a vehicle is measured by manually operating a steering wheel, including:

s41, controlling the speed of the vehicle to be between 20km/h and 25km/h, turning the steering wheel to the left by 90 degrees in a manual steering wheel operation mode, and keeping the steering wheel angle for 5 seconds; wherein, the rotation error is +/-5 degrees;

s42, collecting 10 groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through an ESC system;

s43, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s44, calculating a steering transmission ratio I through the following formula:

Lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s45, repeating S43 to S44, calculating 10 groups of steering transmission ratios through the acquired 10 groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the 10 groups of steering transmission ratios;

s46, controlling the speed of the vehicle to be between 20km/h and 25km/h, turning the steering wheel to the left by 90 degrees again in a manual steering wheel operation mode, and keeping the steering wheel angle for 5 seconds; then repeating S42 to S45; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; averaging the obtained average value of the 4 groups of steering transmission ratios to obtain a left steering transmission ratio;

s47, controlling the speed of the vehicle to be between 20km/h and 25km/h, turning the steering wheel to the right by 90 degrees in a manual steering wheel operation mode, and keeping the steering wheel angle for 5 seconds;

s48, acquiring 10 groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC system;

s49, calculating by the following formulaRadius of turning R _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s410, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s411, repeating S49 to S410, calculating 10 groups of steering transmission ratios through the acquired 10 groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating the average value of the 10 groups of steering transmission ratios;

s412, controlling the speed of the vehicle to be between 20km/h and 25km/h, turning the steering wheel to the right by 90 degrees again by adopting a manual steering wheel operation mode, and keeping the steering wheel angle for 5 seconds; then repeating S48 to S411; obtaining an average value of 4 groups of steering transmission ratios after the steering wheel turns rightwards until the angle reaches 360 degrees; and taking an average value of the obtained average value of the 4 groups of steering transmission ratios to obtain the steering transmission ratio in the right direction.

Thus, the steering transmission ratio in the left-right direction can be obtained by the method of the embodiment.

In summary, compared with the existing automobile steering transmission ratio measurement scheme which requires manually drawing straight lines and curves on the ground and then manually measuring the distance, the method has the advantages that the error in the whole process is large, only one direction of rotation ratio can be measured, the measurement error is small, the sensor is directly adopted to obtain data, and the method has the characteristics of rapidness and convenience, and can be used for measuring the left and right rotation ratios. The problems of understeer, oversteer control performance, automatic parking inaccuracy and the like caused by the fact that steering performance changes due to steering or suspension performance of a front axle or a rear axle of a vehicle and the ESC and Onebox control the vehicle to be unstable are solved.

Moreover, it should be noted that, from the foregoing description of the embodiments, those skilled in the art will clearly understand that the method according to the above embodiment may be implemented by means of software plus a necessary general hardware platform, and of course may also be implemented by means of hardware, but in many cases the former is a preferred embodiment. Based on such understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art in the form of a software product stored in a storage medium (e.g. ROM/RAM, magnetic disk, optical disk) comprising instructions for causing a terminal device (which may be a mobile phone, a computer, a server, or a network device, etc.) to perform the method according to the embodiment of the present invention.

Second embodiment

The embodiment provides a device for measuring steering transmission ratio of an automobile based on self-learning calibration of an ESC, which is used for realizing the above embodiment and implementation, and is not described again. As used below, the term "module" may be a combination of software and/or hardware that implements a predetermined function. While the means described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated. As shown in fig. 5, the apparatus includes: the device comprises a self-learning instruction sending module, a checking module, a first steering transmission ratio measuring module and a second steering transmission ratio measuring module;

The self-learning instruction sending module is used for sending a self-learning instruction to the ESC through the upper computer after the vehicle to be tested runs to the test site, and triggering the verification module;

the checking module is used for judging whether the steering angle and the inertia measurement unit I MU are checked; triggering the first steering transmission ratio measuring module if the steering angle and the inertia measuring unit are checked; otherwise, checking the steering angle and the inertia measurement unit;

the first steering transmission ratio measuring module is used for judging whether the vehicle to be measured has an active steering function, and if the vehicle to be measured has the active steering function, the steering transmission ratio of the vehicle is measured based on the active steering function of the vehicle to be measured; otherwise, triggering the second steering transmission ratio measuring module;

the second steering gear ratio measuring module is used for measuring the steering gear ratio of the vehicle based on a mode of manually operating the steering wheel.

