A simplified analysis and processing method for AEB braking curve characteristics

Abstract

The present invention belongs to the technical field of vehicle collision, and in particular, relates to a simplified analysis and processing method for an AEB braking curve feature, firstly, obtaining a braking curve of a vehicle collision; performing consistency analysis and difference analysis on the obtained braking curve, extracting the braking strategy, braking intensity and time factors in the waveform of the braking curve; then constructing a simplified braking curve model, using the extracted braking strategy, braking intensity and time factors as input data of the simplified braking curve model, and outputting a braking curve stage characteristic diagram; and analyzing the linear change of the braking curve in each braking curve stage characteristic diagram, generating a simplified braking curve of each braking curve stage, and connecting the simplified braking curves of each braking curve stage to generate a simplified characteristic curve of the entire braking curve stage. The present invention can solve the problem of inapplicability of the existing braking curve simplification method.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle collision, and in particular relates to a simplified analysis and processing method for an AEB braking curve feature. Background Art

[0002] Before a vehicle collision, the AEB system generates braking force, causing the vehicle's acceleration to change. This change is detected and recorded by the acceleration sensor, forming an acceleration change curve in the time domain. Different vehicles have different braking strategies when facing the same emergency conditions, which are usually divided into single-stage braking and double-stage braking. Since the collected braking curve itself has problems of mutation and noise interference, the curve-related features are hidden and difficult to extract.

[0003] At present, the commonly used method for simplifying the braking curve is curve fitting, among which the fitting methods include interpolation and least squares. The interpolation method estimates the approximate value at other points by taking the value of a finite number of function points, but in fact, due to the large number of braking waveform data points, the interpolation method will require a higher degree of interpolation polynomial, which lacks engineering significance. Although the least squares method can minimize the sum of square errors of the fitting curve, the braking waveform has unknown inflection points in the time domain, and it is not a single linear relationship, which causes the fitting curve to lose important features.

[0004] Therefore, the currently popular curve simplification methods are not suitable for the simplification of braking curves. The corresponding curve simplification methods such as interpolation and least squares method lack engineering significance and cannot reflect the actual significance of the acceleration representation in the corresponding time node and curve. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a simplified analysis and processing method for AEB braking curve characteristics to solve the problem of inapplicability of existing braking curve simplification methods.

[0006] The basic solution provided by the present invention is a simplified analysis and processing method for AEB braking curve characteristics, comprising:

[0007] S1: Obtain the braking curve of vehicle collision;

[0008] S2: Perform consistency analysis and difference analysis on the acquired braking curve to extract the braking strategy, braking intensity and time factors in the waveform of the braking curve;

[0009] S3: construct a simplified model of the braking curve, use the extracted braking strategy, braking intensity and time factors as input data of the simplified model of the braking curve, and output a stage characteristic diagram of the braking curve;

[0010] S4: Analyze the linear change of the braking curve in each braking curve stage characteristic diagram, generate a simplified braking curve for each braking curve stage, and connect the simplified braking curves for each braking curve stage to generate a simplified characteristic curve for the entire braking curve stage.

[0011] Further, the S1 includes:

[0012] S1-1: The vehicle longitudinal deceleration is greater than 0.5m / s 2 AEB is activated at 0.5m / s 2 The braking curve is aligned with the reference moment, and the braking curve data 1 second before and after AEB activation are obtained;

[0013] S1-2: Filter the acquired braking curve data to obtain a processed braking curve.

[0014] Further, the S2 includes:

[0015] S2-1: Take the average of multiple braking curves of the same vehicle model under the same emergency braking condition according to the time points, fit the average values ​​at the corresponding time points into a curve, and generate a mean fitting curve;

[0016] S2-2: Draw the braking curves of different models on the same graph according to the time points and remove abnormal curves;

[0017] S2-3: After the consistency analysis of S2-1 and the difference analysis of S2-2, the braking strategy, braking intensity and time factors to reach steady state are extracted according to the trend of the braking curve waveform.

[0018] Further, the S3 includes:

[0019] S3-1: constructing a simplified braking curve model, wherein the simplified braking curve model is a time-acceleration coordinate model;

[0020] S3-2: The extracted braking strategy, braking intensity and time factors are used as input data of the simplified braking curve model, and a braking curve stage characteristic diagram is output. The braking curve stage characteristics include an action stage, a braking hold stage and a braking release stage, and each braking curve stage characteristic corresponds to a braking intensity performance and a time performance.

