A method and system for testing and analyzing brake deviation based on a K&C test bench.

Abstract

The application relates to a brake deviation test analysis method and system based on a K&C test bench, which comprises the following steps: performing flat jump test on a vehicle to obtain first test parameters of a measured axle of a vehicle suspension; performing longitudinal force test on the vehicle to obtain second test parameters of the measured axle of the vehicle suspension; reproducing the motion state of the suspension and the steering system in the actual braking motion process of the vehicle, performing flat jump-braking combined working condition test on the vehicle, and obtaining wheel steering angles in the flat jump-braking combined working condition test based on the vertical force-vertical displacement change coefficient of the measured axle and the longitudinal force-longitudinal displacement change coefficient of the measured axle; obtaining the vertical force contribution proportion based on the wheel steering angle, the wheel steering angle-vertical load change coefficient and the vertical force; obtaining the longitudinal force contribution proportion based on the wheel steering angle, the wheel steering angle-longitudinal load change coefficient and the longitudinal force; and comparing the vertical force contribution proportion and the longitudinal force contribution proportion to obtain the cause of the brake deviation problem of the vehicle.

Description

Technical Field

[0001] This application relates to the field of automotive suspension testing, specifically to a braking deviation test analysis method and system based on a K&C test bench. Background Technology

[0002] Braking pull is a significant issue affecting the straight-line stability of a vehicle. The main factors influencing braking pull include: Factor 1: Uneven distribution of braking force between the left and right wheels, causing vehicle pull; Factor 2: Kinematic interference between the braking and steering mechanisms, causing suspension / steering system motion interference and pull; Factor 3: Elastic deformation of the vehicle's suspension system under longitudinal forces, causing suspension / steering system motion interference and pull.

[0003] For the brake pull problem caused by factor 1, it can usually be easily identified by the wheel end brake pressure curve and the wheel speed time history, and there are already relatively mature analysis and countermeasure solutions.

[0004] Factors 2 and 3 are currently mostly used in road testing, and are not universally applicable to non-independent suspensions and rack and pinion steering systems. Furthermore, the causes of steering interference and the actual interference steering angle of the wheels cannot be directly measured. Summary of the Invention

[0005] This application provides a braking deviation test and analysis method and system based on a K&C test bench, which can solve the problem in the prior art that the cause of steering interference cannot be directly measured.

[0006] In a first aspect, embodiments of this application provide a brake pull-off test analysis method based on a K&C test bench, the brake pull-off test analysis method based on a K&C test bench includes:

[0007] A horizontal jump test is performed on the vehicle to obtain the first test parameters of the test axle of the vehicle suspension. The first test parameters include vertical force, vertical force-vertical displacement variation coefficient, and wheel steering angle-vertical load variation coefficient.

[0008] A longitudinal force test is performed on the vehicle to obtain the second test parameters of the test axle of the vehicle suspension. The second test parameters include longitudinal force, longitudinal force-longitudinal displacement variation coefficient, and wheel steering angle-longitudinal load variation coefficient.

[0009] The suspension and steering system motion states are reproduced during the actual braking process of the vehicle. The vehicle is subjected to a combined skid-brake test. Based on the vertical force-vertical displacement variation coefficient and the longitudinal force-longitudinal displacement variation coefficient of the tested axle, the wheel steering angle of the combined skid-brake test is obtained.

[0010] The contribution ratio of vertical force is obtained based on the wheel steering angle, the wheel steering angle-vertical load variation coefficient, and the vertical force.

[0011] The contribution ratio of longitudinal force is obtained based on the wheel steering angle, the wheel steering angle-longitudinal load variation coefficient, and the longitudinal force.

[0012] By comparing the contribution ratios of vertical force and longitudinal force, the causes of vehicle braking deviation can be determined.

[0013] In conjunction with the first aspect, in one implementation, the suspension and steering system motion states during the actual braking process of the vehicle are reproduced, a horizontal-bouncing-braking composite condition test is performed on the vehicle, and the wheel steering angle of the horizontal-bouncing-braking composite condition test is obtained based on the vertical force-vertical displacement variation coefficient and the longitudinal force-longitudinal displacement variation coefficient of the tested axle. Specifically, this includes:

[0014] Conduct real-vehicle road braking tests to obtain the axle load forward displacement and ground braking force under full braking conditions.

[0015] Based on the vertical force-vertical displacement variation coefficient of the tested axle, the longitudinal force-longitudinal displacement variation coefficient of the tested axle, the axle load forward displacement under full braking state of the vehicle and the ground braking force, the vertical and longitudinal travel applied to the tested axle during the composite working condition test are obtained.

[0016] The vertical travel is used as the peak value of the vertical displacement waveform, and the longitudinal travel is used as the peak value of the longitudinal displacement waveform. A composite loading motion is applied to the shaft under test to obtain the wheel steering angle under the combined test of horizontal jump and braking. The composite loading motion includes longitudinal motion and vertical motion with the same period and phase.

[0017] In conjunction with the first aspect, in one implementation, a composite loading motion is applied to the axle under test to obtain the wheel steering angle under a combined skid-brake condition test. Specific steps include:

[0018] The test shaft is subjected to longitudinal and vertical movements of the same period and phase in a cyclic manner, and the peak value of the wheel steering angle measurement corresponding to each cycle is obtained.