It should be noted that, the device for measuring the steering transmission ratio of the automobile based on the ESC self-learning calibration in the embodiment corresponds to the method for measuring the steering transmission ratio of the automobile based on the ESC self-learning calibration in the first embodiment; the functions realized by the functional modules in the device for measuring the steering transmission ratio of the automobile based on the ESC self-learning calibration in the embodiment are in one-to-one correspondence with the flow steps in the method for measuring the steering transmission ratio of the automobile based on the ESC self-learning calibration in the first embodiment; therefore, the description is omitted here.

In addition, it should be noted that each of the above modules may be implemented by software or hardware, and for the latter, it may be implemented by, but not limited to: the modules are all located in the same processor; alternatively, the above modules may be located in different processors in any combination.

Third embodiment

The embodiment provides an electronic device, which comprises a processor and a memory; wherein the memory stores at least one instruction, and the instruction is loaded and executed by the processor to implement the method of the first embodiment. The electronic device may vary considerably in configuration or performance and may include one or more processors and one or more memories in which at least one instruction is stored that is loaded by a processor and that performs the method of the first embodiment.

Fourth embodiment

The present embodiment provides a computer-readable storage medium having stored therein at least one instruction that is loaded and executed by a processor to implement the above-described method. The computer readable storage medium may be, among other things, ROM, random access memory, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. The instructions stored therein may be loaded by a processor in the terminal and perform the method of the first embodiment.

The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.

In the foregoing embodiments of the present invention, the descriptions of the embodiments are emphasized, and for a portion of this disclosure that is not described in detail in this embodiment, reference is made to the related descriptions of other embodiments.

In the several embodiments provided in the present invention, it should be understood that the disclosed technology may be implemented in other manners. The above-described embodiments of the apparatus are merely exemplary, and the division of the units, such as the division of the units, is merely a logical function division, and may be implemented in another manner, for example, multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interfaces, units or modules, or may be in electrical or other forms.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a Read-only Memory (ROM), a random access Memory (RAM, random Access Memory), a removable hard disk, a magnetic disk, or an optical disk, or other various media capable of storing program codes.

Finally, it should be noted that the above is only a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all alterations and modifications as fall within the scope of the preferred embodiments.

Claims (10)

1. The method for measuring the steering transmission ratio of the automobile based on the ESC self-learning calibration is characterized by comprising the following steps of:

s1, after a vehicle to be tested runs to a test site, a self-learning instruction is sent to an ESC (Electronic Stability Program, electronic stability system) through an upper computer, and then S2 is entered;

s2, judging whether the steering angle and the inertial measurement unit IMU are checked; if the steering angle and the inertia measurement unit are checked, entering S3; otherwise, checking the steering angle and the inertia measurement unit;

s3, judging whether the vehicle to be tested has an active steering function, and if the vehicle to be tested has the active steering function, measuring the steering transmission ratio of the vehicle based on the active steering function of the vehicle to be tested; otherwise, entering S4;

S4, measuring the steering transmission ratio of the vehicle based on the mode of manually operating the steering wheel.

