Comfortable braking cooperative control method capable of preventing slope sliding

Abstract

The invention discloses a comfortable braking cooperative control method capable of preventing slope sliding, which comprises the following steps of: firstly, preliminarily obtaining information of a slope where a vehicle is located, and then synchronously carrying out related compensation of a slope difference value and compensation of a vehicle attitude; and the minimum target deceleration required for preventing the vehicle from sliding on the slope and the damping force required for restraining pitching motion in the vehicle braking process are calculated, and the comfortable braking grade is selected. In the whole process, the ramp acceleration of the vehicle needs to be calculated in real time to obtain compensation, longitudinal and vertical control strategies are used for cooperative control, a brake-by-wire product is utilized, a non-adhesion coefficient is analyzed, braking force is distributed, load transfer is weakened through rear braking force during ramp parking, the pitching characteristic of the vehicle can be weakened under the non-emergency working condition, and the vehicle safety is improved. And the riding comfort of a driver and passengers is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of brake product line control, and more particularly to a comfortable brake cooperative control method capable of preventing hill rolling. BACKGROUND

[0002] The development of line control chassis and intelligent driving technology has a high correlation. With the continuous development of automatic driving technology, line control chassis products have been increasingly applied in the whole vehicle. Line control brake product is one of the important modules. Recently, the research on vehicle braking technology is very active, and the research mainly focuses on safety and braking efficiency, and the research on user experience is relatively less. The user experience of automatic driving vehicles will directly affect the acceptance and trust of users for automatic driving vehicles, and even will affect the popularization of automatic driving vehicles.

[0003] In the system setting of the online brake product, from the safety point of view, when the vehicle is in an emergency working condition, the line control brake system will distribute the brake force according to the adhesion coefficient to minimize the braking distance, but in the daily commuting in the city, most cases are not in the emergency working condition, if the brake force is still distributed according to the adhesion coefficient, the pitching characteristics caused by braking cannot be effectively weakened, the vehicle running stability is affected, and the vehicle experience of the driver and the passenger cannot be effectively improved.

[0004] As disclosed in Chinese patent application publication No. 202410701289.3, a comfortable brake method is disclosed, which dynamically and real-timely updates the braking distance target through the sensing information in front of the vehicle, so as to dynamically update the activation speed of the comfortable brake mode according to the updated braking distance target, so as to enter the comfortable brake mode to reduce the brake force when the speed is reached, thereby reducing the brake force mutation in the vehicle braking process. Although the scheme can adjust the brake intensity according to the distance from the front vehicle, the driver's comfort can be increased as much as possible without rear-end collision, but the possibility of vehicle sliding caused by reduction of brake force on the slope is not considered.

[0005] The prior art scheme solves the above problems while ensuring the driving comfort, but does not consider the measures to prevent the vehicle from sliding. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a comfortable brake cooperative control method capable of preventing hill rolling, which considers the slope of the vehicle in the comfortable brake process, prevents the vehicle from rolling down the hill in the hill brake working condition by real-time evaluation of the hill acceleration of the vehicle, and suppresses the vehicle pitch angle during braking by using a continuously adjustable damping shock absorber, so as to realize longitudinal and vertical cooperative control and improve the safety and comfort of the driver.

[0007] To achieve the above object, the present application provides the following technical solutions:

[0008] A comfortable braking cooperative control method capable of preventing coasting down a slope, comprising

[0009] S1, activated by a braking instruction, automatically collecting current vehicle key signals, and preliminarily calculating a slope where the vehicle is located;

[0010] S2, further processing the slope where the vehicle is located obtained in step S1, and obtaining a fixed number n of ramp acceleration signal sampling points in a fixed time period at a fixed time interval;

[0011] When the comfortable braking function is started, the slope difference between the front and rear time is calculated;

[0012] S3, judging the vehicle working condition according to the positive and negative conditions of the sampling points obtained in step S2, and selecting different levels of slope compensation values according to the size of the slope difference between the front and rear time calculated;

[0013] According to the calculation result of step S1, the current slope difference is taken as the corresponding compensation amount, and the compensated ramp acceleration is calculated;

[0014] S4, calculating the longitudinal deceleration required for the vehicle to brake according to the current vehicle longitudinal driving force;

[0015] Referring to the compensated ramp acceleration calculated in step S3, the minimum target deceleration for braking the vehicle is further calculated;

[0016] S5, identifying the brake instruction, collecting the pitch angle and pitch angle velocity information by the IMU, and changing the damping force by the pitch compensation fuzzy controller through the CDC damper to suppress the vehicle pitch motion;

[0017] S6, selecting the final output CST level according to the minimum target deceleration calculated in step S4 combined with the current pitch angle information, and braking.

