Vehicle brake pedal characteristic calibration method and device

Abstract

The invention provides a vehicle brake pedal characteristic calibration method and device, and the method comprises the steps: carrying out the slow braking test of a test vehicle under a preset test condition, obtaining a plurality of groups of first brake test data, and carrying out the following processing for each group of first brake test data: employing the collected deceleration as an abscissa array, performing first-order linear interpolation on the longitudinal coordinate array by taking the pressure of the servo cylinder as the longitudinal coordinate array to obtain a first interpolation function; performing first-order linear interpolation by taking the acquired pedal travel as an abscissa array and the brake master cylinder push rod travel as an ordinate array to obtain a second interpolation function; and according to the target deceleration number array, each group of first interpolation functions, the target pedal travel data and each group of second interpolation functions, determining brake calibration parameters, and completing calibration. According to the method, the pedal characteristics of the test vehicle are accurately adjusted and optimized according to the target deceleration data through the first-order linear interpolation method, and the calibration precision of the vehicle braking parameters is improved.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle brake pedal characteristic calibration, and in particular to a vehicle brake pedal characteristic calibration method and device. Background Art

[0002] At present, the technology of brake pedal characteristic calibration mainly involves how to realize the adjustable function of pedal characteristics from the hardware structure of integrated brake control system and how to test the brake pedal characteristics on a real vehicle or test bench. There are very few calibration methods for brake pedal characteristics.

[0003] According to the pedal characteristic calibration input requirements of the integrated brake control system and the limited data sampling rate during the test data acquisition process, the actual measured results are discrete signals, and the influence of random errors cannot be eliminated, resulting in unsatisfactory final calibration results. Summary of the invention

[0004] In view of this, the purpose of the present application is to at least provide a vehicle brake pedal characteristic calibration method and device, which uses a first-order linear interpolation method to accurately adjust the pedal characteristics of the test vehicle according to the target deceleration data, thereby improving the calibration accuracy of the vehicle brake parameters.

[0005] This application mainly includes the following aspects:

[0006] In a first aspect, an embodiment of the present application provides a vehicle brake pedal characteristic calibration method, the method comprising: performing a slow braking test on a test vehicle under preset test conditions, collecting multiple sets of first braking test data through a preset data acquisition system, each set of first braking test data including time history data of deceleration, pedal travel, pedal force, servo cylinder pressure and brake master cylinder push rod travel during braking; determining the availability of a pedal simulator based on the multiple sets of first braking test data and a preset pedal characteristic curve; if it is determined that the pedal simulator is available, performing the following processing for each set of first braking test data: using the collected The first interpolation function is obtained by performing first-order linear interpolation with the deceleration as the horizontal coordinate array and the servo cylinder pressure as the vertical coordinate array; the second interpolation function is obtained by performing first-order linear interpolation with the collected pedal stroke as the horizontal coordinate array and the brake master cylinder push rod stroke as the vertical coordinate array; the brake calibration parameters are determined according to the target deceleration array, the first interpolation function corresponding to each group of first brake test data, the target pedal stroke data and the second interpolation function corresponding to each group of first brake test data; the brake calibration parameters are written into the control software of the integrated brake control system to complete the calibration of the brake pedal characteristics of the test vehicle.

[0007] In one possible implementation, the pedal characteristic curve is determined in the following manner: a target deceleration array corresponding to the test vehicle is defined, the target deceleration array includes multiple target decelerations; a target pedal force array and a target pedal stroke array corresponding to the target deceleration array are determined, the target pedal force array includes a target pedal force corresponding to each target deceleration, and the target pedal stroke array includes a target pedal stroke corresponding to each target deceleration; a pedal force upper limit array and a pedal force lower limit array corresponding to the target pedal force array, and a pedal stroke upper limit array and a pedal stroke lower limit array corresponding to the target pedal stroke array are calculated according to preset accuracy requirements, the pedal force upper limit array includes a pedal force upper limit corresponding to each target pedal force, the pedal force lower limit array includes a pedal force lower limit corresponding to each target pedal force, the pedal stroke upper limit array includes a pedal stroke upper limit corresponding to each target pedal stroke, and the pedal stroke lower limit array includes a pedal stroke lower limit corresponding to each target pedal stroke; and a pedal characteristic curve is drawn according to the target deceleration array, the target pedal force array, the target pedal stroke array, the pedal force upper limit array, the pedal force lower limit array, and the pedal stroke upper limit array and the pedal stroke lower limit array.

[0008] In one possible implementation, the pedal characteristic curve includes a first pedal characteristic curve, a second pedal characteristic curve and a third pedal characteristic curve, wherein the pedal characteristic curve is drawn in the following manner: using the target deceleration array as the ordinate array, and using the pedal force upper limit array, the target pedal force array and the pedal force lower limit array as the abscissa array, performing cubic spline interpolation in the first preset coordinate system to generate the corresponding first pedal force braking curve, the second pedal force braking curve and the third pedal force braking curve; using the target deceleration array as the ordinate array, and using the target pedal travel upper limit array, the pedal travel array and the pedal travel lower limit array as the abscissa array, and ... As the horizontal coordinate array, cubic spline interpolation is performed in the second preset coordinate system to generate the corresponding first pedal stroke braking curve, second pedal stroke braking curve and third pedal stroke braking curve; with the pedal force upper limit array as the horizontal coordinate array and the pedal stroke lower limit array as the vertical coordinate data, the pedal force lower limit array as the horizontal coordinate array and the pedal stroke upper limit array as the vertical coordinate data, the target pedal force array as the horizontal coordinate array and the target pedal stroke array as the vertical coordinate data, cubic spline interpolation is performed in the third preset coordinate system to form the corresponding first pedal characteristic curve, second pedal characteristic curve and third pedal characteristic curve in the third preset coordinate system.

[0009] In one possible implementation, the slow braking test includes: performing brake preheating driving on the test vehicle; performing multiple braking tests on the test vehicle after the brake preheating driving in opposite directions between the starting point and the destination; for each braking test, performing the following processing: controlling the test vehicle to accelerate to a first preset speed, with the transmission gear at a target gear, the target gear being the highest gear that enables the test vehicle to stably maintain the first preset speed, releasing the accelerator pedal and maintaining the target gear unchanged, and controlling the test vehicle to start braking when the vehicle speed drops to a second preset speed; during the braking process, performing the following processing: controlling the brake pedal stroke to increase by less than or equal to a preset increment until the anti-lock braking system starts to work or the wheels of the test vehicle lock, maintaining the target gear unchanged, and disengaging the clutch before the test vehicle stops; and obtaining the first braking test data generated during each braking test through the target.

[0010] In one possible implementation, the availability of the pedal simulator is determined in the following manner: the area between the first pedal characteristic curve and the vertical axis of the third preset coordinate system is defined as the first area, the area between the first pedal characteristic curve and the third pedal characteristic curve is defined as the second area, and the area between the third pedal characteristic curve and the horizontal axis of the third preset coordinate system is defined as the third area; for each group of first braking test data, first-order linear interpolation is performed with the collected pedal force as the horizontal coordinate array and the pedal stroke as the vertical coordinate array, and the corresponding test pedal characteristic curve is drawn in the third coordinate system; if the test pedal characteristic curve corresponding to each group of first braking test data is located in the second area, it is determined that the pedal simulator is available; if there is any group of first braking test data The corresponding test pedal characteristic curve is located in the first area or the third area, it is determined that the pedal simulator is unavailable.