[0021] Further, the S4 includes:

[0022] S4-1: Perform time domain analysis on the braking curve stage characteristic diagram in the simplified braking curve model, and calculate the speed at each moment according to the acceleration curve in the time domain. The calculation formula is:

[0023]

[0024] Among them, v n represents the speed at time n, t n represents the time n, a represents the acceleration;

[0025] S4-2: The area enclosed by the braking curve and the time axis in each braking curve stage characteristic diagram is represented as the speed change of the vehicle during the braking process, the speed change of the braking curve in each braking curve stage diagram is obtained, and converted into a linear change using an equivalent trapezoidal method;

[0026] S4-3: Connect the braking curves represented by the linear variation of each braking curve stage characteristic to generate a simplified braking curve diagram.

[0027] Further, the S4-2 is specifically:

[0028] The definition is that the action phase is the ab segment in the braking curve phase characteristic diagram, the brake holding phase is the bc segment in the braking curve phase characteristic diagram, and the brake release phase is the cd segment in the braking curve phase characteristic diagram;

[0029] When the observed value of the speed change is the same as the calculated value of the waveform of the braking curve, the waveform of the braking holding stage is equivalent to a constant, and the calculation formula is:

[0030]

[0031] Where, ΔV b-c It represents the speed change in the simplified model of the braking curve during the braking holding phase. represents the velocity at point c, represents the speed at point b;

[0032] The effective stage is equivalent to a linear change, and the calculation formula is:

[0033]

[0034] Among them, a represents the acceleration of segment bc, and k1 represents the slope of the acceleration of segment ab;

[0035] The brake release phase is equivalent to a linear change, and the calculation formula is:

[0036]

[0037] Among them, k2 represents the slope of the acceleration in the cd segment, and t3 represents the time at point d.

[0038] The principle and advantage of the present invention are as follows: In the present invention, for the technical solution of simplifying the braking curve characteristics, the acquired braking curve data is first filtered to obtain a braking curve with characteristics, and then consistency analysis and difference analysis are performed on it, and the data that does not meet or is abnormal in the braking curve is eliminated, so that the retained braking curve has good performance, and then the stage characteristics of the braking curve are extracted, and the time domain analysis and equivalent trapezoidal transformation are performed to simplify each braking stage, and the simplified braking curves are connected to obtain a simplified diagram of the braking curve characteristics when the vehicle collides.

[0039] Therefore, compared with the traditional curve simplification algorithm, the present application can classify and simplify the braking curve according to the characteristic factors, and effectively solve the problem that the existing curve simplification method cannot retain the curve characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flowchart of an embodiment of the present invention;

[0041] Figure 2 This is a simplified model diagram of a braking curve according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following is further described in detail through specific implementation methods:

[0043] The embodiment is basically as shown in the attached Figure 1 As shown: A simplified analysis and processing method for AEB braking curve characteristics, comprising:

[0044] S1: Obtain the braking curve of the vehicle collision; S1 includes:

[0045] S1-1: The vehicle longitudinal deceleration is greater than 0.5m / s 2 AEB is activated at 0.5m / s 2 The braking curve is aligned with the reference moment, and the braking curve data 1 second before and after AEB activation are obtained;

[0046] S1-2: Filter the acquired braking curve data to obtain a processed braking curve.

[0047] In this embodiment, according to the relevant provisions of the AEB function evaluation in the C-IASI 2020 version, when the longitudinal deceleration of the vehicle reaches 0.5m / s 2 If the speed is higher than 0.5 m / s, AEB is considered to be activated. 2The braking curve is aligned with the time as the benchmark, and the braking curve data 1 second before and after AEB activation are obtained; at the same time, the obtained braking curve data is filtered by a 6Hz second-order Butterworth zero-phase low-pass filter, and after eliminating interference such as mutations and noise, multiple braking curves that are smoother and more characteristic than the original braking curves can be obtained.

[0048] S2: Perform consistency analysis and difference analysis on the acquired braking curve, and extract the braking strategy, braking intensity and time factors in the waveform of the braking curve; S2 includes:

[0049] S2-1: Take the average of multiple braking curves of the same vehicle model under the same emergency braking condition according to the time points, fit the average values ​​at the corresponding time points into a curve, and generate a mean fitting curve;

[0050] S2-2: Draw the braking curves of different models on the same graph according to the time points and remove abnormal curves;

[0051] S2-3: After the consistency analysis of S2-1 and the difference analysis of S2-2, the braking strategy, braking intensity and time factors to reach steady state are extracted according to the trend of the braking curve waveform.

[0052] In S2-1, the average of multiple braking curves of the same vehicle model under the same emergency braking condition is taken according to the time point, and the average at the corresponding time point is fitted into a curve to generate a mean fitting curve, and the correlation between all braking curves of the vehicle and the mean fitting curve is analyzed according to the ISO-18571 standard.

