Method for evaluating braking safety of automobile braking system

Abstract

The application provides a kind of automobile brake system brake safety evaluation method, by in real-time operation of vehicle, obtain multiple groups of effective brake pedal displacement data and vehicle deceleration data, get the function relationship of vehicle deceleration and brake pedal displacement, according to the function relationship of vehicle deceleration and brake pedal displacement obtained, the corresponding brake pedal displacement amount is obtained by bringing the numerical value of each vehicle deceleration detection point, the brake safety degree of vehicle and the brake pedal displacement deviation rate of each deceleration detection point are judged based on the original factory brake safety range of vehicle, the real-time evaluation of automobile brake performance is realized, which can help the driver quickly understand the state of automobile brake system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle testing, in particular to a brake safety evaluation method for an automobile brake system. BACKGROUND

[0002] The automobile brake system is crucial in ensuring the safety of automobile driving, and with the rapid development of highways and the increasing traffic density, it is necessary for the driver to have a certain control over the effectiveness of the automobile brake system to ensure the driving safety of himself and passengers.

[0003] Currently, the automobile brake performance evaluation methods mainly include road test method and bench test method. The road test method is to set detection instruments on the tested automobile to detect the braking distance, braking deceleration and braking time of the automobile during driving on the road. The bench test method is to send the automobile to a designated place to detect the braking performance according to the needs of detection.

[0004] Both of the above-mentioned automobile brake performance evaluation methods need to interrupt the normal use of the automobile, and need professional personnel to use specific instruments or go to specific places for detection, which is complicated and has poor real-time performance, greatly consuming the time of the driver.

[0005] Therefore, during the long-term use of the automobile, most drivers experience the relationship between the pedal stroke, pedal force and vehicle deceleration through subjective experience to evaluate the pros and cons of the automobile brake performance. The way of evaluating the automobile brake performance through subjective experience has uncertainty and is not suitable for the current development of automobile intelligence. SUMMARY

[0006] The present application provides a brake safety evaluation method for an automobile brake system, which aims to evaluate the automobile brake performance in real time and quickly understand the state of the automobile brake system.

[0007] The basic scheme of the present application is a brake safety evaluation method for an automobile brake system, comprising the following steps:

[0008] S1: obtaining a plurality of sets of effective brake pedal displacement data and vehicle deceleration data in real-time operation of the vehicle;

[0009] S2: performing quadratic curve fitting on the obtained brake pedal displacement data and vehicle deceleration data to obtain a functional relationship between the vehicle deceleration and the brake pedal displacement;

[0010] S3: based on the obtained functional relationship between the vehicle deceleration and the brake pedal displacement, inputting the values of each vehicle deceleration detection point to obtain the corresponding brake pedal displacement, and judging the vehicle brake safety degree and the brake pedal displacement deviation rate of each deceleration detection point based on the original factory brake safety range of the vehicle.

[0011] S4: outputting the vehicle braking safety degree and the deviation rate of each deceleration detection point by using the vehicle-mounted display device.

[0012] The above scheme realizes real-time evaluation of the automobile braking performance, and helps the driver quickly understand the state of the automobile braking system, by obtaining multiple sets of effective brake pedal displacement data and vehicle deceleration data in real-time operation of the vehicle, obtaining the functional relationship between the vehicle deceleration and the brake pedal displacement, inputting the values of each vehicle deceleration detection point into the obtained functional relationship between the vehicle deceleration and the brake pedal displacement to obtain the corresponding brake pedal displacement, and judging the vehicle braking safety degree and the brake pedal displacement deviation rate of each deceleration detection point based on the original factory braking safety range of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The flowchart of the automobile braking system braking safety evaluation method of the application is shown in the figure.

[0014] Figure 2 The figure is a data example of brake pedal displacement.

[0015] Figure 3 The figure is a data example of effective brake pedal displacement.

[0016] Figure 4 The figure is a data example of effective vehicle braking data.