[0011] In one possible implementation, the brake calibration parameters include an average target pressure array and an average target master cylinder push rod stroke array, wherein the brake calibration parameters are determined in the following manner: for each group of first brake test data, the following processing is performed: the collected deceleration is filtered using the Savitzky-Golay filtering algorithm; first-order linear interpolation is performed using the filtered deceleration as the horizontal coordinate array and the servo cylinder pressure as the vertical coordinate array to obtain a first interpolation function; the target pedal stroke array is substituted into the first interpolation function as an independent variable to obtain a target pressure array; first-order linear interpolation is performed using the collected pedal stroke as the horizontal coordinate array and the brake master cylinder push rod stroke as the vertical coordinate array to obtain a second interpolation function; the target pedal stroke array is substituted into the second interpolation function as an independent variable to obtain a corresponding push rod stroke array; the average of the bitwise elements of the target pressure array corresponding to each group of first brake test data is calculated to obtain an average target pressure array; the average of the bitwise elements of the push rod stroke array of each group of first brake test data is calculated to obtain an average target master cylinder push rod stroke array.

[0012] In one possible implementation, after the brake calibration parameters are written into the control software of the integrated brake control system, the method further includes: re-performing a slow braking test on the test vehicle, and collecting multiple sets of second brake test data through a preset data acquisition system; for each set of second brake test data, performing first-order linear interpolation with the collected deceleration as the horizontal coordinate array and the pedal stroke as the vertical coordinate array to obtain a third interpolation function; bringing the target deceleration array as an independent variable into the third interpolation function corresponding to each set of second brake test data, and obtaining an actual pedal stroke array corresponding to each set of second brake test data; averaging each corresponding element in the multiple actual pedal stroke arrays to obtain a target actual pedal stroke array; determining the target Whether each element in the actual pedal stroke array satisfies the corresponding pedal stroke upper limit and pedal stroke lower limit; if each element in the target actual pedal stroke array satisfies the corresponding pedal stroke upper limit and pedal stroke lower limit, the calibration is determined to be successful, and the average target master cylinder push rod stroke array and the average target pressure array are determined as brake pedal characteristic calibration parameters to complete the calibration; if any element in the target actual pedal stroke array does not satisfy the corresponding pedal stroke upper limit and pedal stroke lower limit, the calibration is determined to have failed, and parameter correction processing is performed on the average target pressure array, and the corrected average target pressure array and average target master cylinder push rod stroke array are re-written into the control software of the integrated brake control system until the calibration is successful.

[0013] In one possible implementation, the parameter correction processing includes: for each group of second braking test data, first-order linear interpolation is performed with the pedal stroke as the horizontal coordinate array and the deceleration as the vertical coordinate array to obtain a fourth interpolation function; each element in the target pedal stroke array is substituted into the fourth interpolation function as an independent variable in turn to obtain the corresponding actual deceleration array; the average value of each corresponding element in the actual deceleration array corresponding to each group of second braking test data is calculated to obtain a target actual deceleration array; for each element in the target actual deceleration array and the target deceleration array, the corresponding deviation coefficient is calculated to form a deviation array, wherein the deviation coefficient = (target deceleration - actual deceleration) / target deceleration; each element in the average target pressure array is corrected through the deviation array to obtain a corrected average target pressure array, wherein each element in the corrected average target pressure array = the average target pressure corresponding to the element × (1 + the deviation coefficient corresponding to the element).

[0014] In one possible implementation, the brake preheating driving of the test vehicle is performed in the following manner: a preset brake preheating data table is obtained, the preset brake preheating data table includes a brake preheating initial speed, a brake preheating final speed, a preheating average deceleration, a braking operation, a braking interval and a number of preheating brakes; the test vehicle is controlled to travel at a constant speed according to the brake preheating initial speed; the test vehicle is controlled to perform multiple braking stops according to the braking interval and the number of preheating brakes, so that the brake temperature of the test vehicle reaches a preset operating temperature, and the preset operating temperature is between 70°C and 100°C.

[0015] In one possible implementation, the method also includes: before performing a slow braking test on the test vehicle, controlling the test vehicle to perform brake running-in driving according to a preset brake running-in data table, the preset brake running-in data table including the running-in braking initial speed, the running-in braking final speed, the running-in average deceleration, the braking operation and the number of running-in brakes, the braking operation being sudden braking; for each brake running-in driving, performing the following processing: the brake temperature before braking is less than or equal to 150°C, after braking, the test vehicle accelerates to the running-in braking initial speed within a preset time and maintains a constant speed, the brake temperature is less than or equal to 150°C, and the next braking is performed; during the braking period, the transmission is placed in N gear; after the brake is run-in according to the number of running-in brakes, checking the contact state of the brake friction element, and when the contact state of the brake friction element meets the design requirements, performing a slow braking test on the test vehicle in a preset test environment.

[0016] In one possible implementation, the preset test conditions include: the test road surface is a dry, flat asphalt or concrete paved road; the slope of the test road over any 50-meter longitudinal length is less than 1%, the road crown slope is less than 2%, the maximum wind speed in the test environment is less than 5m / s, the average wind speed is less than or equal to 3m / s, and the atmospheric temperature is 0°C to 35°C; the test mass is the curb mass corresponding to the test vehicle plus a 180kg test load; the cold inflation pressure of the test vehicle tires meets the preset manufacturing technical requirements.

[0017] In a second aspect, the embodiment of the present application further provides a vehicle brake pedal characteristic calibration device, the device comprising: a braking test module, used to perform a slow braking test on a test vehicle under preset test conditions, and collect multiple groups of first braking test data through a preset data acquisition system, each group of first braking test data includes deceleration, pedal travel, pedal force, servo cylinder pressure and time history data of the brake master cylinder push rod travel during braking; an availability test module, used to determine the availability of a pedal simulator based on multiple groups of first braking test data and a preset pedal characteristic curve; an interpolation module, used to perform the following processing for each group of first braking test data if it is determined that the pedal simulator is available: collect The collected deceleration is used as the horizontal coordinate array, and the servo cylinder pressure is used as the vertical coordinate array for first-order linear interpolation to obtain the first interpolation function, and the collected pedal stroke is used as the horizontal coordinate array, and the brake master cylinder push rod stroke is used as the vertical coordinate array for first-order linear interpolation to obtain the second interpolation function; a brake calibration parameter determination module is used to determine the brake calibration parameters according to the target deceleration array, the first interpolation function corresponding to each group of first brake test data, the target pedal stroke data and the second interpolation function corresponding to each group of first brake test data; a calibration module is used to write the brake calibration parameters into the control software of the integrated brake control system to complete the calibration of the brake pedal characteristics of the test vehicle.

[0018] The embodiment of the present application provides a vehicle brake pedal characteristic calibration method and device, including: performing a slow braking test on a test vehicle under preset test conditions to obtain multiple groups of first brake test data, and performing the following processing for each group of first brake test data: performing first-order linear interpolation with the collected deceleration as the horizontal coordinate array and the servo cylinder pressure as the vertical coordinate array to obtain a first interpolation function; performing first-order linear interpolation with the collected pedal stroke as the horizontal coordinate array and the brake master cylinder push rod stroke as the vertical coordinate array to obtain a second interpolation function; determining the brake calibration parameters according to the target deceleration array, each group of first interpolation functions, target pedal stroke data and each group of second interpolation functions to complete the calibration. The present application uses a first-order linear interpolation method to accurately adjust the pedal characteristics of the test vehicle according to the target deceleration data, thereby improving the calibration accuracy of the vehicle brake parameters.