[0018] Further, the calculation formula of the slope where the vehicle is located in step S1 is

[0019] ax_rampR=ax_veh-ax_sens-dPsi*vyVeh;

[0020] In the calculation formula of step S1, ax_rampR is the uncompensated ramp acceleration, ax_veh is the vehicle longitudinal acceleration, ax_sens is the vehicle horizontal direction longitudinal acceleration, dPsi is the yaw rate, and vyVeh is the vehicle lateral velocity.

[0021] Further, the time period is T, the time interval is t seconds, and the ramp acceleration signals ax_rampR of n sampling points collected in step S2 are S1, S2, …, Sn respectively. n ;

[0022] When the comfort braking function is started, the slope difference between the current time and the last time is calculated by the following formula

[0023] ramp_change = S i -S i-1 ;

[0024] In the formula, ramp_change is the ramp acceleration change at the current time, S i is the ramp acceleration at the current time, and S i-1 is the ramp acceleration at the last time.

[0025] Further, in step S3, it is necessary to determine whether the vehicle is in uphill, downhill or uphill and downhill working conditions.

[0026] The slope compensation values of different levels are comp1, comp2, …, comp n ;

[0027] The calculation formula of the compensated ramp acceleration is

[0028] ax_ramp = ax_rampR + comp i ;

[0029] In the formula, ax_ramp is the compensated ramp acceleration.

[0030] Further, in step S4, the longitudinal deceleration required for the vehicle to brake is the ratio of the longitudinal deceleration force to the mass of the vehicle.

[0031] The calculation formula of the minimum target deceleration for the vehicle to brake is

[0032] axTarMin = -abs(ax_accel-ax_ramp);

[0033] In the formula, axTarMin is the minimum target deceleration for the vehicle to brake, and ax_accel is the longitudinal deceleration required for the vehicle to brake.

[0034] Further, in step S5, the driver's brake command is identified through the pedal signal and vehicle speed information, the IMU collects the pitch angle and pitch angle velocity information, and the CDC shock absorber is used to limit the pitch angle generated during the vehicle braking process from the vertical control angle.

[0035] Further, the pitch compensation fuzzy controller in step S5 takes the pitch angle and the pitch angle velocity as inputs, and calculates the pitch compensation moment, and the calculation formula is

[0036] M θ =ι f cosθ(F b1 +F b2 )-ι r cosθ(F b3 +F b4 )

[0037] In the calculation formula, M θ is the moment output by the pitch compensation fuzzy controller, and F bn (n=1, 2, 3, 4) is the compensation damping force fed back to the vehicle.

[0038] Further, the final output CST level in step S6 is L1, L2, ……L n , and each comfort braking level contains the corresponding braking parameters, the comfort braking level CST_L1 contains the corresponding braking parameters m 11 , m 12 , m 13 ……m 1m , the comfort braking level CST_L2 contains the corresponding braking parameters m 21 , m 22 , m 23 ……m 2m , and the comfort braking level CST_L n contains the corresponding braking parameters m n1 , m n2 , m n3 ……m nm .

[0039] Further, the processes of steps S1-S4 and step S5 are performed cooperatively.

[0040] Further, the control rule table of the pitch compensation fuzzy controller in the whole control method is

[0041] In step S3, the vehicle working condition is judged according to the above control rule.

[0042] In summary, the present application has the following beneficial effects: the vehicle slope sliding phenomenon in the slope braking working condition is prevented by evaluating the slope acceleration of the vehicle in real time, and the pitch angle of the vehicle during braking is suppressed by using the adjustable damping shock absorber; the safety and comfort of the driver during driving are improved through the cooperative control of the longitudinal and vertical directions, the driving comfort is ensured, and the vehicle slope sliding is effectively prevented. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 Flow chart of the control method according to an embodiment of the present application. DETAILED DESCRIPTION

[0044] Embodiment:

[0045] The application will be further described below with reference to the accompanying drawings. Figure 1 The application will be further described below with reference to the accompanying drawings.

[0046] A comfortable braking cooperative control method for preventing hill coasting, as shown in the flow chart as follows: Figure 1

[0047] S1, activated after receiving the driver's braking instruction, automatically collects data, and calculates the slope where the vehicle is located according to the signals of the longitudinal acceleration of the current vehicle, the longitudinal acceleration in the horizontal direction, the yaw rate and the lateral speed of the vehicle, etc. The calculation formula of the slope where the vehicle is located is

[0048] ax_rampR = ax_veh - ax_sens - dPsi * vyVeh;

[0049] In the calculation formula, ax_rampR is the ramp acceleration without compensation, with the unit of m / s 2 , ax_veh is the longitudinal acceleration of the vehicle, with the unit of m / s 2 , ax_sens is the longitudinal acceleration of the vehicle in the horizontal direction, with the unit of m / s 2 , dPsi is the yaw rate, with the unit of rad / s, and vyVeh is the lateral speed of the vehicle, with the unit of m / s.

