Vehicle braking smoothness control method and device

Abstract

The invention relates to a vehicle braking smoothness control method and device, and the method comprises the steps: collecting the SOC information of a battery management system, judging whether a battery allows energy recovery or not, and obtaining a first flag bit; whether the vehicle is in a wheel locking state or not is judged by collecting the vehicle speed and the wheel speed, and a second flag bit is obtained; judging whether the vehicle is in an emergency braking working mode or not by collecting the travel change rate of a brake pedal to obtain a third flag bit; the steering angle of a vehicle steering wheel is obtained, whether the vehicle is in a right steering state or not is judged, logical operation is conducted on all obtained zone bits, and whether a chassis controller sends an energy recovery enabling signal to a motor controller or not is judged according to the operation result for enabling; by collecting different types of steering information, obtaining corresponding flag bits and carrying out logical operation, accurate recognition of vehicle emergency braking can be achieved, and energy recovery entering is avoided during steering state braking.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle chassis control, and particularly to a vehicle braking smoothness control method and a control device. Background Art

[0002] Service braking, as an important safety item of an automobile, is directly related to driving safety and the life safety of the driver. On the basis of ensuring braking safety, users have higher and higher requirements for braking comfort. Since a pure electric vehicle will actively activate the energy recovery function during braking to shorten the vehicle braking distance, however, during emergency braking, the wheels will lock up. At this time, the energy recovery function will actively withdraw, resulting in a sudden decrease in the braking force, and the vehicle body will suddenly lean forward due to inertia, causing the driver to bump into the steering wheel, and the driving experience is relatively poor. Summary of the Invention

[0003] The purpose of the present invention is to provide a vehicle braking smoothness control method and a control device in view of the deficiencies of the prior art.

[0004] The present invention is implemented by adopting the following technical solutions:

[0005] A vehicle braking smoothness control method includes:

[0006] By collecting the SOC information of the battery management system BMS, it is judged whether the battery allows energy recovery, and a first flag bit is obtained;

[0007] By collecting the vehicle speed and the wheel speed, it is judged whether the vehicle is in a wheel lock-up state, and a second flag bit is obtained;

[0008] By collecting the change rate of the brake pedal stroke, it is judged whether the vehicle is in an emergency braking working mode, and a third flag bit is obtained;

[0009] By obtaining the steering angle of the vehicle steering wheel through the angle signal collected by the vehicle angle sensor, it is judged whether the vehicle is in a right-turning state, and a fourth flag bit is obtained;

[0010] The first flag bit, the second flag bit, the third flag bit and the fourth flag bit are subjected to a logical operation to obtain an operation result. According to the value of the operation result, it is judged whether to send an energy recovery enable signal to the motor controller MCU for enabling.

[0011] Preferably, the wheel speed includes the left front wheel speed, the right front wheel speed, the left rear wheel speed and the right rear wheel speed.

[0012] Preferably, the strategy for determining whether to send an energy recovery enabling signal to the motor controller MCU for enabling is as follows: if the value of the operation result is equal to 1, the chassis controller sends an energy recovery enabling signal to the motor controller MCU; if the value of the operation result is equal to 0, the chassis controller sends a signal to prohibit the energy recovery enabling signal to the motor controller MCU.

[0013] Preferably, the determination of whether the battery allows energy recovery is as follows;

[0014] If the SOC information of the battery management system is within the SOC threshold range required for judging energy recovery, it is determined that the battery meets the energy recovery state, and the first flag bit is 1; otherwise, it means that the battery does not meet the energy recovery state, and the first flag bit is 0.

[0015] Preferably, the determination of whether the vehicle is in a wheel locked state is as follows:

[0016] Compare the vehicle speed with the speeds of the left front wheel, right front wheel, left rear wheel, and right rear wheel, and compare the difference between the vehicle speed and the vehicle speed converted from the speeds of the left front wheel, right front wheel, left rear wheel, and right rear wheel. If it is greater than the specified value within n consecutive cycles, it is determined that a certain wheel of the vehicle is in a locked state, and the second flag bit is 0; otherwise, it means that the vehicle is not in a locked state, and the second flag bit is 1, where the specified value is a calibrated value.