[0019] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A flow chart of a vehicle brake pedal characteristic calibration method provided in an embodiment of the present application is shown;

[0022] Figure 2 A schematic diagram of a pedal force braking curve provided in an embodiment of the present application is shown;

[0023] Figure 3 A schematic diagram of a pedal stroke braking curve provided in an embodiment of the present application is shown;

[0024] Figure 4 A schematic diagram of a pedal characteristic curve provided in an embodiment of the present application is shown;

[0025] Figure 5 A functional module diagram of a vehicle brake pedal characteristic calibration device provided in an embodiment of the present application is shown;

[0026] Figure 6 A schematic structural diagram of an electronic device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0027] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art, under the guidance of the content of the present application, can add one or more other operations to the flowchart, or remove one or more operations from the flowchart.

[0028] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0029] Brake pedal characteristics are an important part of vehicle braking performance, and mainly refer to the relationship between the deceleration performance of the vehicle during braking and the brake pedal force / pedal stroke input by the driver. The integrated brake control system realizes mechanical decoupling in hardware, and its controllability is greatly improved compared to the traditional vacuum booster. The pedal feel simulator part has a relatively fixed pedal force-pedal stroke relationship, and can set the relationship between the pedal feel simulator's brake master cylinder push rod stroke and the servo cylinder piston displacement as needed, which facilitates the flexible calibration of the brake pedal characteristics.

[0030] The calibration input requirement for the integrated braking control system in terms of brake pedal characteristics is a finite number of elements in the brake master cylinder push rod stroke array and its corresponding servo cylinder pressure array. After inputting the determined calibration quantity, the integrated braking control system will interpolate and extend the calibration array, and adjust the pressure according to the driver's brake pedal input based on the calibration quantity through the PI control method.

[0031] At present, the technology of brake pedal characteristic calibration mainly involves how to realize the adjustable function of pedal characteristics from the hardware structure of integrated brake control system and how to test the brake pedal characteristics on a real vehicle or test bench. There are very few calibration methods for brake pedal characteristics.

[0032] Due to the lack of a systematic method for calibrating this characteristic in the industry, and the pedal characteristic calibration input requirements of the integrated braking control system and the limited data sampling rate during the test data acquisition process, the actual measured results are discrete signals, and the influence of random errors cannot be eliminated, resulting in unsatisfactory final calibration results.

[0033] Based on this, the embodiment of the present application provides a vehicle brake pedal characteristic calibration method and device, which uses a first-order linear interpolation method to accurately adjust the pedal characteristics of the test vehicle according to the target deceleration data to improve the calibration accuracy of the vehicle brake parameters, as follows:

[0034] See also Figure 1 , Figure 1 FIG. 1 is a flow chart showing a method for calibrating vehicle brake pedal characteristics provided by an embodiment of the present application. Figure 1As shown, the method provided in the embodiment of the present application comprises the following steps:

[0035] S100, performing a slow braking test on a test vehicle in a preset test environment, and collecting multiple groups of first braking test data through a preset data acquisition system.

[0036] Each set of first braking test data includes time history data of deceleration, pedal travel, pedal force, servo cylinder pressure and brake master cylinder push rod travel during the braking process.

[0037] S200: Determine pedal simulator availability according to multiple sets of first brake test data and preset pedal characteristic curves.

[0038] S300. If it is determined that the pedal simulator is available, the following processing is performed for each set of first brake test data: first-order linear interpolation is performed with the collected deceleration as the horizontal coordinate array and the servo cylinder pressure as the vertical coordinate array to obtain the first interpolation function, and first-order linear interpolation is performed with the collected pedal stroke as the horizontal coordinate array and the brake master cylinder push rod stroke as the vertical coordinate array to obtain the second interpolation function.

[0039] S400, determining a brake calibration parameter according to a target deceleration array, a first interpolation function corresponding to each set of first brake test data, target pedal travel data, and a second interpolation function corresponding to each set of first brake test data.

[0040] S500, writing the brake calibration parameters into the control software of the integrated brake control system, and determining whether the calibration is successful according to the pre-verification strategy. If the calibration is successful, the calibration of the brake pedal characteristics of the test vehicle is completed.

[0041] In step S100, the preset test conditions include: the test road surface is a dry, flat asphalt or concrete paved road surface, the slope of the test road over any 50-meter longitudinal length is less than 1%, the road crown slope is less than 2%, the maximum wind speed in the test environment is less than 5m / s, the average wind speed is less than or equal to 3m / s, the atmospheric temperature is 0℃~35℃, the test mass is the curb mass corresponding to the test vehicle plus a 180kg test load, the test load includes the driver and the test equipment, and the insufficient part is made up by the load object, the cold inflation pressure of the test vehicle tires meets the preset manufacturing technical regulations, specifically, the corresponding error of the cold inflation pressure of the test vehicle tires is less than or equal to 10kPa, and the slow braking test should be carried out in fine weather.

[0042] In this application, after the preset test conditions are determined, the method provided in this application also includes:

[0043] Before the test vehicle is subjected to a slow braking test, the test vehicle is controlled to perform brake running-in driving according to a preset brake running-in data table. The preset brake running-in data table includes the initial running-in braking speed, the final running-in braking speed, the average running-in deceleration, the braking operation and the number of running-in braking times. The braking operation is sudden braking. For each brake running-in driving, the following processing is performed: the brake temperature before braking is less than or equal to 150°C. After braking, the test vehicle is accelerated to the initial running-in braking speed within a preset time and maintains a constant speed. The brake temperature is less than or equal to 150°C before the next braking. During the braking period, the transmission is placed in N gear. After the brake is run-in according to the number of running-in braking times, the contact state of the brake friction element is checked. When the contact state of the brake friction element meets the design requirements, the test vehicle is subjected to a slow braking test in a preset test environment.

[0044] Table 1

[0045]

[0046] Table 1 provides a preset brake running-in data table provided in the present application. As shown in Table 1, the running-in braking initial speed is 80±1 (km / h), the running-in braking final speed is 40±1 (km / h), and the running-in average deceleration MFDD is 4±0.5 (m / s 2 ), the braking operation is sudden braking, and the number of running-in braking times is 300 times.

[0047] The test vehicle is to run in the brakes according to the running-in initial speed, running-in final speed, running-in MFDD and braking operation specified in Table 1. The brake temperature is less than or equal to 150°C before each braking. After each braking, the test vehicle is to accelerate to the running-in initial speed within the preset time and maintain a constant speed. When the brake temperature is less than or equal to 150°C, the next braking is performed. The whole process is to brake 300 times in total. During the braking period, the transmission is placed in N gear. After the brake running-in is completed, the contact state of the brake friction element is checked to ensure that it meets the design requirements.

[0048] After completing the above preliminary test preparations, a slow braking test is performed on the test vehicle under preset test conditions, and then multiple groups of first braking test data are collected according to the parameter collection data table.

[0049] Table 2

[0050] Acquisition parameters unit Accuracy time s ±0.1s speed km / h ±0.1km / h quality kg ±5kg Brake temperature ℃ ±5％ Deceleration <![CDATA[m / s 2 ]]> ±2％ Pedal force N ±2％ Pedal travel mm ±2％ Brake master cylinder push rod stroke mm ±2％ Servo cylinder pressure MPa ±2％

[0051] Table 2 is a parameter collection data table provided in an embodiment of the present application. As shown in Table 2, Table 2 provides the corresponding collection parameters, corresponding units of the collection parameters, and corresponding accuracy of the collection parameters during the slow braking test. Among them, the collection parameters include time, speed, mass, brake temperature, deceleration, pedal force, pedal stroke, brake main lever push rod stroke and servo cylinder pressure. Taking the deceleration collection parameter as an example, its corresponding unit is m / s 2 , which corresponds to an accuracy of ±2%.