[0050] S2, further process the slope where the vehicle is located obtained in step S1, obtain a fixed number n of ramp acceleration signal sampling points in a fixed time period at a fixed time interval, the time period is T, the time interval is t seconds, and the ramp acceleration signals of n sampling points are S1, S2, …, Sn respectively. n ;

[0051] When the comfortable braking function is started, the slope difference between the current time and the previous time is calculated, and the slope difference calculation formula between the current time and the previous time is

[0052] ramp_change = S i -S i-1 ;

[0053] In the calculation formula, ramp_change is the change of the ramp acceleration at the current time, with the unit of m / s 2 , and S i is the ramp acceleration at the current time, with the unit of m / s​2 , S i-1 is the ramp acceleration of the last time, unit: m / s 2 .

[0054] S3, the positive and negative cases of the n sampling points obtained according to step S2, combined with the control rule table of the pitch compensation fuzzy controller to judge the vehicle working condition, it is needed to judge whether the vehicle is in uphill, downhill or uphill and downhill working condition, and according to the slope difference value obtained in step S2, the slope compensation values comp1, comp2, …, comp n are selected in different grades, and finally according to the calculation result of step S1, the current slope difference value is taken as the corresponding compensation amount, the compensated ramp acceleration is calculated, and the calculation formula of the compensated ramp acceleration is

[0055] ax_ramp = ax_rampR + comp i ;

[0056] In the calculation formula, ax_ramp is the compensated ramp acceleration, unit: m / s 2 , ax_rampR is the uncompensated ramp acceleration, unit: m / s 2 .

[0057] S4, according to the current vehicle longitudinal driving force, the longitudinal deceleration required for the vehicle to brake is calculated, and the longitudinal deceleration required for the vehicle to brake is the ratio of the longitudinal deceleration force to the mass of the vehicle;

[0058] According to the compensated ramp acceleration calculated in step S3, the minimum target deceleration for the vehicle to brake is further calculated, and the calculation formula of the minimum target deceleration for the vehicle to brake is

[0059] axTarMin = -abs(ax_accel-ax_ramp);

[0060] In the calculation formula, axTarMin is the minimum target deceleration for the vehicle to brake, ax_accel is the longitudinal deceleration required for the vehicle to brake, ax_ramp is the compensated ramp acceleration, unit: m / s 2 .

[0061] S5, the driver's brake instruction is identified through the pedal signal, vehicle speed and other information, the IMU collects the pitch angle and pitch angle velocity and other information, the CDC shock absorber is used to limit the pitch angle generated in the vehicle braking process from the vertical control angle, the pitch compensation fuzzy controller takes the pitch angle and pitch angle velocity as the input, and changes the damping force through the CDC shock absorber to suppress the pitch motion of the vehicle, and the calculation formula is

[0062] M θ =f cosθ(F b1 +F b2 )-ι r cosθ(F b3 +F b4 )

[0063] In the calculation formula, M θ is the moment of the pitch compensation fuzzy controller output, F bn (n = 1, 2, 3, 4) is the compensation damping force fed back to the vehicle.

[0064] S6, according to the minimum target deceleration axTarMin calculated in step S4, and the current pitch angle and other information, select the final output CST level L1, L2, … L n Each comfort braking level contains the corresponding braking parameters, and the comfort braking level CST_L1 contains the corresponding braking parameters m 11 , m 12 , m 13 … m 1m , the comfort braking level CST_L2 contains the corresponding braking parameters m 21 , m 22 , m 23 … m 2m , … the comfort braking level CST_L n contains the corresponding braking parameters m n1 , m n2 , m n3 … m nm， braking.

[0065] Wherein, the process of step S1 to step S4 and step S5 is carried out in coordination, the control rule of the pitch compensation fuzzy controller in the whole control method is shown in the following table:

[0066] Control rule table of pitch compensation fuzzy controller

[0067]

[0068] The control method provided in the application uses a linear control braking product to distribute the braking force by analyzing the non-adhesion coefficient, to weaken the load transfer of the vehicle during braking through the rear braking force when parking, to weaken the pitch characteristics of the vehicle under non-emergency working conditions, to study the real-time calculation method of vehicle ramp acceleration, to cooperatively control the longitudinal and vertical control strategies, to improve the riding comfort of the driver and passengers, and to effectively prevent the vehicle from sliding on the slope.