[0019] The average value of multiple wheel steering angle measurements is obtained, and the average value is used as the wheel steering angle under the combined test of skid-brake condition.

[0020] In conjunction with the first aspect, in one implementation, when the measured shaft performs longitudinal and vertical movements with the same period and phase, the pedal is depressed to a set position, and the steering wheel is controlled to maintain a straight position.

[0021] In conjunction with the first aspect, in one implementation, the cause of vehicle braking deviation is determined by comparing the proportions of vertical force contribution and longitudinal force contribution, specifically including:

[0022] The ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is compared with the first set threshold and the second set threshold.

[0023] If the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is greater than or equal to the first set threshold and less than or equal to the second set threshold, the causes of vehicle braking deviation include vertical motion interference of the suspension system and longitudinal deformation interference of the suspension system.

[0024] If the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is less than the first set threshold, the causes of vehicle braking deviation include vertical motion interference of the suspension system.

[0025] If the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is greater than the second set threshold, the cause of the vehicle braking deviation problem includes longitudinal deformation interference of the suspension system.

[0026] In conjunction with the first aspect, in one implementation, the first set threshold is 0.6 and the second set threshold is 1.5.

[0027] In conjunction with the first aspect, in one implementation, a level jump test is performed on the vehicle to obtain a first test parameter of the test axle of the vehicle suspension, specifically including the following steps:

[0028] A vertical load is applied to the measured shaft to the set dynamic stroke of the suspension, and the longitudinal force and lateral force of the measured shaft are synchronously canceled out.

[0029] Obtain the interference steering angle, vertical force on the measured axle, and change in the vertical position of the wheel center caused by the kinematic interference of the suspension-steering rigid body;

[0030] Based on the vertical force of the measured shaft and the change in the vertical position of the wheel center, obtain the vertical force-vertical displacement variation coefficient;

[0031] Based on the vertical force on the measured axle and the interference steering angle caused by the kinematic interference of the suspension-steering rigid body, the wheel steering angle-vertical load variation coefficient is obtained.

[0032] In conjunction with the first aspect, in one implementation, a longitudinal force test is performed on the vehicle to obtain a second test parameter of the tested axle of the vehicle suspension. Specific steps include:

[0033] A longitudinal load is applied to the measured shaft to set the braking force of the braking system, and the measured shaft is followed by lateral force and vertical force modes with the lateral force as 0 and the vertical force as the initial value.

[0034] Obtain the longitudinal force deformation steering angle, longitudinal force of the measured shaft, and longitudinal displacement of the wheel center generated by flexible deformation;

[0035] Based on the longitudinal force and longitudinal displacement of the measured shaft, obtain the longitudinal force-longitudinal displacement variation coefficient;

[0036] Based on the longitudinal force deformation steering angle generated by flexible deformation and the longitudinal force of the measured shaft, the wheel steering angle-longitudinal load variation coefficient is obtained.

[0037] In conjunction with the first aspect, in one embodiment, before performing a level jump test on the vehicle, the method further includes:

[0038] Align the wheel grounding point of the vehicle's measured axle with the center of the loading platform, and rigidly connect the wheel center sensor to the wheel center.

[0039] Install steering robot and braking actuator;

[0040] Set the various test parameters and preheat the loading platform and vehicle.

[0041] Secondly, this application provides a brake drift test and analysis system based on a K&C test bench. The system includes a loading platform, a first module, and a second module. The loading platform is used to perform horizontal jump tests and longitudinal force tests on the vehicle, replicating the suspension and steering system motion states during the actual braking process, and performing a horizontal jump-braking composite condition test on the vehicle. The first module is used to acquire first and second test parameters of the test axle of the vehicle suspension. The first test parameters include vertical force, vertical force-vertical displacement variation coefficient, and wheel steering angle-vertical load variation coefficient. The second test parameter includes longitudinal force, longitudinal force-longitudinal displacement variation coefficient, and wheel steering angle-longitudinal load variation coefficient. The second module is used to obtain the wheel steering angle of the horizontal jump-braking composite working condition test based on the vertical force-vertical displacement variation coefficient and the longitudinal force-longitudinal displacement variation coefficient of the tested axle; to obtain the vertical force contribution ratio based on the wheel steering angle, the wheel steering angle-vertical load variation coefficient, and the vertical force; and to obtain the longitudinal force contribution ratio based on the wheel steering angle, the wheel steering angle-longitudinal load variation coefficient, and the longitudinal force. By comparing the vertical force contribution ratio and the longitudinal force contribution ratio, the cause of the vehicle braking deviation problem can be obtained.

[0042] The beneficial effects of the technical solutions provided in this application include:

[0043] This application provides a braking deviation test analysis method and system based on the K&C test bench. By conducting horizontal jump tests, longitudinal force tests, and horizontal jump-braking composite condition tests on the vehicle, the braking motion state of the real vehicle is simulated in a relatively realistic way. The road test problem can be reproduced more accurately and precisely, and the contribution of factors such as system elastic deformation and motion interference to the braking deviation can be accurately analyzed. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the brake deviation test and analysis method based on the K&C test bench in this application.