[0052] In a preferred embodiment, the slow braking test includes:

[0053] The test vehicle is subjected to brake preheating driving, and multiple brake tests are performed on the test vehicle after the brake preheating driving in opposite directions between the starting point and the destination. For each brake test, the following processing is performed: the test vehicle is controlled to accelerate to a first preset speed, the transmission gear is at a target gear, the target gear is the highest gear that enables the test vehicle to stably maintain the first preset speed, the accelerator pedal is released and the target gear is maintained unchanged, and the test vehicle is controlled to start braking when the vehicle speed drops to a second preset speed. During the braking process, the following processing is performed: the brake pedal stroke is controlled to increase by less than or equal to a preset increment until the anti-lock braking system starts to work or the wheels of the test vehicle are locked, the target gear is maintained unchanged, the clutch is disengaged before the test vehicle stops, and the first brake test data generated during each brake test is collected through a preset data acquisition system.

[0054] In a specific implementation, before the slow braking test is formally carried out on the test vehicle, the test vehicle needs to be driven to warm up the brakes. The brake warming up of the test vehicle is carried out in the following manner:

[0055] Obtain a preset brake preheating data table, which includes brake preheating initial speed, brake preheating final speed, preheating average deceleration, braking operation, braking interval and preheating brake times. Control the test vehicle to travel at a constant speed according to the brake preheating initial speed. Control the test vehicle to perform multiple braking stops according to the braking interval and preheating brake times, so that the brake temperature of the test vehicle reaches the preset operating temperature. The preset operating temperature is between 70°C and 100°C.

[0056] Table 3

[0057]

[0058] Table 3 is a brake preheating data table provided in an embodiment of the present application. As shown in Table 3, the brake preheating data table includes a brake preheating initial speed, a brake preheating final speed, a preheating average deceleration, a braking operation, a braking interval, and a preheating braking number. The brake preheating initial speed is 75±1km / h, the preheating braking final speed is 0km / h, and the preheating average deceleration is 4±0.5m / s 2 The braking operation is sudden braking, the warm-up braking interval is 3±0.1km, and the number of warm-up braking times is 4.

[0059] Specifically, the test vehicle travels at a constant speed of 75km / h, brakes and stops every 3km, for a total of 4 times. Specific requirements are shown in Table 3. After stopping, it quickly accelerates to 75km / h and travels at a constant speed for the next braking (except the last time). After the preheating is completed, the vehicle should reach the preset operating temperature.

[0060] After the brake warm-up driving is completed, the test vehicle is formally subjected to multiple slow braking tests in both directions between the origin and the destination. Preferably, the first preset speed is 110km / h, the second preset speed is 105km / h, the preset increment is 30mm / s, and 5 slow braking tests are performed in each direction between the origin and the destination.

[0061] Specifically, for each slow braking test: accelerate the test vehicle to about 110km / h, and the transmission gear is in the highest gear that can stably maintain the vehicle speed. Release the accelerator pedal but keep the gear unchanged. Start braking when the vehicle speed drops to 105km / h (the error does not exceed ±2%). The brake pedal stroke increases in increments of no more than 30mm / s until the anti-lock braking system ABS starts to work or a wheel is locked. The gear is kept unchanged throughout the braking process (automatic transmission vehicles are in D gear). The clutch is disengaged when the test vehicle is about to stop. Direction correction is allowed during the test to keep the vehicle in a 3.5m wide lane. The first braking test data generated during each braking test is collected through a preset data acquisition system. The corresponding sampling frequency of the data acquisition system is not less than 100Hz, and the A / D module is above 16Bit.

[0062] In a preferred embodiment, in step S200, the pedal characteristic curve is determined in the following manner:

[0063] Define a target deceleration array corresponding to the test vehicle, the target deceleration array includes multiple target decelerations, determine a target pedal force array and a target pedal stroke array corresponding to the target deceleration array, the target pedal force array includes a target pedal force corresponding to each target deceleration, and the target pedal stroke array includes a target pedal stroke corresponding to each target deceleration, calculate a pedal force upper limit array and a pedal force lower limit array corresponding to the target pedal force array, and a pedal stroke upper limit array and a pedal stroke lower limit array corresponding to the target pedal stroke array according to preset accuracy requirements, the pedal force upper limit array includes a pedal force upper limit corresponding to each target pedal force, the pedal force lower limit array includes a pedal force lower limit corresponding to each target pedal force, the pedal stroke upper limit array includes a pedal stroke upper limit corresponding to each target pedal stroke, and the pedal stroke lower limit array includes a pedal stroke lower limit corresponding to each target pedal stroke, and draw a pedal characteristic curve according to the target deceleration array, the target pedal force array, the target pedal stroke array, the pedal force upper limit array, the pedal force lower limit array, and the pedal stroke upper limit array and the pedal stroke lower limit array.

[0064] In the specific implementation, define the target deceleration array a 目标 =(0.5,1,1.5,2,2.5…9.5,10)m / s 2 There are 20 target decelerations in total. The most ideal target pedal force and target pedal travel are set for each target deceleration based on vehicle engineering goals, benchmark analysis data, and empirical data. The target pedal force array F is defined. 目标 =(F1, F2, F3…F20), and the target pedal stroke array S 目标 = (S1, S, S3…S20), with a preset accuracy of ±5%, respectively, for the target pedal force array F 目标 and the target pedal travel array S 目标 Calculate and find the pedal force upper limit array F 上限 、Pedal force lower limit array F 下限 , and the pedal travel upper limit array S 上限 and pedal travel lower limit array S 下限 , then according to a 目标 、F 目标 , S 目标 、F 上限 、F 下限 , S 上限 and S 下限 , draw a pedal characteristic curve, the pedal characteristic curve includes a first pedal characteristic curve, a second pedal characteristic curve and a third pedal characteristic curve.

[0065] In another preferred embodiment, the pedal characteristic curve is drawn in the following manner:

[0066] The target deceleration array is used as the ordinate array, and the pedal force upper limit array, the target pedal force array and the pedal force lower limit array are used as the horizontal coordinate arrays, and cubic spline interpolation is performed in the first preset coordinate system to generate corresponding first pedal force braking curve, second pedal force braking curve and third pedal force braking curve. The target deceleration array is used as the ordinate array, and the target pedal stroke upper limit array, the pedal stroke array and the pedal stroke lower limit array are used as the horizontal coordinate arrays, and cubic spline interpolation is performed in the second preset coordinate system to generate corresponding first pedal stroke braking curve, second pedal stroke braking curve and third pedal stroke braking curve. The pedal force upper limit array is used as the horizontal coordinate array and the pedal stroke lower limit array is used as the vertical coordinate data, the pedal force lower limit array is used as the horizontal coordinate array and the pedal stroke upper limit array is used as the vertical coordinate data, the target pedal force array is used as the horizontal coordinate array and the target pedal stroke array is used as the vertical coordinate data, and cubic spline interpolation is performed in the third preset coordinate system to form corresponding first pedal characteristic curve, second pedal characteristic curve and third pedal characteristic curve in the third preset coordinate system.