2. The method for measuring a steering gear ratio of an automobile based on ESC self-learning calibration according to claim 1, wherein said checking the steering angle and inertia measurement unit comprises:

s21, controlling the vehicle to linearly travel for a preset distance at a preset speed, keeping the speed within a preset speed allowable error for a first preset time, sending a direction angle zero point checking command by an upper computer, performing direction angle zero point checking, and acquiring a plurality of groups of direction angle values within a second preset time by an ESC after checking;

s22, if the average value of the collected multiple groups of direction angle values is in a first preset error interval, determining that the direction angle zero point verification is successful, collecting and recording multiple groups of yaw rates and lateral accelerations at the moment, carrying out low-pass filtering on the recorded yaw rates and lateral accelerations, if the average value of the filtered multiple groups of yaw rates is not in a second preset error interval or the average value of the filtered multiple groups of lateral accelerations is not in a third preset error interval, reporting that an IMU installation fault occurs, and if the average value of the filtered multiple groups of yaw rates is in the second preset error interval and the average value of the filtered multiple groups of lateral accelerations is in the third preset error interval, taking the average value of the filtered multiple groups of yaw rates at the moment as a yaw rate compensation value, taking the average value of the filtered multiple groups of lateral accelerations as a lateral acceleration compensation value, and then entering S3;

S23, if the average value of the collected multiple groups of direction angle values is not in the first preset error interval, determining that the direction angle zero point verification fails, and returning to S21 at the moment;

and S24, if the continuous three-time direction angle zero point verification fails, reporting that the fault occurs, and if the continuous three-time direction angle zero point verification is required, controlling the system to be powered on again, and returning to S21.

3. The method for measuring a steering gear ratio of an automobile based on ESC self-learning calibration according to claim 2, wherein said checking the steering angle and inertia measurement unit further comprises:

after the zero point verification of the direction angle is finished, controlling the vehicle speed to rotate the steering wheel leftwards in a first preset vehicle speed interval at a speed larger than the first preset rotating speed, and recording whether the positive and negative of the longitudinal acceleration, the lateral acceleration, the direction angle and the yaw angular velocity meet a measurement coordinate system or not so as to verify the zero point verification effect of the direction angle.

4. The method for measuring the steering gear ratio of the vehicle based on the ESC self-learning calibration according to claim 2, characterized in that it comprises the steps of:

s31, controlling the vehicle speed to be in a second preset vehicle speed interval, controlling the steering wheel to turn 90 degrees leftwards at a speed greater than a second preset rotating speed, and keeping the angle of the steering wheel unchanged for a third preset time period;

S32, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s33, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s34, the steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s35, repeating the steps S33 to S34, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s36, controlling the vehicle speed to be in a second preset vehicle speed interval, turning the steering wheel to the left by 90 degrees again at a speed greater than a second preset rotation speed, and keeping the angle of the steering wheel unchanged for a third preset time period; then repeating S32 to S35; obtaining an average value of four groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; taking an average value of the average values of the four groups of steering transmission ratios to obtain a left steering transmission ratio;

s37, controlling the vehicle speed to be in a second preset vehicle speed interval, controlling the steering wheel to turn 90 degrees rightwards at a speed greater than a second preset rotating speed, and keeping the angle of the steering wheel unchanged for a third preset time period;

S38, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s39, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s310, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s311, repeating S39 to S310, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s312, controlling the vehicle speed to be in a second preset vehicle speed interval, turning the steering wheel to the right by 90 degrees again at a speed greater than a second preset rotation speed, and keeping the steering wheel angle unchanged for a third preset time period; then repeating S38 to S311; obtaining an average value of four groups of steering transmission ratios after the steering wheel turns to the right until the angle reaches 360 degrees; and taking an average value of the average values of the four groups of steering transmission ratios to obtain the steering transmission ratio in the right direction.