[0069] It should be noted that the specific embodiments are only to explain the present application, and are not to limit the present application, and the person skilled in the art can make the modification of the present embodiments without the creative contribution according to the need after reading the present specification, but as long as in the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A comfortable braking coordinated control method for preventing slope runaway, characterized in that: include S1. Activated by braking command, it automatically collects key signals of the current vehicle and preliminarily calculates the slope of the vehicle. S2. Further process the slope of the vehicle obtained in step S1, and obtain a fixed number of n slope acceleration signal sampling points within a fixed time period at fixed time intervals. When the comfort braking function is activated, the slope difference between the preceding and following moments is calculated; S3. Determine the vehicle's operating condition based on the positive or negative status of the sampling points obtained in step S2, and select different levels of slope compensation values ​​based on the calculated difference in slope between the previous and next times. Based on the calculation results of step S1, the current slope difference is used as the corresponding compensation amount to calculate the compensated slope acceleration. S4. Calculate the longitudinal deceleration required to bring the vehicle to braking based on the current longitudinal driving force of the vehicle. Referring to the compensated ramp acceleration calculated in step S3, further calculate the minimum target deceleration that will brake the vehicle. S5. Recognize the braking command. The IMU collects pitch angle and pitch velocity information. The pitch compensation fuzzy controller changes the damping force through the CDC damper to suppress the vehicle's pitch motion. S6. Based on the minimum target deceleration calculated in step S4, and combined with the current pitch angle information, select the final output CST level and perform braking.

2. The comfortable braking coordinated control method for preventing runaway as described in claim 1, characterized in that: The formula for calculating the slope at the vehicle lock in step S1 is as follows: ax_rampR=ax_veh-ax_sens-dPsi*vyVeh; In the calculation formula of step S1, ax_rampR is the uncompensated ramp acceleration, ax_veh is the vehicle longitudinal acceleration, ax_sens is the vehicle's longitudinal acceleration in the horizontal direction, dPsi is the yaw rate, and vyVeh is the vehicle's lateral velocity.

3. The comfortable braking coordinated control method for preventing runaway as described in claim 2, characterized in that: In step S2, the time period is T, the time interval is t seconds, and the slope acceleration signals ax_rampR of n sampling points are collected, namely S1, S2, ... S n ; When comfort braking is activated, the formula for calculating the slope difference between the current and previous moments is as follows: ramp_change=S i -S i-1 ; In this calculation formula, ramp_change represents the change in ramp acceleration at the current moment, S i Let S be the acceleration of the slope at the current moment. i-1 This represents the ramp acceleration at the previous moment.

4. The comfortable braking coordinated control method for preventing landslides according to claim 3, characterized in that: In step S3, it is necessary to determine whether the vehicle is in an uphill, downhill, or alternating uphill and downhill condition. The slope compensation values ​​for different levels are comp1, comp2, ... comp. n ; The formula for calculating the compensated ramp acceleration is as follows: ax_ramp=ax_rampR+comp i ; In this calculation formula, ax_ramp is the ramp acceleration obtained after compensation.

5. The comfortable braking coordinated control method for preventing runaway as described in claim 4, characterized in that: In step S4, the longitudinal deceleration required to brake the vehicle is the ratio of the longitudinal deceleration force to the vehicle mass. The formula for calculating the minimum target deceleration required for vehicle braking is: axTarMin=-abs(ax_accel-ax_ramp); In this calculation formula, axTarMin is the minimum target deceleration required to brake the vehicle, and ax_accel is the lateral deceleration required for the vehicle to brake.

6. The comfortable braking coordinated control method for preventing landslides according to claim 5, characterized in that: In step S5, the driver's braking command is identified through pedal signal and vehicle speed information. The IMU collects pitch angle and pitch speed information, and the CDC damper limits the pitch angle generated during vehicle braking from the perspective of vertical control.

7. The comfortable braking coordinated control method for preventing runaway as described in claim 5, characterized in that: In step S5, the pitch compensation fuzzy controller uses the pitch angle and pitch angular velocity as inputs to calculate the pitch compensation torque. The calculation formula is as follows: M θ =i f cosθ(F b1 +F b2 )-i r cosθ(F b3 +F b4 ) In this calculation formula, M θ To compensate for the torque output of the fuzzy controller, F bn (n = 1, 2, 3, 4) represents the compensating damping force fed back to the vehicle.

8. The comfortable braking coordinated control method for preventing landslides according to claim 1, characterized in that: The final CST levels output in step S6 are L1, L2, ... L n Each comfort braking level includes corresponding braking parameters. For example, comfort braking level CST_L1 includes the corresponding braking parameter m. 11 m 12 m 13 ...m 1m The comfort braking level CST_L2 includes the corresponding braking parameters m 21 m 22 m 23 ...m 2m ...Comfort braking level CST_L n Includes the corresponding braking parameter m n1 m n2 m n3 ...m nm .

9. The comfortable braking coordinated control method for preventing runaway as described in claim 1, characterized in that: Steps S1 to S4 and step S5 are performed in a coordinated manner.

10. The comfortable braking coordinated control method for preventing runaway as described in claim 1, characterized in that: The control rule table for the pitch compensation fuzzy controller in the entire control method is as follows: In step S3, the vehicle operating condition is determined according to the above control rules.

Images