[0045] Figure 2 For this application Figure 1 A detailed flowchart of step 103. Detailed Implementation

[0046] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0047] See Figures 1 to 2 This application provides a braking deviation test and analysis method and system based on the K&C test bench, which can solve the problem in the prior art that the cause of steering interference cannot be directly measured.

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0049] In a first aspect, embodiments of this application provide a brake drift test and analysis method based on a K&C test bench, comprising:

[0050] 101: Perform a horizontal jump test on the vehicle to obtain the first test parameters of the test axle of the vehicle suspension. The first test parameters include vertical force, vertical force-vertical displacement variation coefficient, and wheel steering angle-vertical load variation coefficient.

[0051] 102: Perform a longitudinal force test on the vehicle to obtain the second test parameters of the test axle of the vehicle suspension. The second test parameters include longitudinal force, longitudinal force-longitudinal displacement variation coefficient, and wheel steering angle-longitudinal load variation coefficient.

[0052] 103: Reproduce the motion state of the suspension and steering system during the actual braking process of the vehicle, conduct a horizontal jump-braking composite condition test on the vehicle, and obtain the wheel steering angle of the horizontal jump-braking composite condition test based on the vertical force-vertical displacement change coefficient and the longitudinal force-longitudinal displacement change coefficient of the tested axle.

[0053] 104: Based on the wheel steering angle, the wheel steering angle-vertical load variation coefficient, and the vertical force, obtain the contribution ratio of the vertical force;

[0054] 105: Based on the wheel steering angle, the wheel steering angle-longitudinal load variation coefficient, and the longitudinal force, obtain the longitudinal force contribution ratio;

[0055] 106: By comparing the contribution ratios of vertical force and longitudinal force, the causes of vehicle braking deviation problems can be determined.

[0056] In this application, by conducting horizontal jump tests, longitudinal force tests, and horizontal jump-braking composite condition tests on the vehicle, the braking motion state of the actual vehicle is simulated in a relatively realistic manner. The road test problems can be reproduced more accurately and precisely, thereby accurately analyzing the contribution of factors such as system elastic deformation and motion interference to the braking deviation.

[0057] It should be explained that the wheel steering angle-vertical load variation coefficient mentioned in this application describes the degree to which the wheel steering angle changes with the vertical load; the vertical force-vertical displacement variation coefficient describes the degree to which the vertical force changes with the vertical displacement; the longitudinal force-longitudinal displacement variation coefficient describes the degree to which the longitudinal force changes with the longitudinal displacement; and the wheel steering angle-longitudinal load variation coefficient describes the degree to which the wheel steering angle changes with the longitudinal load.

[0058] The skid-brake composite test refers to a test in which skid-brake and braking conditions are performed simultaneously or in combination. In the skid-brake composite test, the vehicle is tested under both skid-brake and braking conditions at the same time to simulate more complex driving scenarios.

[0059] The "tested axle" refers to the axle connected to the vehicle's suspension that needs to be tested and analyzed, which usually involves the vehicle's front or rear axle.

[0060] The vehicle's horizontal jump test, longitudinal force test, and horizontal jump-braking combined condition test in this application were conducted on a standard K&C test bench.

[0061] The K&C test bench, or automotive suspension-steering system kinematics and elasticity testing bench, is a general-purpose device for testing dynamic parameters in the automotive industry. The K&C test bench consists of four main parts: a loading platform, wheel center sensors, a steering robot, and a braking device. The loading platform can apply longitudinal, lateral, and vertical loads to the wheel contact points, and apply roll and steering angle displacements. The wheel center sensors are rigidly connected to the wheel center, directly measuring the vertical, lateral, and longitudinal three-phase translation of the wheel center, as well as the steering, roll, and roll three-dimensional angular displacements of the wheel. The steering robot is fixedly connected to the vehicle's steering wheel, accurately inputting the required steering wheel angle and angle curve, and precisely measuring the current steering wheel angle position and steering torque. The braking device directly applies force to the vehicle's brake pedal, ensuring that the maximum total force is always applied to the vehicle's braking system during the test, preventing wheel slippage under the specified load.

[0062] The loading platform of the K&C test bench can be controlled in closed loop in either force or displacement mode in the longitudinal, lateral, and vertical directions. In force mode, the loading platform can perform closed loop following motion in the corresponding direction according to the specified force or torque. In displacement mode, the loading platform can be controlled in closed loop directly according to the displacement value or displacement curve required by the instruction.

[0063] Based on the above embodiments, in this embodiment, before performing a level jump test on the vehicle, the method further includes steps 1001 to 1003:

[0064] Step 1001: Align the wheel grounding point of the vehicle's measured axle with the center of the loading platform, and rigidly connect the wheel center sensor to the wheel center.

[0065] Step 1002: Install the steering robot and braking actuator.

[0066] Step 1003: Set the various test parameters and preheat the loading platform and vehicle.

[0067] In addition, it should be noted that when conducting the experiment, the order of steps 101 and 102 can be either step 101 first and then step 102, or step 102 first and then step 101.

[0068] When performing step 101 first and then step 102, before the jump test, the vehicle must be driven onto the loading platform according to the technical requirements of the K&C equipment. The wheel ground point of the tested axle must be accurately aligned with the center of the loading platform, the wheel center sensor must be rigidly connected to the wheel center, and the steering robot and brakes must be installed and fixed as required.