[0053] In S2-2, the braking curves of different models are plotted on the same graph according to the time points, and abnormal curves are eliminated, such as curves with different braking strategies and sudden changes in acceleration values. After the braking curves are processed by S2-1 and S2-2, it is convenient for subsequent feature extraction.

[0054] S3: construct a simplified model of the braking curve, use the extracted braking strategy, braking intensity and time factors as input data of the simplified model of the braking curve, and output a stage characteristic diagram of the braking curve; S3 includes:

[0055] S3-1: constructing a simplified braking curve model, wherein the simplified braking curve model is a time-acceleration coordinate model;

[0056] S3-2: The extracted braking strategy, braking intensity and time factors are used as input data of the simplified braking curve model, and a braking curve stage characteristic diagram is output. The braking curve stage characteristics include an action stage, a braking hold stage and a braking release stage, and each braking curve stage characteristic corresponds to a braking intensity performance and a time performance.

[0057] In this embodiment, if Figure 2 As shown in the figure, the simplified model diagram of the braking curve is constructed, where the horizontal axis is time and the vertical axis is acceleration, which is used to characterize the braking curve generated by the vehicle AEB braking. According to the vehicle's braking strategy, the change of braking intensity and time factors, the braking curve is divided into the following Figure 2 The three braking curve stage characteristics shown are: ab segment represents the effective stage, that is, the deceleration change when the vehicle starts braking, bc segment is the braking holding stage, and cd segment is the braking release stage. The braking intensity of each of the above stages is characterized by the acceleration on the vertical axis, and the time is characterized by the horizontal axis.

[0058] S4: Analyze the linear change of the braking curve in each braking curve stage characteristic diagram, generate the braking simplified curve of each braking curve stage, and connect the braking simplified curves of each braking curve stage to generate the simplified characteristic curve of the entire braking curve stage. S4 includes:

[0059] S4-1: Perform time domain analysis on the braking curve stage characteristic diagram in the simplified braking curve model, and calculate the speed at each moment according to the acceleration curve in the time domain. The calculation formula is:

[0060]

[0061] Among them, v n represents the speed at time n, t n represents the time n, a represents the acceleration;

[0062] S4-2: The area enclosed by the braking curve and the time axis in each braking curve stage characteristic diagram is represented as the speed change of the vehicle during braking, the speed change of the braking curve in each braking curve stage diagram is obtained, and converted into a linear change using the equivalent trapezoidal method; specifically:

[0063] The definition is that the action phase is the ab segment in the braking curve phase characteristic diagram, the brake holding phase is the bc segment in the braking curve phase characteristic diagram, and the brake release phase is the cd segment in the braking curve phase characteristic diagram;

[0064] When the observed value of the speed change is the same as the calculated value of the waveform of the braking curve, the waveform of the braking holding stage is equivalent to a constant, and the calculation formula is:

[0065]

[0066] Where, ΔV b-c It represents the speed change in the simplified model of the braking curve during the braking holding phase. represents the velocity at point c, represents the speed at point b;

[0067] The effective stage is equivalent to a linear change, and the calculation formula is:

[0068]

[0069] Among them, a represents the acceleration of segment bc, and k1 represents the slope of the acceleration of segment ab;

[0070] The brake release phase is equivalent to a linear change, and the calculation formula is:

[0071]

[0072] Among them, k2 represents the slope of the acceleration in the cd segment, and t3 represents the time at point d.

[0073] S4-3: Connect the braking curves represented by the linear variation of each braking curve stage characteristic to generate a simplified braking curve diagram.

[0074] In this embodiment, if Figure 2 The simplified process diagram of the braking curve shown in the figure, a is the moment when the braking peak value reaches 5% for the first time, the dividing points are the starting time t1 of the braking hold phase (the moment when the acceleration is higher than 85% of the peak value for the first time) and the ending time t2 of the braking hold phase (the moment when the acceleration is higher than 85% of the peak value for the last time) and the moment t3 when the acceleration is 0 in the braking release phase; therefore, the braking stage characteristics can also be divided according to the dividing points.

[0075] After the braking stage characteristics are divided, the analysis is carried out in the time domain. According to the acceleration curve in the time domain, the speed at each moment can be calculated. Therefore, the area enclosed by the braking curve and the time axis in a certain period of time is the speed change of the vehicle during the braking process. When the observed value of the speed change is equal to the calculated value of the equivalent waveform, the waveform of the braking holding stage can be equivalent to a constant, and the action stage and the brake release stage can also be equivalent to a linear change. The linear change is displayed as a simplified curve in the simplified model diagram of the braking curve, as shown in the figure below: Figure 2 By connecting the linear change curves of each stage, we can get the simplified characteristic curve diagram of the braking curve.