[0017] Preferably, the determination of whether the vehicle is in an emergency braking working mode is as follows: if the change rate of the brake pedal stroke is within the range of the change rate of the brake pedal stroke required for judging an emergency brake, it is determined that the vehicle is in an emergency braking state, and the third flag bit is 0; otherwise, it means that the vehicle is in an emergency braking state, and the third flag bit is 1.

[0018] Preferably, the determination of whether the vehicle is in a turning state is as follows: if the steering angle of the vehicle's steering wheel is within the angle threshold range for judging turning, it means that the vehicle is in a turning state, and the fourth flag bit is 0; otherwise, it means that the vehicle is not in a turning state, and the fourth flag bit is 1.

[0019] Preferably, it further includes judging the working gear of energy recovery by comparing the magnitude of the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor, and the chassis controller sends an energy recovery working gear signal to the motor controller MCU;

[0020] The method for judging the working gear of energy recovery is as follows:

[0021] Compare the vehicle speed converted from the wheel speed with the vehicle speed collected by the vehicle speed sensor. If the difference V is larger, the gear of energy recovery is lower, where the steering threshold is calibrated according to the tire radius parameter;

[0022] The steering thresholds include a first threshold Φ1, a second threshold Φ2, and a third threshold Φ3, and Φ3 > Φ2 > Φ1;

[0023] If the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor is within the first threshold Φ1, the motor energy recovery is at the maximum gear; if the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor is within the second threshold Φ2, the motor energy recovery is at the intermediate gear; if the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor is within the third threshold Φ3, the motor energy recovery is at the lowest gear; if the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor is greater than the third threshold Φ3, the motor energy recovery is actively turned off.

[0024] A vehicle braking smoothness control device for implementing the vehicle braking smoothness control method described above, including a chassis controller, which is integrated with:

[0025] An acquisition module for acquiring the wheel speed collected by the wheel speed sensor; for acquiring the vehicle speed signal collected by the vehicle speed sensor; for acquiring the angle signal collected by the steering angle sensor of the vehicle steering wheel; for acquiring the brake pedal stroke change rate signal collected by the brake pedal sensor; for acquiring the SOC information collected by the battery management system BMS;

[0026] A judgment module for judging whether the vehicle is in a state that satisfies the energy recovery working condition and the working gear of the energy recovery;

[0027] A control module for obtaining the judgment result of the judgment module, performing logical operations, and controlling whether to send an energy recovery enable signal and a working gear signal to the motor controller MCU according to the logical operation result, for energy recovery and power adjustment;

[0028] The wheel speed sensor, the vehicle speed sensor, the steering angle sensor, and the brake pedal sensor are all connected to the chassis controller; the chassis controller, the motor controller MCU, and the battery management system BMS are all connected to the vehicle CAN network.

[0029] Preferably, the wheel speed sensor includes a left front wheel speed sensor, a right front wheel speed sensor, a left rear wheel speed sensor, and a right rear wheel speed sensor.

[0030] Compared with the prior art, the present invention has the following beneficial technical effects:

[0031] The present invention can accurately identify the emergency braking and steering state braking of a vehicle by collecting four different types of steering information, obtaining the corresponding flag bits, and performing logical operations, so as to avoid the entry of energy recovery; when there is a continuous difference between the left and right wheel speeds of the vehicle and the vehicle speed, it can accurately identify the braking state of the vehicle, actively adjust the magnitude of the energy recovery power, avoid sudden withdrawal of energy recovery and reduction of braking force due to frequent wheel locking, resulting in loss of vehicle balance, and improve the driving and riding experience of the driver and passengers. Description of the Drawings