[0069] Before performing step 101, in step 102, the vehicle must be driven onto the loading platform according to the technical requirements of the K&C equipment. The wheel ground point of the shaft being tested must be accurately aligned with the center of the loading platform. The wheel center sensor must be rigidly connected to the wheel center. The steering robot and brakes must be installed and fixed as required.

[0070] After the steering robot and braking actuator are installed and fixed, various test parameters are set and the equipment is preheated before conducting brake deviation analysis tests.

[0071] Based on the above embodiments, in this embodiment, a level jump test is performed on the vehicle to obtain the first test parameters of the test axle of the vehicle suspension. The specific steps include steps 1010 to 1013:

[0072] Step 1010: Apply a vertical load to the measured shaft to the suspension set travel, and make the longitudinal force and lateral force of the measured shaft cancel each other out synchronously.

[0073] Specifically, during testing, the loading platform is vertically loaded to the maximum dynamic travel of the suspension, that is, a force or load is applied to the tested shaft in the vertical direction, so that the tested shaft can reach the maximum vertical range of motion during the test. At the same time, the longitudinal and lateral forces are synchronously canceled out, that is, the longitudinal and lateral force modes are followed by the conditions Fx=0 and Fy=0, to ensure that the suspension system and steering system only generate vertical load changes during the movement.

[0074] Because the vertical and horizontal loads are completely decoupled, meaning they do not interfere with each other during operation, the vertical load can be analyzed independently. Therefore, during a vehicle's level jump test, the wheel center's three-dimensional motion curve, accurately measured by the wheel center sensor, represents the wheel center's full-stroke motion trajectory curve under the action of the suspension-steering system's guiding mechanism. The wheel angle change curve measured by the wheel center sensor represents the interference steering angle caused by the kinematic interference of the suspension-steering rigid body. The full-stroke motion trajectory curve under the action of the suspension-steering system's guiding mechanism refers to the wheel's motion trajectory relative to the frame (or body) throughout its entire range of motion under the combined action of the suspension and steering systems. The suspension-steering rigid body kinematic interference refers to the mutual interference between the suspension system and the steering system caused by structural or trajectories mismatch.

[0075] Step 1011: Obtain the interference steering angle, vertical force of the measured axle, and change in the vertical position of the wheel center caused by the kinematic interference of the suspension-steering rigid body;

[0076] Specifically, the full-stroke motion trajectory curve of the suspension-steering system guide mechanism reflects the movement of the wheel center of the tested axle in the vertical, longitudinal, and lateral directions. In the horizontal jump test, the vertical movement is taken, meaning the vertical displacement of the tested axle can be directly obtained from this trajectory curve; the vertical force on the tested axle can be obtained when a force or load is applied to the tested axle in the vertical direction.

[0077] Step 1012: Based on the vertical force of the measured shaft and the change in the vertical position of the wheel center, obtain the vertical force-vertical displacement variation coefficient.

[0078] Specifically, the vertical force-vertical displacement variation coefficient CV of the measured shaft can be obtained by measuring the vertical force Fz and vertical displacement z, where CV = Fz / z.

[0079] Step 1013: Based on the vertical force of the measured axle and the interference steering angle caused by the kinematic interference of the suspension-steering rigid body, obtain the wheel steering angle-vertical load variation coefficient.

[0080] Specifically, the wheel steering angle-vertical load variation coefficient εV can be obtained by using the vertical force Fz of the measured shaft and the interference steering angle sa1 caused by the kinematic interference of the suspension-steering rigid body, where εV = sa1 / Fz.

[0081] Based on the above embodiments, in this embodiment, a longitudinal force test is performed on the vehicle to obtain the second test parameter of the test axle of the vehicle suspension. The specific steps include steps 1020 to 1023:

[0082] Step 1020: Apply a longitudinal load to the brake system to set the braking force, and perform follow-up motion of the lateral force and vertical force modes of the measured shaft with the lateral force as 0 and the vertical force as the initial value.

[0083] Specifically, when conducting longitudinal force tests on a vehicle, a loading platform is used to apply a longitudinal load to the tested axle up to the maximum braking force of the braking system. This involves gradually increasing the longitudinal load on the tested axle using the loading platform to simulate the braking conditions of the vehicle under different weights. During the loading process, the loading platform operates in force mode, with Fy = 0 and Fz = initial values, performing lateral and vertical force follow-up. This achieves complete decoupling of the longitudinal force loading from loads in other directions, meaning that the longitudinal load and loads in other directions do not interfere with each other during operation, allowing for independent analysis of the longitudinal load.

[0084] The three-dimensional motion curve of the wheel center measured by the wheel center sensor during the longitudinal force test of the vehicle is the flexible deformation curve of the suspension system under the action of a single longitudinal force.

[0085] Step 1021: Obtain the longitudinal force deformation steering angle, longitudinal force of the measured shaft, and longitudinal displacement of the wheel center generated by the flexible deformation.

[0086] Specifically, the longitudinal displacement of the wheel center of the shaft under test can be directly obtained by the flexible deformation curve of the suspension system under a single longitudinal force; the longitudinal force on the shaft under test can also be obtained when a force or load is applied to the shaft under test in the longitudinal direction.