[0017] Figure 5 The figure is a data example of the relationship between vehicle deceleration and brake pedal displacement.

[0018] Figure 6 The figure is a data example of the vehicle braking safety range.

[0019] Figure 7 The figure is a data example of the relationship between the fitting curve and the braking safety range.

[0020] Figure 8 The figure is a data example of the vehicle braking safety level. DETAILED DESCRIPTION

[0021] An automobile braking system braking safety evaluation method comprises the following steps:

[0022] S1: obtaining multiple sets of effective brake pedal displacement data and vehicle deceleration data in real-time operation of the vehicle;

[0023] S2: performing quadratic curve fitting on the obtained brake pedal displacement data and vehicle deceleration data to obtain the functional relationship between the vehicle deceleration and the brake pedal displacement;

[0024] S3: According to the obtained function relationship between the vehicle deceleration and the brake pedal displacement, the corresponding brake pedal displacement value is obtained by substituting the numerical value of each vehicle deceleration detection point, and the vehicle braking safety degree and the brake pedal displacement deviation rate of each deceleration detection point are determined based on the vehicle original factory braking safety range;

[0025] S4: The vehicle braking safety degree and the brake pedal displacement deviation rate of each deceleration detection point are output by using the vehicle display device.

[0026] Specifically, in the above step S1, a plurality of sets of effective brake pedal displacement data and vehicle deceleration data are obtained by setting brake pedal displacement sensors and vehicle speed sensors. When the vehicle is started, the current vehicle deceleration and brake pedal displacement are input by the sensors. If the brake pedal displacement at the current time is greater than or equal to the brake pedal displacement at the previous time, it indicates that the driver is further stepping on the brake pedal, and the vehicle deceleration is equal to the current vehicle deceleration, and the brake pedal displacement is equal to the current brake pedal displacement. On the contrary, if the brake pedal displacement at the current time is less than the brake pedal displacement at the previous time, the previous vehicle deceleration is equal to the current vehicle deceleration, and the previous brake pedal displacement is equal to the current brake pedal displacement. That is, the effective brake pedal displacement data is the pedal displacement data from the pedal position stepped by the driver to the maximum pedal displacement position.

[0027] Then in step S2, the obtained brake pedal displacement data and vehicle deceleration data are fitted by a quadratic curve through the least square method to obtain the function relationship between the vehicle deceleration and the brake pedal displacement.

[0028] Then in step S3, according to the vehicle original factory braking safety range, the upper and lower bounds U and L of the safety range of the brake pedal displacement corresponding to the vehicle deceleration.

[0029] The numerical value of the set vehicle deceleration detection point is substituted into the function relationship between the vehicle deceleration and the brake pedal displacement to obtain the corresponding brake pedal displacement value. If the brake pedal displacement value is less than or equal to the upper bound of the corresponding brake pedal displacement safety range, or greater than or equal to the lower bound of the brake pedal displacement safety range, the safety level is increased by 1, and the deviation rate is calculated. If the brake pedal displacement value is greater than the upper bound of the corresponding brake pedal displacement safety range, or less than the lower bound of the brake pedal displacement safety range, the safety level remains unchanged, and the deviation rate is 100%.

[0030] The brake pedal displacement deviation rate of each deceleration detection point is calculated according to the following formula:

[0031]

[0032] In the above formula:

[0033] DR(i) represents the displacement deviation rate of the current vehicle deceleration detection point;

[0034] s represents the value of the vehicle deceleration detection point into the function of the vehicle deceleration and brake pedal displacement to get the corresponding brake pedal displacement value;

[0035] U(i), L(i) represent the upper and lower limits of the brake pedal displacement safety range of the current vehicle deceleration detection point;

[0036] abs represents abs(number) means taking the absolute value of the number in the parentheses;

[0037] Array subscript i represents the order of the vehicle deceleration detection point.