[0067] In one specific embodiment, see Figure 2 , Figure 2 FIG. 2 shows a schematic diagram of a pedal force braking curve provided by an embodiment of the present application. Figure 2 As shown, using the scipy.interpolate.splrep function in the python-scipy library, respectively, with F 上限 is the horizontal coordinate array, a 目标 As the ordinate group, spline interpolation is performed in the first preset coordinate system to obtain the first pedal force braking curve F-1, and the scipy.interpolate.splrep function in the python-scipy library is used to calculate F 目标 is the horizontal coordinate array, a 目标 As the ordinate group, spline interpolation is performed in the first preset coordinate system to obtain the second pedal force braking curve F-2, and the scipy.interpolate.splrep function in the python-scipy library is used to calculate F 下限 is the horizontal coordinate array, a 目标 is a vertical coordinate group, and spline interpolation is performed in the first preset coordinate system to obtain a third pedal force braking curve F-3. During the drawing process, the boundary condition is set to a natural boundary.

[0068] See also Figure 3 , Figure 3 FIG. 1 shows a schematic diagram of a pedal travel braking curve provided in an embodiment of the present application. Figure 3As shown, using the scipy.interpolate.splrep function in the python-scipy library, S 上限 is the horizontal coordinate array, a 目标 As the ordinate group, spline interpolation is performed in the second preset coordinate system to obtain the first pedal stroke braking curve S-1, and the scipy.interpolate.splrep function in the python-scipy library is used to calculate the first pedal stroke braking curve S-1. 目标 is the horizontal coordinate array, a 目标 As the ordinate group, spline interpolation is performed in the second preset coordinate system to obtain the second pedal stroke braking curve S-2, and the scipy.interpolate.splrep function in the python-scipy library is used to calculate the second pedal stroke braking curve S-2. 下限 is the horizontal coordinate array, a 目标 is a vertical coordinate group, and spline interpolation is performed in the second preset coordinate system to obtain a third pedal stroke braking curve S-3. During the drawing process, the boundary condition is set to a natural boundary.

[0069] See also Figure 4 , Figure 4 FIG. 1 shows a schematic diagram of a pedal characteristic curve provided by an embodiment of the present application. Figure 4 As shown, using the scipy.interpolate.splrep function in the python-scipy library, respectively, with F 上限 is the horizontal coordinate array, S 下限 As the ordinate group, spline interpolation is performed in the third preset coordinate system to obtain the first pedal characteristic curve FS 上限 , using the scipy.interpolate.splrep function in the python-scipy library, with F 下限 is the horizontal coordinate array, S 上限 As the ordinate group, spline interpolation is performed in the third preset coordinate system to obtain the second pedal characteristic curve FS 目标 , using the scipy.interpolate.splrep function in the python-scipy library, with F 目标 is the horizontal coordinate array, S 目标 is a vertical coordinate group, and spline interpolation is performed in the third preset coordinate system to obtain the third pedal characteristic curve FS 下限 ,During the drawing process, the boundary conditions are set to natural boundaries.

[0070] In a preferred embodiment, step S200 includes:

[0071] The area between the first pedal characteristic curve and the vertical axis of the third preset coordinate system is defined as the first area, the area between the first pedal characteristic curve and the third pedal characteristic curve is defined as the second area, and the area between the third pedal characteristic curve and the horizontal axis of the third preset coordinate system is defined as the third area. For each group of first braking test data, first-order linear interpolation is performed with the collected pedal force as the horizontal coordinate array and the pedal stroke as the vertical coordinate array, and the corresponding test pedal characteristic curve is drawn in the third coordinate system. If the test pedal characteristic curve corresponding to each group of first braking test data is located in the second area, it is determined that the pedal simulator is available. If any group of first braking test data corresponds to a test pedal characteristic curve located in the first area or the third area, it is determined that the pedal simulator is unavailable.

[0072] Specifically, the first quadrant corresponding to the third preset coordinate system is FS 上限 and FS 下限 It is divided into three areas, namely the first area 1, the second area 2 and the third area 3.

[0073] In the present application, for each group of first braking test data, a test pedal force array is formed by multiple test pedal forces recorded in the group of first braking test data, and a test pedal stroke array is formed by multiple test pedal strokes recorded in the group of first braking test data. The test pedal force array and the test pedal stroke array are used according to the above-mentioned pedal characteristic curve creation method, and the intp.interp1d function in the python-scipy library is used to perform first-order linear interpolation, with the test pedal force array as the horizontal coordinate array and the test pedal stroke array as the vertical coordinate data, and the corresponding test pedal characteristic curve is drawn in the third coordinate system. If the test pedal characteristic curves corresponding to each group of first braking test data are all located in the second area 2 in the third preset coordinate system, it is determined that the pedal simulator characteristics meet the calibration requirements and the pedal fitter is determined to be available. If any test pedal characteristic curve is not in the second area 2, it is determined that the pedal simulator characteristics do not meet the calibration requirements, and the pedal fitter needs to be adjusted, and then return to re-execute step S100.

[0074] In a preferred embodiment, in steps S300 to S400, the brake calibration parameters include an average target pressure array and an average target master cylinder push rod stroke array, wherein steps S300 to S400 include:

[0075] For each group of first braking test data, the following processing is performed: the collected deceleration is filtered using the Savitzky-Golay filtering algorithm, and the filtered deceleration is used as the horizontal coordinate array and the servo cylinder pressure is used as the vertical coordinate array for first-order linear interpolation to obtain a first interpolation function, and the target pedal stroke array is substituted as the independent variable into the first interpolation function to obtain a target pressure array, and the collected pedal stroke is used as the horizontal coordinate array and the brake master cylinder push rod stroke is used as the vertical coordinate array for first-order linear interpolation to obtain a second interpolation function, and the target pedal stroke array is substituted as the independent variable into the second interpolation function to obtain the corresponding push rod stroke array, and the average of the bit elements of the target pressure array corresponding to each group of first braking test data is obtained to obtain an average target pressure array, and the average of the bit elements of the push rod stroke array of each group of first braking test data is obtained to obtain an average target master cylinder push rod stroke array.

[0076] In a specific embodiment, since the measurement of the vehicle deceleration signal may be interfered by the vehicle vibration caused by the unevenness of the road surface, in order to ensure the accurate capture of the feature points, after determining that the pedal simulator is available, it is necessary to use the Savitzky-Golay filtering algorithm to first filter the deceleration signal in each group of the first braking test data. In the Savitzky-Golay filtering algorithm, the window length is set to 21 and the polynomial coefficient is set to 2.

[0077] Due to the limited sampling frequency of the data acquisition system, it is impossible to accurately collect the characteristic points corresponding to the target deceleration array / target pedal travel data / target pedal force array. Therefore, it is necessary to interpolate the collected deceleration, pedal travel, pedal force, servo cylinder pressure and brake master cylinder push rod travel respectively, so as to eliminate the interference caused by random errors to the greatest extent by solving the average value. Since the sampling frequency of the data acquisition system itself is relatively high, in order to reduce the amount of computer calculations, first-order linear interpolation can be used for the data. Specifically, for each group of the first brake test data:

[0078] Use the intp.interp1d function in the python-scipy library to perform first-order linear interpolation with the filtered deceleration signal as the horizontal coordinate array and the servo cylinder pressure signal as the vertical coordinate array to obtain the first interpolation function p=f1(a). Then, convert the target deceleration array a 目标 As an independent variable, the first interpolation function p=f1(a) corresponding to each set of first braking test data is respectively introduced to obtain the target pressure array P corresponding to each set of first braking test data. 目标 , for each group of first braking test data corresponding to the target pressure array P 目标 Solve the average value of the elements in the array to form a new array and get the average target pressure array

[0079] Furthermore, since the actual calibration parameter corresponding to the integrated control system uses the brake master cylinder push rod stroke, and the characteristic point uses the pedal stroke, these two quantities need to be converted.