[0087] The wheel angle change curve directly measured by the wheel center sensor is the longitudinal force deformation steering angle generated by flexible deformation.

[0088] Step 1022: Based on the longitudinal force and longitudinal displacement of the measured shaft, obtain the longitudinal force-longitudinal displacement variation coefficient.

[0089] Specifically, the longitudinal force-longitudinal displacement variation coefficient CL of the measured shaft can be obtained by using the longitudinal force Fx and longitudinal displacement X of the measured shaft, where CL = Fx / X.

[0090] Step 1023: Based on the longitudinal force deformation steering angle generated by flexible deformation and the longitudinal force of the measured shaft, obtain the wheel steering angle-longitudinal load variation coefficient.

[0091] Specifically, by using the longitudinal force deformation steering angle sa2 generated by flexible deformation and the longitudinal force Fx of the measured shaft, the wheel steering angle-longitudinal load variation coefficient εL can be obtained, εL=sa2 / Fx.

[0092] Based on the above embodiments, in this embodiment, the suspension and steering system motion states during the actual braking process of the vehicle are reproduced, a horizontal jump-braking composite condition test is performed on the vehicle, and the wheel steering angle of the horizontal jump-braking composite condition test is obtained based on the vertical force-vertical displacement change coefficient and the longitudinal force-longitudinal displacement change coefficient of the tested axle. Specifically, steps 1030 to 1032 are included.

[0093] Among them, conducting a horizontal jump-braking combined test on the vehicle can obtain the longitudinal and vertical synchronous loading boundary conditions under the horizontal jump-braking combined test, and then measure the wheel steering angle under the combined test.

[0094] It should be noted that the actual braking process of a vehicle involves the generation of longitudinal braking force between the wheels and the ground, resulting in vehicle braking deceleration, forward center of gravity shift due to inertia, and synchronous compression of the suspension system. Therefore, the braking process is actually accompanied by a combined loading motion of longitudinal force and suspension bounce. Thus, by testing under combined working conditions, the braking process of the vehicle during actual road driving can be accurately reproduced. This allows for a more accurate analysis of the contribution of factors such as system elastic deformation and motion interference to braking deviation, guiding design improvements.

[0095] Step 1030: Conduct a real-vehicle road braking test on the vehicle to obtain the axle load forward displacement and ground braking force under full braking conditions.

[0096] Specifically, real-world road braking tests are conducted on the vehicle, and the axle load forward displacement F under full braking conditions is obtained using sensors and force measuring equipment. T and ground braking force F B .

[0097] In addition, the axle load forward displacement F under full braking conditions can be calculated theoretically. T and ground braking force F B In theoretical calculations, the axle load forward displacement F under full braking conditions is calculated using mechanical formulas based on parameters such as vehicle center of gravity height, vehicle mass, and braking deceleration. T Based on parameters such as vehicle weight, tire-ground adhesion coefficient, and braking system efficiency, the ground braking force F under full braking conditions is calculated using mechanical formulas. B .

[0098] In this application, the axle load forward displacement FT is the vertical load increment of the tested axle under the combined conditions of horizontal jump and braking, and the ground braking force F is... B This refers to the longitudinal load that needs to be applied to the shaft under test during the combined conditions of horizontal jump and braking.

[0099] Step 1031: Based on the vertical force-vertical displacement variation coefficient of the tested axle, the longitudinal force-longitudinal displacement variation coefficient of the tested axle, the axle load forward displacement under full braking state of the vehicle and the ground braking force, obtain the vertical and longitudinal travel applied to the tested axle during the composite working condition test.

[0100] Specifically, the vertical force-vertical displacement variation coefficient C of the measured shaft is used. V The coefficient of variation C of longitudinal force-longitudinal displacement of the measured shaft L Axle load forward displacement F under full braking condition of vehicle T and ground braking force F B The vertical travel SV and longitudinal travel SL required for the vehicle to undergo a horizontal jump-braking combined test are calculated respectively.

[0101] SV = F T / C V

[0102] SL=F B / C L

[0103] Step 1032: Using the vertical travel as the peak value of the vertical displacement waveform and the longitudinal travel as the peak value of the longitudinal displacement waveform, apply a composite loading motion to the shaft under test to obtain the wheel steering angle under the combined test of horizontal jump and braking. The composite loading motion includes longitudinal and vertical motions with the same period and phase.

[0104] Specifically, through displacement control mode, the loading platform is made to perform longitudinal and vertical movements with the same period and phase using triangular or sine wave waveforms. The peak values ​​of the displacement waveforms are the vertical travel SV and longitudinal travel SL required for the vehicle to undergo a horizontal jump-braking combined load test, calculated in step 1031. It is important to note that the phase and period of the vertical and longitudinal movement waveforms must be controlled to ensure that the loads in both directions reach the target values ​​synchronously.

[0105] The test involves applying a composite loading motion to the tested axle to obtain the wheel steering angle under a combined skid-brake condition test. Specific steps include: cyclically performing longitudinal and vertical movements of the tested axle with the same period and phase, and obtaining the peak wheel steering angle measurement for each cycle; then, obtaining the average value of the peak wheel steering angle measurements from multiple cycles, and using this average value as the wheel steering angle Sa under the combined skid-brake condition test. The wheel steering angle Sa recorded during this composite loading motion allows for a direct assessment of the vehicle's braking deviation direction and steering deflection.