5. The method for measuring the steering gear ratio of the automobile based on the ESC self-learning calibration according to claim 2, wherein the method for measuring the steering gear ratio of the automobile by manually operating the steering wheel comprises:

S41, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the left by 90 degrees in a manual steering wheel operation mode in a preset rotation error, and keeping the steering wheel angle unchanged for a fourth preset time period;

s42, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s43, calculating the steering direction by the following formulaRadius R _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s44, calculating a steering transmission ratio I through the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s45, repeating the steps S43 to S44, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s46, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the left by 90 degrees again by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period; then repeating S42 to S45; obtaining an average value of four groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; taking an average value of the average values of the four groups of steering transmission ratios to obtain a left steering transmission ratio;

S47, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the right by 90 degrees by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period;

s48, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s49, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s410, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s411, repeating S49 to S410, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s412, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the right by 90 degrees again by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period; then repeating S48 to S411; obtaining an average value of four groups of steering transmission ratios after the steering wheel turns to the right until the angle reaches 360 degrees; and taking an average value of the average values of the four groups of steering transmission ratios to obtain the steering transmission ratio in the right direction.

6. The device for measuring the steering transmission ratio of the automobile based on the ESC self-learning calibration is characterized by comprising the following components: the device comprises a self-learning instruction sending module, a checking module, a first steering transmission ratio measuring module and a second steering transmission ratio measuring module;

the self-learning instruction sending module is used for sending a self-learning instruction to the ESC through the upper computer after the vehicle to be tested runs to the test site, and triggering the verification module;

the checking module is used for judging whether the steering angle and the inertial measurement unit IMU are checked; triggering the first steering transmission ratio measuring module if the steering angle and the inertia measuring unit are checked; otherwise, checking the steering angle and the inertia measurement unit until the checking of the steering angle and the inertia measurement unit is completed;

the first steering transmission ratio measuring module is used for judging whether the vehicle to be measured has an active steering function, and if the vehicle to be measured has the active steering function, the steering transmission ratio of the vehicle is measured based on the active steering function of the vehicle to be measured; otherwise, triggering the second steering transmission ratio measuring module;

the second steering gear ratio measuring module is used for measuring the steering gear ratio of the vehicle based on a mode of manually operating the steering wheel.

7. The device for measuring a steering gear ratio of an automobile based on ESC self-learning calibration according to claim 6, wherein the step of verifying the steering angle and inertia measurement unit by the verification module comprises:

s21, controlling the vehicle to linearly travel for a preset distance at a preset speed, keeping the speed within a preset speed allowable error for a first preset time, sending a direction angle zero point checking command by an upper computer, performing direction angle zero point checking, and acquiring a plurality of groups of direction angle values within a second preset time by an ESC after checking;

s22, if the average value of the collected multiple groups of direction angle values is in a first preset error interval, determining that the direction angle zero point verification is successful, collecting and recording multiple groups of yaw rates and lateral accelerations at the moment, carrying out low-pass filtering on the recorded yaw rates and lateral accelerations, if the average value of the filtered multiple groups of yaw rates is not in a second preset error interval or the average value of the filtered multiple groups of lateral accelerations is not in a third preset error interval, reporting that an IMU installation fault occurs, and if the average value of the filtered multiple groups of yaw rates is in the second preset error interval and the average value of the filtered multiple groups of lateral accelerations is in the third preset error interval, taking the average value of the filtered multiple groups of yaw rates at the moment as a yaw rate compensation value, taking the average value of the filtered multiple groups of lateral accelerations as a lateral acceleration compensation value, and then entering S3;

S23, if the average value of the collected multiple groups of direction angle values is not in the first preset error interval, determining that the direction angle zero point verification fails, and returning to S21 at the moment;

and S24, if the continuous three-time direction angle zero point verification fails, reporting that the fault occurs, and if the continuous three-time direction angle zero point verification is required, controlling the system to be powered on again, and returning to S21.

8. The device for measuring steering gear ratio of an automobile based on ESC self-learning calibration according to claim 7, wherein the verification module is further configured to:

after the zero point verification of the direction angle is finished, controlling the vehicle speed to rotate the steering wheel leftwards in a first preset vehicle speed interval at a speed larger than the first preset rotating speed, and recording whether the positive and negative of the longitudinal acceleration, the lateral acceleration, the direction angle and the yaw angular velocity meet a measurement coordinate system or not so as to verify the zero point verification effect of the direction angle.