[0032] Figure 1 It is the architecture diagram of the control method in the present invention;

[0033] Figure 2 It is the schematic diagram of energy recovery gear control in the present invention;

[0034] Figure 3 It is the architecture diagram of the control device in the present invention. Detailed Embodiments

[0035] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] As Figure 1 shown, a vehicle braking smoothness control method includes:

[0037] By collecting the SOC information of the battery management system BMS, determine whether the battery allows energy recovery to obtain the first flag bit;

[0038] By collecting the vehicle speed and wheel speed, determine whether the vehicle is in a wheel locking state to obtain the second flag bit;

[0039] By collecting the change rate of the brake pedal stroke, determine whether the vehicle is in an emergency braking working mode to obtain the third flag bit;

[0040] Obtain the steering angle of the vehicle steering wheel through the angle signal collected by the vehicle angle sensor, and determine whether the vehicle is in a right-turning state to obtain the fourth flag bit;

[0041] Perform logical operations on the first flag bit, the second flag bit, the third flag bit, and the fourth flag bit to obtain an operation result, and according to the value of the operation result, determine whether to send an energy recovery enable signal to the motor controller MCU for enabling.

[0042] The wheel speeds include the left front wheel speed, the right front wheel speed, the left rear wheel speed, and the right rear wheel speed.

[0043] Among them, the SOC information and the steering angle information in the battery management system BMS are sent in the form of CAN messages; the vehicle speed and wheel speed information are sent as pulse signals; the brake pedal information is sent in the form of voltage signals.

[0044] Determine whether to send an energy recovery enable signal to the motor controller MCU. The enabling strategy is as follows: if the value of the operation result is equal to 1, the chassis controller sends an energy recovery enable signal to the motor controller MCU; if the value of the operation result is equal to 0, the chassis controller sends a signal to prohibit the energy recovery enable signal to the motor controller MCU.

[0045] Determine whether the battery allows energy recovery as;

[0046] If the SOC information of the battery management system BMS is within the SOC threshold range required for judging energy recovery, it is determined that the battery meets the energy recovery state, and the first flag bit is 1; otherwise, it means that the battery does not meet the energy recovery state, and the first flag bit is 0.

[0047] Determine whether the vehicle is in a wheel locked state as:

[0048] Compare the vehicle speed with the left front wheel speed, the right front wheel speed, the left rear wheel speed, and the right rear wheel speed, and compare the difference between the vehicle speed and the vehicle speed converted from the left front wheel speed, the right front wheel speed, the left rear wheel speed, and the right rear wheel speed. If it is greater than the specified value within n consecutive cycles, it is determined that a certain wheel of the vehicle is in a locked state, and the second flag bit is 0; otherwise, it means that the vehicle is not in a locked state, and the second flag bit is 1, where the specified value is a calibrated value.

[0049] Determine whether the vehicle is in an emergency braking working mode as: if the change rate of the brake pedal stroke is within the range of the change rate of the brake pedal stroke required for judging emergency braking, it is determined that the vehicle is in an emergency braking state, and the third flag bit is 0; otherwise, it means that the vehicle is in an emergency braking state, and the third flag bit is 1.

[0050] Determine whether the vehicle is in a turning state as: if the steering angle of the vehicle's steering wheel is within the angle threshold range for judging turning, it means that the vehicle is in a turning state, and the fourth flag bit is 0; otherwise, it means that the vehicle is not in a turning state, and the fourth flag bit is 1.