[0106] Simultaneously, when the measured shaft performs longitudinal and vertical movements with the same period and phase, the brake pedal is depressed to a set position, and the steering wheel is controlled to maintain a straight-line position. In this embodiment, the set position refers to the position when the brake pedal is fully depressed.

[0107] Based on the above embodiments, in this embodiment, the vertical force contribution ratio K2 is obtained based on the wheel steering angle Sa, the wheel steering angle-vertical load variation coefficient εV, and the vertical force Fz. The vertical force contribution ratio K2 = εV / (Sa / Fz).

[0108] Based on the above embodiments, in this embodiment, the longitudinal force contribution ratio K1 is obtained based on the wheel steering angle Sa, the wheel steering angle-longitudinal load variation coefficient εL, and the longitudinal force Fx, where the longitudinal force contribution ratio K1 = εL / (Sa / Fx).

[0109] Based on the above embodiments, in this embodiment, the cause of vehicle braking deviation is obtained by comparing the vertical force contribution ratio and the longitudinal force contribution ratio, specifically including steps 1060 to 1061:

[0110] Step 1060: Compare the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio with the first set threshold and the second set threshold;

[0111] Step 1061: If the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is greater than or equal to the first set threshold and less than or equal to the second set threshold, the causes of vehicle braking pull-off include vertical motion interference of the suspension system and longitudinal deformation interference of the suspension system; if the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is less than the first set threshold, the causes of vehicle braking pull-off include vertical motion interference of the suspension system; if the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is greater than the second set threshold, the causes of vehicle braking pull-off include longitudinal deformation interference of the suspension system.

[0112] Specifically, by comparing the values ​​of K1 and K2, we can more accurately guide the main causes of the brake pull problem in the tested vehicle and identify key areas for improvement.

[0113] The first set threshold is 0.6, and the second set threshold is 1.5.

[0114] If K1 / K2 > 1.5, then the brake pull is mainly caused by longitudinal deformation interference of the suspension system. The key improvement direction for the brake pull problem is to reduce the longitudinal torsional deformation of the suspension-steering system.

[0115] If K1 / K2 < 0.6, then the brake pull is mainly caused by vertical motion interference of the suspension system. The key to improving the brake pull problem is to optimize the mechanism layout and reduce the amount of steering interference caused by suspension bounce.

[0116] If 0.6≤K1 / K2≤1.5, then both the horizontal bouncing interference and the longitudinal torsional deformation interference of the suspension-steering system need to be modified and tested. The main directions for improvement are: 1. Optimize and reduce the amount of interference of both types of deformation; 2. If the longitudinal torsional deformation interference cannot be optimized, then focus on optimizing the mechanism layout so that the upward bouncing direction of the suspension-steering system is opposite to the longitudinal torsional deformation interference direction.

[0117] In summary, this application uses a K&C test bench commonly used in the automotive industry and implements the above process by editing specific test cases. It does not cause significant damage to the vehicle under test and does not produce special tooling fixtures or special measuring devices.

[0118] By calculating the force-displacement curves in the longitudinal and vertical directions, the synchronous loading of vertical and longitudinal forces is achieved through displacement control. The control method is simple and the test results are highly repeatable.

[0119] It uses general-purpose K&C testing equipment, and the testing methods are applicable to both independent and non-independent suspensions.

[0120] The flat-jump-brake composite test realistically simulates the braking motion of a real vehicle, can accurately reproduce road test problems, and can be used as a standard test method to verify the effect of vehicle deviation improvement and to judge the deviation quality standard.

[0121] Secondly, this application provides a brake drift test and analysis system based on a K&C test bench, comprising: a loading platform, a first module, and a second module. The loading platform is used to perform horizontal jump tests and longitudinal force tests on a vehicle, reproducing the suspension and steering system motion states during the actual braking process of the vehicle, and performing a horizontal jump-braking composite condition test on the vehicle. The first module is used to acquire first test parameters and second test parameters of the test axle of the vehicle suspension. The first test parameters include vertical force, vertical force-vertical displacement variation coefficient, and wheel steering angle-vertical load variation coefficient. The second test parameters... The first module includes longitudinal force, longitudinal force-longitudinal displacement variation coefficient, and wheel steering angle-longitudinal load variation coefficient. The second module is used to obtain the wheel steering angle of the horizontal jump-braking composite test based on the vertical force-vertical displacement variation coefficient and the longitudinal force-longitudinal displacement variation coefficient of the tested shaft. Based on the wheel steering angle, wheel steering angle-vertical load variation coefficient, and vertical force, the vertical force contribution ratio is obtained. Based on the wheel steering angle, wheel steering angle-longitudinal load variation coefficient, and longitudinal force, the longitudinal force contribution ratio is obtained. By comparing the vertical force contribution ratio and the longitudinal force contribution ratio, the cause of the vehicle braking deviation problem is obtained.

[0122] In this application, by conducting horizontal jump tests, longitudinal force tests, and horizontal jump-braking composite condition tests on the vehicle, the braking motion state of the actual vehicle is simulated in a relatively realistic manner. The road test problems can be reproduced more accurately and precisely, thereby accurately analyzing the contribution of factors such as system elastic deformation and motion interference to the braking deviation.