[0038] The vehicle braking safety degree is calculated according to the following formula:

[0039] RANK = GI / LEN

[0040] In the above formula:

[0041] RANK represents the vehicle braking safety degree;

[0042] GI represents the number of elements within the original factory braking safety range;

[0043] LEN represents the number of elements of the vehicle deceleration test point.

[0044] When the size of i is greater than the number of elements of the vehicle deceleration test point LEN, the vehicle braking safety degree RANK and the deviation rate DR of each deceleration detection point are output.

[0045] The starting level of the safety level is 0, and if the brake pedal displacement value is less than or equal to the upper limit of the corresponding brake pedal displacement safety range and greater than or equal to the lower limit of the brake pedal displacement safety range, the safety level is increased by 1.

[0046] In the last step S4, when the size of i is greater than the number of elements of the vehicle deceleration test point LEN, the vehicle braking safety degree RANK and the deviation rate DR of each deceleration detection point are output by the on-board display device.

[0047] Example 1

[0048] First, the scheme needs to obtain vehicle braking data through sensors in real-time operation of the vehicle, and the brake pedal displacement is as shown in Figure 2 The effective brake pedal displacement in step S1 of the method is as shown in Figure 3 Figure 2 The brake pedal displacement in the above formula has left and right two, and the effective brake pedal displacement data is the pedal displacement data of the driver stepping on the pedal, that is, the left brake pedal displacement is the effective brake pedal displacement. The effective vehicle braking data is obtained by combining the effective brake pedal displacement data with the vehicle deceleration data as​Figure 4 As shown.

[0049] right Figure 4 The effective vehicle braking data was fitted using the least squares method to obtain a quadratic curve, yielding the functional relationship between vehicle deceleration and brake pedal displacement, as shown below. Figure 5 As shown. Figure 5 The functional relationship expression for label 1 is y = 10.0709 + 98.4655x - 42.9134x 2 .

[0050] In this specific embodiment, five vehicle deceleration points are set, with V = [0, 1, 0, 2, 0, 3, 0, 6, 0, 8]. The upper and lower limits of the vehicle's original factory braking safety range in this specific embodiment are U = [1322284045] and L = [2534405055], respectively. The specific braking safety range is as follows: Figure 6 As shown.

[0051] By substituting the values ​​of the pre-defined vehicle deceleration detection points into the functional relationship between vehicle deceleration and brake pedal displacement, the corresponding brake pedal displacement value is obtained. The relationship between the fitted curve of vehicle deceleration and brake pedal displacement and the braking safety range is then established. Figure 7 As shown.

[0052] Depend on Figure 7 It can be seen that the vehicle deceleration is within the safe zone when it is 0.1, 0.2, and 0.3, and is not within the safe zone when it is 0.6 and 0.8.

[0053] Therefore, the current security level is 3. From RANK = GI / LEN, GI = 3, LEN = 5, we can deduce that RANK = 60%.

[0054]

[0055] DR(i) represents the displacement deviation rate of the current vehicle deceleration detection point;

[0056] 's' represents substituting the values ​​of the vehicle deceleration detection points into the functional relationship between vehicle deceleration and brake pedal displacement to obtain the corresponding brake pedal displacement value.

[0057] U(i) and L(i) represent the upper and lower bounds of the safe range of brake pedal displacement at the current vehicle deceleration detection point;

[0058] abs stands for abs(number), meaning to take the absolute value of the number inside the parentheses;

[0059] Therefore, the deceleration detection point deviation rates of D1, D2 and D3 are DR(1)=8.14%, DR(2)=0.79% and DR(3)=29.14% respectively. Since the vehicle deceleration is 0.6 and 0.8, the brake pedal displacement is not in the safe range, so the deceleration detection point deviation rates of D4 and D5 are 100%.