[0076] In summary, compared with the traditional brake curve simplification algorithm, the method of classifying and simplifying according to relevant factors in the present application can effectively solve the problem that the existing curve simplification method cannot retain the curve characteristics.

[0077] Therefore, the simplified method of the present invention is concise and efficient, and can better preserve the meaning of the corresponding time nodes. Even scholars who are not familiar with the algorithm can quickly understand its principle and use it.

[0078] The above are only embodiments of the present invention. Common knowledge such as the known specific structures and characteristics in the scheme is not described in detail here. Ordinary technicians in the relevant field know all the common technical knowledge in the technical field to which the invention belongs before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply conventional experimental means before that date. Ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A simplified analysis and processing method for AEB braking curve characteristics, characterized by: include: S1: Obtain the braking curve of vehicle collision; S2: Perform consistency analysis and difference analysis on the acquired braking curve to extract the braking strategy, braking intensity and time factors in the waveform of the braking curve; S3: constructing a simplified braking curve model, taking the extracted braking strategy, braking intensity and time factors as input data of the simplified braking curve model, and outputting a braking curve stage characteristic diagram; the braking curve stage characteristics in the braking curve stage characteristic diagram include an action stage, a braking holding stage and a braking release stage, and each braking curve stage characteristic corresponds to a braking intensity performance and a time performance; S4: Analyze the linear change of the braking curve in each braking curve stage characteristic diagram, generate a simplified braking curve for each braking curve stage, and connect the simplified braking curves for each braking curve stage to generate a simplified characteristic curve for the entire braking curve stage; S4 includes: S4-1: Perform time domain analysis on the braking curve stage characteristic diagram in the simplified braking curve model, and calculate the speed at each moment according to the acceleration curve in the time domain. The calculation formula is: Among them, v n represents the speed at time n, t n represents the time n, a represents the acceleration; S4-2: The area enclosed by the braking curve and the time axis in each braking curve stage characteristic diagram is represented as the speed change of the vehicle during the braking process, the speed change of the braking curve in each braking curve stage diagram is obtained, and converted into a linear change using an equivalent trapezoidal method; S4-3: connecting the braking curves represented by the linear variation of each braking curve stage characteristic to generate a simplified braking curve diagram; The S4-2 is specifically: The definition is that the action phase is the ab segment in the braking curve phase characteristic diagram, the brake holding phase is the bc segment in the braking curve phase characteristic diagram, and the brake release phase is the cd segment in the braking curve phase characteristic diagram; When the observed value of the speed change is the same as the calculated value of the waveform of the braking curve, the waveform of the braking holding stage is equivalent to a constant, and the calculation formula is: Where, ΔV b-c It represents the speed change in the simplified model of the braking curve during the braking holding phase. represents the velocity at point c, represents the speed at point b; The effective stage is equivalent to a linear change, and the calculation formula is: Among them, a represents the acceleration of segment bc, and k1 represents the slope of the acceleration of segment ab; The brake release phase is equivalent to a linear change, and the calculation formula is: Among them, k2 represents the slope of the acceleration in the cd segment, and t3 represents the time at point d.

2. The simplified analysis and processing method for AEB braking curve characteristics according to claim 1, characterized in that: The S1 includes: S1-1: The vehicle longitudinal deceleration is greater than 0.5m / s 2 AEB is activated at 0.5m / s 2 The braking curve is aligned with the reference moment, and the braking curve data 1 second before and after AEB activation are obtained; S1-2: Filter the acquired braking curve data to obtain a processed braking curve.

3. The simplified analysis and processing method for AEB braking curve characteristics according to claim 2 is characterized in that: The S2 includes: S2-1: Take the average of multiple braking curves of the same vehicle model under the same emergency braking condition according to the time points, fit the average values ​​at the corresponding time points into a curve, and generate a mean fitting curve; S2-2: Draw the braking curves of different models on the same graph according to the time points and remove abnormal curves; S2-3: After the consistency analysis of S2-1 and the difference analysis of S2-2, the braking strategy, braking intensity and time factors to reach steady state are extracted according to the trend of the braking curve waveform.

4. The simplified analysis and processing method for AEB braking curve characteristics according to claim 3 is characterized in that: The S3 includes: S3-1: constructing a simplified braking curve model, wherein the simplified braking curve model is a time-acceleration coordinate model; S3-2: The extracted braking strategy, braking intensity and time factors are used as input data of the simplified model of the braking curve, and a braking curve stage characteristic diagram is output.

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