[0080] Specifically, for each set of first brake test data:

[0081] Use the intp.interp1d function in the python-scipy library to perform first-order linear interpolation with the collected pedal stroke signal as the horizontal coordinate array and the brake master cylinder push rod stroke signal as the vertical coordinate array to obtain the second interpolation function S 推杆 =f2(S), the target pedal stroke array S 目标 Substitute S as the independent variable 排杆 =f2(S), and obtain the push rod stroke array corresponding to this set of test data.

[0082] Then, the average element of the push rod stroke array corresponding to each group of the first brake test data is calculated and a new array is formed to obtain the average target master cylinder push rod stroke array

[0083] In a preferred embodiment, step S500 further includes:

[0084] The slow braking test is performed on the test vehicle again, and multiple groups of second braking test data are collected through a preset data acquisition system. For each group of second braking test data, first-order linear interpolation is performed with the collected deceleration as the horizontal coordinate array and the pedal stroke as the vertical coordinate array to obtain a third interpolation function, and the target deceleration array is substituted as an independent variable into the third interpolation function corresponding to each group of second braking test data to obtain an actual pedal stroke array corresponding to each group of second braking test data, and the average value of each corresponding element in the multiple actual pedal stroke arrays is obtained to obtain a target actual pedal stroke array, and it is determined whether each element in the target actual pedal stroke array satisfies the corresponding pedal stroke. If each element in the target actual pedal stroke array satisfies the corresponding pedal stroke upper limit and pedal stroke lower limit, the calibration is determined to be successful, and the average target master cylinder push rod stroke array and the average target pressure array are determined as brake pedal characteristic calibration parameters to complete the calibration. If any element in the target actual pedal stroke array does not satisfy the corresponding pedal stroke upper limit and pedal stroke lower limit, the calibration is determined to have failed, and parameter correction processing is performed on the average target pressure array. The corrected average target pressure array and average target master cylinder push rod stroke array are re-written into the control software of the integrated brake control system until the calibration is successful.

[0085] In one example, the average target master cylinder push rod stroke array determined in step S400 is and average target pressure array They are flashed into the control software of the integrated braking control system as independent variables and dependent variables respectively. After the flashing is completed, multiple groups of slow braking tests are performed on the test vehicle again according to step S100, and multiple groups of second braking test data are recorded. The second braking test data are similar to the first braking test data and will not be repeated here.

[0086] The deceleration signal in each set of the second braking test data is filtered. For each set of the second braking test data, the intp.interp1d function in the python-scipy library is used to perform first-order linear interpolation with the filtered deceleration signal as the horizontal coordinate array and the pedal travel signal as the vertical coordinate array to obtain the third interpolation function S-f3(a). The target deceleration array a is converted into 目标 As the independent variable, S-f3(a) corresponding to each set of second brake test data is respectively introduced to obtain the pedal stroke array S corresponding to each set of second brake test data. 实测 , for each set of second brake test data corresponding to the pedal travel array S 实测 Calculate the average value of each pair of elements in the array to form a new array and obtain the target measured pedal stroke array

[0087] Then further determine the target measured pedal stroke array Do the elements in satisfy If satisfied, the average target master cylinder push rod stroke array and average target pressure array The brake pedal characteristic calibration parameters are determined and the calibration test is completed. If the parameters are not met, the average target pressure array needs to be adjusted. Make corrections and retest.

[0088] In a preferred embodiment, the parameter modification process includes:

[0089] For each group of second braking test data, first-order linear interpolation is performed with the pedal stroke as the horizontal coordinate array and the deceleration as the vertical coordinate array to obtain a fourth interpolation function, and each element in the target pedal stroke array is substituted into the fourth interpolation function as an independent variable in turn to obtain a corresponding actual deceleration array, and the average value of each corresponding element in the actual deceleration array corresponding to each group of second braking test data is calculated, and the target actual deceleration array is obtained. For each element in the target actual deceleration array and the target deceleration array, the corresponding deviation coefficient is calculated to form a deviation array, wherein the deviation coefficient = (target deceleration - actual deceleration) / target deceleration. Through the deviation array, each element in the average target pressure array is corrected to obtain a corrected average target pressure array, wherein each element in the corrected average target pressure array = the average target pressure corresponding to the element × (1 + the deviation coefficient corresponding to the element).

[0090] In a specific embodiment, for each set of second braking test data, the intp.interp1d function in the python-scipy library is used to perform first-order linear interpolation with the filtered pedal stroke as the horizontal coordinate array and the deceleration signal as the vertical coordinate array to determine the fourth interpolation function a=f4(S) corresponding to each set of second braking test data.

[0091] For each set of second brake test data, the target pedal stroke array S 目标 Each element in is substituted as an independent variable into the fourth interpolation function a=f4(S) corresponding to the second braking test data in turn to obtain the corresponding actual deceleration array a corresponding to the second braking test data. 实际 , for each group of second braking test data corresponding to the actual deceleration array a 实际 Calculate the average value of each pair of elements in the array to form a new array and obtain the target actual deceleration array

[0092] For the target actual deceleration array and the target deceleration array α 目标 For each element in , the corresponding deviation coefficient is calculated according to the following formula and forms a deviation array δ:

[0093]

[0094] For the average target pressure array Each element in is corrected as follows and forms the corrected average target pressure array

[0095]

[0096] Further, and the corrected average target pressure array Use them as the independent variable and dependent variable of the calibration parameters respectively, repeat the relevant steps in the above parameter flashing and testing, and iteratively optimize the calibration parameters until the test results meet the expected requirements.

[0097] The benefits of this application are:

[0098] The key points of the present invention are the calculation method of the target pedal characteristic range, the typical test conditions, the calculation method of the initial calibration parameters, the data processing method after the test and the calibration parameter correction method.

[0099] The method of calculating the target pedal characteristic range of the present invention is to set the target pedal force / pedal stroke array based on the target deceleration array and the upper and lower limits of ±5%. This is the best calculation method summarized based on experimental experience in combination with the pedal characteristic calibration input requirements of the integrated braking control system.

[0100] The method of the present invention uses a target pedal force / pedal stroke upper and lower limit array to draw a curve through cubic spline function interpolation and draws a curve through test results to determine whether the pedal simulator meets the requirements. It is the simplest method for determining the availability of a pedal simulator designed based on the pedal characteristic calibration input requirements of an integrated braking control system and the mechanical decoupling characteristics.

[0101] The increase rate of the brake pedal stroke in the slow braking test in the test condition of the present invention does not exceed 30mm / s. This is an optimal test method designed based on the pressure building characteristics of the integrated braking control system based on PI control and test experience to ensure the servo cylinder pressure tracking performance and consistency of the test results.

[0102] The method of using the Savitzky-Golay filtering algorithm for the braking deceleration signal in the present invention is the best filtering method summarized based on the deceleration signal fluctuation characteristics caused by uneven road surface in actual vehicle tests and experimental experience, and can effectively reduce the influence of deceleration fluctuation on feature point capture.

[0103] The method adopted by the present invention in the data processing process is to perform first-order linear interpolation on the test data and substitute the feature point array into the interpolation function to obtain the average feature point array for multiple groups of data. This is the best method for obtaining the average value designed according to the requirements of the pedal characteristic calibration input of the integrated braking control system and the characteristics that the data sampling rate is limited in the test data acquisition process, resulting in the measured result being a discrete signal. It can effectively eliminate the influence of random errors and achieve more accurate feature point capture.