[0060] When the five vehicle deceleration points are all calculated, if the size of i is greater than the element number of the vehicle deceleration test points, the vehicle braking safety degree and the deviation rates of the deceleration detection points are output by using the on-board display device. As shown in FIG. 6, the vehicle braking safety degree RANK is 60%, and the deviation rates of the deceleration detection points are 8.14%, 0.79%, 29.14%, 100% and 100% respectively. Figure 8

[0061] The present application has the ability to judge the vehicle braking safety degree and the deceleration detection point deviation rates based on the original vehicle braking safety range, realizes the real-time evaluation of the automobile braking performance, and helps the driver to quickly understand the state of the automobile braking system.​

Claims

1. A method for evaluating the safety of a brake system of an automobile, characterized by, The method comprises the following steps: S1: in real-time operation of the vehicle, a plurality of sets of effective brake pedal displacement data and vehicle deceleration data are acquired; S2: the acquired brake pedal displacement data and vehicle deceleration data are subjected to quadratic term curve fitting to obtain a functional relationship between the vehicle deceleration and the brake pedal displacement; S3: according to the obtained functional relationship between the vehicle deceleration and the brake pedal displacement, the numerical values of each vehicle deceleration detection point are substituted to obtain corresponding brake pedal displacement amounts, and the vehicle braking safety degree and the brake pedal displacement deviation rate of each deceleration detection point are judged based on the original factory braking safety range of the vehicle; S4: the vehicle braking safety degree and the deviation rate of each deceleration detection point are output by using a vehicle-mounted display device.

2. The automobile braking system braking safety evaluation method according to claim 1, characterized in that: The acquired brake pedal displacement data and vehicle deceleration data are subjected to quadratic term curve fitting by using the least square method to obtain a functional relationship between the vehicle deceleration and the brake pedal displacement.

3. The method of claim 2, wherein: The numerical values of the vehicle deceleration detection points are substituted into the functional relationship between the vehicle deceleration and the brake pedal displacement to obtain corresponding brake pedal displacement values, if the brake pedal displacement value is less than or equal to the upper limit of the corresponding brake pedal displacement safety range and greater than or equal to the lower limit of the brake pedal displacement safety range, the safety level is increased by 1, and the deviation rate is calculated, if the brake pedal displacement value is greater than the upper limit of the corresponding brake pedal displacement safety range or less than the lower limit of the brake pedal displacement safety range, the safety level is unchanged, and the deviation rate is 100%.

4. The automobile braking system braking safety evaluation method according to claim 3, characterized in that: According to the original factory braking safety range of the vehicle, the upper and lower limits of the safety range of the brake pedal displacement amount corresponding to the vehicle deceleration are U and L respectively.

5. The method of claim 4, wherein: The brake pedal displacement deviation rate of each deceleration detection point is calculated according to the following formula: ， In the above formula: DR(i) represents the displacement deviation rate of the current vehicle deceleration detection point; s represents that the numerical values of the vehicle deceleration detection points are substituted into the functional relationship between the vehicle deceleration and the brake pedal displacement to obtain corresponding brake pedal displacement values; U(i), L(i) represent the upper and lower limits of the brake pedal displacement safety range of the current vehicle deceleration detection point; abs represents that abs(number) means taking the absolute value of the number in the parentheses; The array subscript i represents the order of the vehicle deceleration detection point.

6. The method of claim 4, wherein: The vehicle braking safety degree is calculated according to the following formula: RANK = GI / LEN In the above formula: RANK represents the vehicle braking safety degree; GI represents the number of elements located in the original factory braking safety range; LEN represents the number of elements of the vehicle deceleration test point.

7. The method of claim 5, wherein: When the size of i is greater than the number of elements of the vehicle deceleration test point LEN, the vehicle braking safety degree RANK and the deviation rate DR of each deceleration detection point are output.

8. The method of claim 1, wherein: The effective brake pedal displacement data is the pedal displacement data of the driver stepping on the pedal.

9. The method of claim 3, wherein: The starting level of the safety level is 0, if the brake pedal displacement value is less than or equal to the upper limit of the corresponding brake pedal displacement safety range and greater than or equal to the lower limit of the brake pedal displacement safety range, the safety level is increased by 1.

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