9. The device for measuring a steering gear ratio of a vehicle based on ESC self-learning calibration according to claim 7, wherein the first steering gear ratio measuring module measures the steering gear ratio of the vehicle based on an active steering function of the vehicle under test, comprising:

s31, controlling the vehicle speed to be in a second preset vehicle speed interval, controlling the steering wheel to turn 90 degrees leftwards at a speed greater than a second preset rotating speed, and keeping the angle of the steering wheel unchanged for a third preset time period;

S32, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s33, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s34, the steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s35, repeating the steps S33 to S34, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s36, controlling the vehicle speed to be in a second preset vehicle speed interval, turning the steering wheel to the left by 90 degrees again at a speed greater than a second preset rotation speed, and keeping the angle of the steering wheel unchanged for a third preset time period; then repeating S32 to S35; obtaining an average value of four groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; taking an average value of the average values of the four groups of steering transmission ratios to obtain a left steering transmission ratio;

s37, controlling the vehicle speed to be in a second preset vehicle speed interval, controlling the steering wheel to turn 90 degrees rightwards at a speed greater than a second preset rotating speed, and keeping the angle of the steering wheel unchanged for a third preset time period;

S38, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s39, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s310, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s311, repeating S39 to S310, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s312, controlling the vehicle speed to be in a second preset vehicle speed interval, turning the steering wheel to the right by 90 degrees again at a speed greater than a second preset rotation speed, and keeping the steering wheel angle unchanged for a third preset time period; then repeating S38 to S311; obtaining an average value of four groups of steering transmission ratios after the steering wheel turns to the right until the angle reaches 360 degrees; and taking an average value of the average values of the four groups of steering transmission ratios to obtain the steering transmission ratio in the right direction.

10. The device for measuring the steering gear ratio of an automobile based on ESC self-learning calibration according to claim 7, wherein the second steering gear ratio measuring module is specifically configured to perform the following steps:

S41, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the left by 90 degrees in a manual steering wheel operation mode in a preset rotation error, and keeping the steering wheel angle unchanged for a fourth preset time period;

s42, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s43, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s44, calculating a steering transmission ratio I through the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s45, repeating the steps S43 to S44, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s46, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the left by 90 degrees again by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period; then repeating S42 to S45; obtaining an average value of four groups of steering transmission ratios after the steering wheel turns leftwards until the angle reaches 360 degrees; taking an average value of the average values of the four groups of steering transmission ratios to obtain a left steering transmission ratio;

S47, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the right by 90 degrees by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period;

s48, acquiring a plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle through the ESC;

s49, calculating the steering radius R by the following formula _L ：

R _L ＝R-L _y

Wherein L is _y Distance from the IMU to the centroid of the vehicle; v is the vehicle speed; omega is yaw rate; omega _offset Is a yaw rate compensation value; ay is lateral acceleration; ay _offset Is a lateral acceleration compensation value;

s410, a steering gear ratio I is calculated by the following formula:

lw is the steering angle of the steering wheel; l is the wheelbase of the vehicle;

s411, repeating S49 to S410, calculating a plurality of groups of steering transmission ratios through the collected plurality of groups of vehicle speed, yaw rate, lateral acceleration and steering wheel angle, and calculating an average value of the plurality of groups of steering transmission ratios;

s412, controlling the vehicle speed in a third preset vehicle speed interval, turning the steering wheel to the right by 90 degrees again by adopting a manual steering wheel operation mode, and keeping the steering wheel angle unchanged for a fourth preset time period; then repeating S48 to S411; obtaining an average value of four groups of steering transmission ratios after the steering wheel turns to the right until the angle reaches 360 degrees; and taking an average value of the average values of the four groups of steering transmission ratios to obtain the steering transmission ratio in the right direction.