[0104] The method of the present invention, which interpolates test results and calculates deviation coefficients to correct calibration quantities, is the best method for correcting calibration quantities designed based on brake system characteristics and test experience. It can continuously approach results to a target interval through iterative parameters, thereby improving calibration efficiency and accuracy.

[0105] Based on the same application concept, the embodiment of the present application also provides a vehicle brake pedal characteristic calibration device corresponding to the vehicle brake pedal characteristic calibration method provided in the above embodiment. Since the principle of solving the problem by the device in the embodiment of the present application is similar to the vehicle brake pedal characteristic calibration method in the above embodiment of the present application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0106] See also Figure 5 , Figure 5FIG. 2 shows a functional module diagram of a vehicle brake pedal characteristic calibration device provided by an embodiment of the present application. Figure 5 As shown, the device provided by the present application includes:

[0107] The braking test module 600 is used to perform a slow braking test on the test vehicle under preset test conditions, and collect multiple groups of first braking test data through a preset data acquisition system, each group of first braking test data includes time history data of deceleration, pedal travel, pedal force, servo cylinder pressure and brake master cylinder push rod travel during braking;

[0108] A usability testing module 610, for determining the usability of the pedal simulator according to the plurality of sets of first brake test data and the preset pedal characteristic curve;

[0109] The interpolation module 620 is used to perform the following processing for each set of first brake test data if it is determined that the pedal simulator is available: perform first-order linear interpolation with the collected deceleration as the horizontal coordinate array and the servo cylinder pressure as the vertical coordinate array to obtain a first interpolation function, and perform first-order linear interpolation with the collected pedal stroke as the horizontal coordinate array and the brake master cylinder push rod stroke as the vertical coordinate array to obtain a second interpolation function;

[0110] A brake calibration parameter determination module 630, for determining a brake calibration parameter according to the target deceleration array, the first interpolation function corresponding to each set of first brake test data, the target pedal travel data, and the second interpolation function corresponding to each set of first brake test data;

[0111] The calibration module 640 is used to write the brake calibration parameters into the control software of the integrated brake control system to complete the calibration of the brake pedal characteristics of the test vehicle.

[0112] Based on the same application idea, please refer to Figure 6 , Figure 6 The structure diagram of an electronic device provided by an embodiment of the present application is shown. The electronic device 700 includes: a processor 710, a memory 720 and a bus 730, the memory 720 stores machine-readable instructions executable by the processor 710, when the electronic device 700 is running, the processor 710 and the memory 720 communicate through the bus 730, and the machine-readable instructions are executed by the processor 710 when running, as in the steps of the vehicle brake pedal characteristic calibration method provided in any of the above embodiments.

[0113] Based on the same application concept, an embodiment of the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the vehicle brake pedal characteristic calibration method provided in the above embodiment are executed.

[0114] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In the several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0115] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple 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.

[0116] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0117] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0118] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A vehicle brake pedal characteristic calibration method, characterized in that: The method comprises: Perform a slow braking test on the test vehicle under preset test conditions, and collect multiple groups of first braking test data through a preset data acquisition system, each group of first braking test data includes time history data of deceleration, pedal stroke, pedal force, servo cylinder pressure, and brake master cylinder push rod stroke during braking; determining the pedal simulator usability according to the plurality of sets of first brake test data and the preset pedal characteristic curve; If it is determined that the pedal simulator is available, the following processing is performed for each set of first brake test data: Perform first-order linear interpolation using the collected deceleration as the horizontal coordinate array and the servo cylinder pressure as the vertical coordinate array to obtain a first interpolation function; The collected pedal stroke is used as the abscissa array and the brake master cylinder push rod stroke is used as the ordinate array to perform first-order linear interpolation to obtain a second interpolation function; Determine a brake calibration parameter according to a target deceleration array, a first interpolation function corresponding to each set of first brake test data, target pedal travel data, and a second interpolation function corresponding to each set of first brake test data; The brake calibration parameters are written into the control software of the integrated brake control system to complete the calibration of the brake pedal characteristics of the test vehicle.

2. The method according to claim 1, characterized in that The pedal characteristic curve is determined by: defining a target deceleration array corresponding to the test vehicle, wherein the target deceleration array includes a plurality of target decelerations; Determine a target pedal force array and a target pedal stroke array corresponding to the target deceleration array, wherein the target pedal force array includes a target pedal force corresponding to each target deceleration, and the target pedal stroke array includes a target pedal stroke corresponding to each target deceleration; According to preset accuracy requirements, a pedal force upper limit array and a pedal force lower limit array corresponding to the target pedal force array, and a pedal stroke upper limit array and a pedal stroke lower limit array corresponding to the target pedal stroke array are respectively calculated, wherein the pedal force upper limit array includes the pedal force upper limit corresponding to each target pedal force, the pedal force lower limit array includes the pedal force lower limit corresponding to each target pedal force, the pedal stroke upper limit array includes the pedal stroke upper limit corresponding to each target pedal stroke, and the pedal stroke lower limit array includes the pedal stroke lower limit corresponding to each target pedal stroke; A pedal characteristic curve is drawn according to the target deceleration array, the target pedal force array, the target pedal stroke array, the pedal force upper limit array, the pedal force lower limit array, the pedal stroke upper limit array and the pedal stroke lower limit array.

3. The method according to claim 2, characterized in that The pedal characteristic curve includes a first pedal characteristic curve, a second pedal characteristic curve and a third pedal characteristic curve, The pedal characteristic curve is drawn in the following manner: Using the target deceleration array as the ordinate array, and using the pedal force upper limit array, the target pedal force array, and the pedal force lower limit array as the abscissa array, respectively, performing cubic spline interpolation in the first preset coordinate system, respectively, to generate the corresponding first pedal force braking curve, second pedal force braking curve, and third pedal force braking curve; Using the target deceleration array as the ordinate array, and using the target pedal stroke upper limit array, the pedal stroke array, and the pedal stroke lower limit array as the abscissa array, respectively, performing cubic spline interpolation in the second preset coordinate system, respectively, to generate corresponding first pedal stroke braking curve, second pedal stroke braking curve, and third pedal stroke braking curve; The pedal force upper limit array is used as the horizontal coordinate array, the pedal stroke lower limit array is used as the vertical coordinate data, the pedal force lower limit array is used as the horizontal coordinate array, the pedal stroke upper limit array is used as the vertical coordinate data, the target pedal force array is used as the horizontal coordinate array, and the target pedal stroke array is used as the vertical coordinate data, and cubic spline interpolation is performed respectively in the third preset coordinate system to form corresponding first pedal characteristic curve, second pedal characteristic curve and third pedal characteristic curve in the third preset coordinate system.

4. The method according to claim 1, characterized in that: The slow braking test includes: Performing brake warm-up driving on the test vehicle; Conducting multiple braking tests on the test vehicle after the brake warm-up driving in opposite directions between the origin and the destination; For each braking test, the following processing is performed: controlling the test vehicle to accelerate to a first preset vehicle speed, the transmission gear is in a target gear, the target gear is a highest gear that enables the test vehicle to stably maintain the first preset speed, releasing the accelerator pedal and maintaining the target gear unchanged, and controlling the test vehicle to start braking when the vehicle speed drops to a second preset vehicle speed; During braking, the following processing is performed: Controlling the brake pedal stroke to increase by a preset increment that is less than or equal to a preset increment until the anti-lock braking system starts to work or the wheels of the test vehicle are locked, maintaining the target gear position unchanged, and disengaging the clutch before the test vehicle stops; The first braking test data generated during each braking test by the target.