[0123] Thirdly, this application provides a brake pull test and analysis device based on a K&C test bench. The brake pull test and analysis device based on a K&C test bench can be a personal computer (PC), laptop computer, server or other device with data processing capabilities.

[0124] In this embodiment of the application, the brake deviation test and analysis device based on the K&C test bench may include a processor, a memory, a communication interface, and a communication bus.

[0125] The communication bus can be of any type and is used to interconnect the processor, memory, and communication interface.

[0126] The communication interface includes input / output (I / O) interfaces, physical interfaces, and logical interfaces. These interfaces enable interconnection of internal components within the brake pullback testing and analysis equipment based on the K&C test bench, and also enable interconnection between the equipment and other devices (such as other computing devices or user equipment). Physical interfaces can be Ethernet interfaces, fiber optic interfaces, ATM interfaces, etc.; user equipment can be displays, keyboards, etc.

[0127] Memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0128] The processor can be a general-purpose processor, which can call the brake pull test analysis program based on the K&C test bench stored in the memory and execute the brake pull test analysis method based on the K&C test bench provided in the embodiments of this application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the brake pull test analysis program based on the K&C test bench is called can refer to the various embodiments of the brake pull test analysis method based on the K&C test bench of this application, and will not be repeated here.

[0129] Fourthly, embodiments of this application also provide a computer-readable storage medium.

[0130] The present application stores a brake drift test analysis program based on a K&C test bench on a computer-readable storage medium, wherein when the brake drift test analysis program based on a K&C test bench is executed by a processor, the steps of the brake drift test analysis method based on a K&C test bench as described above are implemented.

[0131] The method implemented when the brake pull test analysis program based on the K&C test bench is executed can be referred to in the various embodiments of the brake pull test analysis method based on the K&C test bench of this application, and will not be repeated here.

[0132] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0133] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0134] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0135] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0136] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0137] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0138] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for testing and analyzing brake deviation based on a K&C test bench, characterized in that, The braking deviation test and analysis method based on the K&C test bench includes: A horizontal jump test is performed on the vehicle to obtain the first test parameters of the test axle of the vehicle suspension. The first test parameters include vertical force, vertical force-vertical displacement variation coefficient, and wheel steering angle-vertical force variation coefficient. A longitudinal force test is performed on the vehicle to obtain the second test parameters of the test axle of the vehicle suspension. The second test parameters include longitudinal force, longitudinal force-longitudinal displacement variation coefficient, and wheel steering angle-longitudinal force variation coefficient. The suspension and steering system motion states are reproduced during the actual braking process of the vehicle. The vehicle is subjected to a combined skid-brake test. Based on the vertical force-vertical displacement variation coefficient and the longitudinal force-longitudinal displacement variation coefficient of the tested axle, the wheel steering angle of the combined skid-brake test is obtained. Based on the wheel steering angle, the wheel steering angle-vertical force variation coefficient, and the vertical force, the contribution ratio of the vertical force is obtained; Based on the wheel steering angle, the wheel steering angle-longitudinal force variation coefficient, and the longitudinal force, the contribution ratio of the longitudinal force is obtained; By comparing the contribution ratios of vertical force and longitudinal force, the causes of vehicle braking deviation can be determined. The suspension and steering system motion states are reproduced during the actual braking process of the vehicle. A combined skid-bounce and braking test is performed on the vehicle. Based on the vertical force-vertical displacement variation coefficient and the longitudinal force-longitudinal displacement variation coefficient of the tested axle, the wheel steering angles during the combined skid-bounce and braking test are obtained. Specifically, this includes: Conduct real-vehicle road braking tests to obtain the axle load forward displacement and ground braking force under full braking conditions. Based on the vertical force-vertical displacement variation coefficient of the tested axle, the longitudinal force-longitudinal displacement variation coefficient of the tested axle, the axle load forward displacement under full braking state of the vehicle and the ground braking force, the vertical and longitudinal travel applied to the tested axle during the composite working condition test are obtained. The vertical travel is used as the peak value of the vertical displacement waveform, and the longitudinal travel is used as the peak value of the longitudinal displacement waveform. A composite loading motion is applied to the shaft under test to obtain the wheel steering angle under the combined test of horizontal jump-braking. The composite loading motion includes longitudinal motion and vertical motion with the same period and phase. The wheel steering angle under the combined loading motion of the tested axle is obtained by obtaining the wheel steering angle under the combined loading and braking conditions. The specific steps include: The test shaft is subjected to longitudinal and vertical movements of the same period and phase in a cyclic manner, and the peak value of the wheel steering angle measurement corresponding to each cycle is obtained. The average value of multiple wheel steering angle measurements is obtained, and the average value is used as the wheel steering angle under the combined test of skid-brake condition.

2. The braking deviation test and analysis method based on the K&C test bench as described in claim 1, characterized in that, When the measured axis performs longitudinal and vertical movements with the same period and phase, press the pedal to the set position and control the steering wheel to keep it in a straight position.