5. The method according to claim 3, characterized in that: Pedal simulator availability is determined by: The area between the first pedal characteristic curve and the vertical axis of the third preset coordinate system is defined as the first area, the area between the first pedal characteristic curve and the third pedal characteristic curve is defined as the second area, and the area between the third pedal characteristic curve and the horizontal axis of the third preset coordinate system is defined as the third area; For each set of first brake test data, first-order linear interpolation is performed using the collected pedal force as the abscissa array and the pedal stroke as the ordinate array, and a corresponding test pedal characteristic curve is generated in the third coordinate system; If the test pedal characteristic curve corresponding to each set of first brake test data is located within the second region, it is determined that the pedal simulator is available; If there is a test pedal characteristic curve corresponding to any set of first brake test data located within the first area or the third area, it is determined that the pedal simulator is unavailable.

6. The method according to claim 2, characterized in that The brake calibration parameters include an average target pressure array and an average target master cylinder push rod stroke array. Wherein, the braking calibration parameters are determined in the following manner: For each set of first braking test data, perform the following processing: The collected deceleration is filtered using the Savitzky-Golay filtering algorithm; Perform first-order linear interpolation using the filtered deceleration as the horizontal coordinate array and the servo cylinder pressure as the vertical coordinate array to obtain a first interpolation function; Substituting the target pedal stroke array as an independent variable into the first interpolation function to obtain a target pressure array; The collected pedal stroke is used as the abscissa array and the brake master cylinder push rod stroke is used as the ordinate array to perform first-order linear interpolation to obtain a second interpolation function; Substitute the target pedal stroke array as an independent variable into the second interpolation function to obtain the corresponding push rod stroke array; averaging the elements of the target pressure array corresponding to each group of first braking test data to obtain an average target pressure array; The average element of the push rod stroke array of each group of first brake test data is averaged to obtain an average target master cylinder push rod stroke array.

7. The method according to claim 2, characterized in that After writing the brake calibration parameters into the control software of the integrated brake control system, the method further includes: Re-performing the slow braking test on the test vehicle, and collecting multiple sets of second braking test data through a preset data acquisition system; For each set of second braking test data, first-order linear interpolation is performed with the collected deceleration as the abscissa array and the pedal stroke as the ordinate array to obtain a third interpolation function; Substituting the target deceleration array as an independent variable into the third interpolation function corresponding to each set of second braking test data, to obtain an actual pedal stroke array corresponding to each set of second braking test data; Calculate the average value of each pair of elements in multiple actual pedal stroke arrays to obtain a target actual pedal stroke array; Determining whether each element in the target actual pedal stroke array satisfies a corresponding pedal stroke upper limit and pedal stroke lower limit; If each element in the target actual pedal stroke array satisfies the corresponding pedal stroke upper limit and pedal stroke lower limit, the calibration is determined to be successful, and the average target master cylinder push rod stroke array and the average target pressure array are determined as brake pedal characteristic calibration parameters to complete the calibration; If any element in the target actual pedal stroke array does not satisfy the corresponding pedal stroke upper limit and pedal stroke lower limit, the calibration is determined to have failed, and parameter correction processing is performed on the average target pressure array. The corrected average target pressure array and the average target master cylinder push rod stroke array are re-written into the control software of the integrated braking control system until the calibration is successful.

8. The method according to claim 2, characterized in that: The parameter correction process includes: For each set of second braking test data, a first-order linear interpolation is performed with the pedal stroke as the abscissa array and the deceleration as the ordinate array to obtain a fourth interpolation function; Substituting each element in the target pedal stroke array as an independent variable into the fourth interpolation function in turn to obtain the corresponding actual deceleration array; Calculate the average value of each pair of elements in the actual deceleration array corresponding to each group of second braking test data, and obtain the target actual deceleration array; For each element in the target actual deceleration array and the target deceleration array, a corresponding deviation coefficient is calculated to form a deviation array, wherein the deviation coefficient=(target deceleration-actual deceleration) / target deceleration; Each element in the average target pressure array is corrected through the deviation array to obtain a corrected average target pressure array, wherein each element in the corrected average target pressure array = the average target pressure corresponding to the element × (1 + the deviation coefficient corresponding to the element).

9. The method according to claim 4, characterized in that The test vehicle is driven to warm up the brakes in the following manner: Obtaining a preset brake preheating data table, wherein the preset brake preheating data table includes a brake preheating initial speed, a brake preheating final speed, a preheating average deceleration, a braking operation, a braking interval, and a preheating braking number; Controlling the test vehicle to travel at a constant speed according to the brake preheating initial speed; The test vehicle is controlled to perform multiple braking stops according to the braking interval and the number of preheating braking times, so that the brake temperature of the test vehicle reaches a preset working temperature, and the preset working temperature is between 70°C and 100°C.

10. The method according to claim 1, characterized in that The method further comprises: Before performing a slow braking test on the test vehicle, the test vehicle is controlled to perform brake running-in driving according to a preset brake running-in data table, wherein the preset brake running-in data table includes a running-in braking initial speed, a running-in braking final speed, a running-in average deceleration, a braking operation and a running-in braking number, wherein the braking operation is an emergency braking; For each brake run-in, the following steps are performed: The brake temperature before braking is less than or equal to 150°C. After braking, the test vehicle accelerates to the initial running-in braking speed within a preset time and maintains a constant speed. The brake temperature is less than or equal to 150°C before the next braking. During the braking process, the transmission is placed in N gear; After the brake is run-in according to the number of running-in braking times, check the contact state of the brake friction element. When the contact state of the brake friction element meets the design requirements, perform a slow braking test on the test vehicle in a preset test environment.

11. The method according to claim 1, characterized in that: The preset test conditions include: The test road surface is dry, flat asphalt or concrete paved road; The slope of any 50-meter longitudinal length of the test road is less than 1%, the road hump slope is less than 2%, the maximum wind speed in the test environment is less than 5m / s, the average wind speed is less than or equal to 3m / s, and the atmospheric temperature is 0℃~35℃; The test mass is the corresponding curb mass of the test vehicle plus a 180kg test load; The cold inflation pressure of the tires of the test vehicle complies with the preset manufacturing technical regulations.

12. A vehicle brake pedal characteristic calibration device, characterized in that: The device comprises: A braking test module is used to perform a slow braking test on a test vehicle under preset test conditions, and collect multiple groups of first braking test data through a preset data acquisition system, each group of first braking test data includes time history data of deceleration, pedal travel, pedal force, servo cylinder pressure and brake master cylinder push rod travel during braking; A usability testing module, used for determining the usability of the pedal simulator according to the plurality of sets of first brake test data and a preset pedal characteristic curve; The interpolation module is used for, if it is determined that the pedal simulator is available, performing the following processing for each set of first brake test data: performing first-order linear interpolation with the collected deceleration as the horizontal coordinate array and the servo cylinder pressure as the vertical coordinate array to obtain a first interpolation function, and performing first-order linear interpolation with the collected pedal stroke as the horizontal coordinate array and the brake master cylinder push rod stroke as the vertical coordinate array to obtain a second interpolation function; A braking calibration parameter determination module, used to determine the braking calibration parameters according to the target deceleration array, the first interpolation function corresponding to each set of first braking test data, the target pedal travel data and the second interpolation function corresponding to each set of first braking test data; The calibration module is used to write the brake calibration parameters into the control software of the integrated brake control system to complete the calibration of the brake pedal characteristics of the test vehicle.

Images