3. The braking deviation test and analysis method based on the K&C test bench as described in claim 1, characterized in that, By comparing the proportions of vertical force contribution and longitudinal force contribution, the causes of vehicle braking pull-off problems can be identified, including: The ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is compared with the first set threshold and the second set threshold. If the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is greater than or equal to the first set threshold and less than or equal to the second set threshold, the causes of vehicle braking deviation include vertical motion interference of the suspension system and longitudinal deformation interference of the suspension system. If the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is less than the first set threshold, the causes of vehicle braking deviation include vertical motion interference of the suspension system. If the ratio of the vertical force contribution ratio to the longitudinal force contribution ratio is greater than the second set threshold, the cause of the vehicle braking deviation problem includes longitudinal deformation interference of the suspension system.

4. The braking deviation test and analysis method based on the K&C test bench as described in claim 3, characterized in that: The first set threshold is 0.6, and the second set threshold is 1.

5.

5. The braking deviation test and analysis method based on the K&C test bench as described in claim 1, characterized in that, Perform a level jump test on the vehicle to obtain the first test parameters of the test axle of the vehicle suspension. The specific steps include: A vertical force is applied to the measured shaft to the set travel of the suspension, and the longitudinal and lateral forces of the measured shaft are synchronously canceled out. Obtain the interference steering angle, vertical force on the measured axle, and change in the vertical position of the wheel center caused by the kinematic interference of the suspension-steering rigid body; Based on the vertical force of the measured shaft and the change in the vertical position of the wheel center, obtain the vertical force-vertical displacement variation coefficient; Based on the vertical force of the measured axle and the interference steering angle caused by the kinematic interference of the suspension-steering rigid body, the wheel steering angle-vertical force variation coefficient is obtained.

6. The braking deviation test and analysis method based on the K&C test bench as described in claim 1, characterized in that, A longitudinal force test is performed on the vehicle to obtain the second test parameter of the test axle of the vehicle suspension. The specific steps include: A longitudinal force is applied to the measured shaft to set the braking force of the braking system, and the measured shaft is followed by lateral force and vertical force modes with the lateral force as 0 and the vertical force as the initial value. Obtain the longitudinal force deformation steering angle, longitudinal force of the measured shaft, and longitudinal displacement of the wheel center generated by flexible deformation; Based on the longitudinal force and longitudinal displacement of the measured shaft, obtain the longitudinal force-longitudinal displacement variation coefficient; Based on the longitudinal force deformation steering angle generated by flexible deformation and the longitudinal force of the measured shaft, the wheel steering angle-longitudinal force variation coefficient is obtained.

7. The braking deviation test and analysis method based on the K&C test bench as described in claim 1, characterized in that, Before performing a level jump test on the vehicle, the method further includes: Align the wheel grounding point of the vehicle's measured axle with the center of the loading platform, and rigidly connect the wheel center sensor to the wheel center. Install a steering robot and brakes; Set the various test parameters and preheat the loading platform and vehicle.

8. A brake deviation test and analysis system based on a K&C test bench, characterized in that, The brake pull-off test and analysis system based on the K&C test bench includes: The loading platform is used to perform horizontal jump tests and longitudinal force tests on the vehicle, reproduce the suspension and steering system motion states during the actual braking process of the vehicle, and perform horizontal jump-braking composite condition tests on the vehicle. The first module is used to acquire the first test parameters and the second test parameters of the test shaft of the vehicle suspension. The first test parameters include vertical force, vertical force-vertical displacement variation coefficient, and wheel steering angle-vertical force variation coefficient. The second test parameters include longitudinal force, longitudinal force-longitudinal displacement variation coefficient, and wheel steering angle-longitudinal force variation coefficient. The second module is used to obtain the wheel steering angle of the horizontal jump-braking composite working condition test based on the vertical force-vertical displacement change coefficient and the longitudinal force-longitudinal displacement change coefficient of the tested shaft; to obtain the vertical force contribution ratio based on the wheel steering angle, the wheel steering angle-vertical force change coefficient and the vertical force; to obtain the longitudinal force contribution ratio based on the wheel steering angle, the wheel steering angle-longitudinal force change coefficient and the longitudinal force; and to obtain the cause of the vehicle braking deviation problem by comparing the vertical force contribution ratio and the longitudinal force contribution ratio. The second module also includes: Obtain the axle load forward displacement and ground braking force under full braking conditions of the vehicle obtained from real-vehicle road braking tests. Based on the vertical force-vertical displacement variation coefficient of the tested axle, the longitudinal force-longitudinal displacement variation coefficient of the tested axle, the axle load forward displacement under full braking state of the vehicle and the ground braking force, the vertical and longitudinal travel applied to the tested axle during the composite working condition test are obtained. The vertical stroke is used as the peak value of the vertical displacement waveform, and the longitudinal stroke is used as the peak value of the longitudinal displacement waveform. The loading platform is controlled to perform a compound loading motion on the shaft under test to obtain the wheel steering angle under the combined test of horizontal jump and braking. The compound loading motion includes longitudinal motion and vertical motion with the same period and phase. Specifically, controlling the loading platform to perform a compound loading motion on the tested axle to obtain the wheel steering angle under the combined test conditions of horizontal jump and braking includes: The test shaft is subjected to longitudinal and vertical movements of the same period and phase in a cyclic manner, and the peak value of the wheel steering angle measurement corresponding to each cycle is obtained. The average value of multiple wheel steering angle measurements is obtained, and the average value is used as the wheel steering angle under the combined test of skid-brake condition.

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