[0051] It also includes judging the working gear of energy recovery by comparing the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor, and the chassis controller sends an energy recovery working gear signal to the motor controller MCU;

[0052] The method for judging the working gear of energy recovery is as follows:

[0053] Compare the vehicle speed converted from the wheel speed with the vehicle speed collected by the vehicle speed sensor. The larger the difference V is, the lower the energy recovery gear. The steering threshold is calibrated according to the tire radius parameter;

[0054] The steering threshold includes a first threshold Φ1, a second threshold Φ2 and a third threshold Φ3, and Φ3>Φ2>Φ1;

[0055] If the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor is within the range of the first threshold Φ1, the motor energy recovery is in the maximum gear; if the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor is within the range of the second threshold Φ2, the motor energy recovery is in the intermediate gear; if the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor is within the range of the third threshold Φ3, the motor energy recovery is in the lowest gear; if the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor is greater than the third threshold Φ3, the motor energy recovery is actively turned off.

[0056] A vehicle braking smoothness control device is used to implement the vehicle braking smoothness control method described above. It includes a chassis controller, and the chassis controller is integrated with:

[0057] An acquisition module is used to acquire the wheel speed collected by the wheel speed sensor; used to acquire the vehicle speed signal collected by the vehicle speed sensor; used to acquire the angle signal collected by the steering angle sensor of the vehicle steering wheel; used to acquire the brake pedal stroke change rate signal collected by the brake pedal sensor; used to acquire the SOC information collected by the battery management system BMS;

[0058] A judgment module is used to judge whether the vehicle is in a state that meets the energy recovery working condition and the working gear of energy recovery;

[0059] A control module is used to obtain the judgment result of the judgment module, perform logical operations, and control whether to send an energy recovery enable signal and a working gear signal to the motor controller MCU according to the logical operation result, so as to perform energy recovery and power adjustment;

[0060] The wheel speed sensor, vehicle speed sensor, steering angle sensor and brake pedal sensor are all connected to the chassis controller; the chassis controller, the motor controller MCU and the battery management system BMS are all connected to the vehicle CAN network.

[0061] The wheel speed sensors include a left front wheel speed sensor, a right front wheel speed sensor, a left rear wheel speed sensor and a right rear wheel speed sensor.

Claims

1. A vehicle braking smoothness control method, characterized in that: include: By collecting the SOC information of the battery management system BMS, it is determined whether the battery allows energy recovery, and the first flag is obtained; By collecting the vehicle speed and wheel speed, it is determined whether the vehicle is in a wheel locking state, and a second flag position is obtained; By collecting the brake pedal travel change rate, it is determined whether the vehicle is in an emergency braking working mode, and a third flag position is obtained; Obtain the steering angle of the vehicle steering wheel through the angle signal collected by the vehicle steering angle sensor, determine whether the vehicle is in a right turn state, and obtain a fourth flag position; The first flag bit, the second flag bit, the third flag bit and the fourth flag bit are subjected to a logical operation to obtain an operation result. According to the value of the operation result, the chassis controller determines whether to send an energy recovery enable signal to the motor controller MCU to enable it.

2. The vehicle braking smoothness control method according to claim 1, characterized in that: The wheel speeds include a left front wheel speed, a right front wheel speed, a left rear wheel speed, and a right rear wheel speed.

3. The vehicle braking smoothness control method according to claim 2, characterized in that: The determination of whether to send an energy recovery enable signal to the motor controller MCU is based on the enabling strategy as follows: if the value of the calculation result is equal to 1, the chassis controller sends an energy recovery enable signal to the motor controller MCU; if the value of the calculation result is equal to 0, the chassis controller sends a prohibition energy recovery enable signal to the motor controller MCU.

4. The vehicle braking smoothness control method according to claim 3, characterized in that: The determination of whether the battery allows energy recovery is as follows: If the SOC information of the battery management system BMS is within the SOC threshold range required for judging energy recovery, the battery is judged to meet the energy recovery state, and the first flag bit is 1; otherwise, it means that the battery does not meet the energy recovery state, and the first flag bit is 0.

5. The vehicle braking smoothness control method according to claim 2, characterized in that: To determine whether the vehicle is in a wheel locking state: The vehicle speed is compared with the left front wheel speed, the right front wheel speed, the left rear wheel speed and the right rear wheel speed, and the difference between the vehicle speed and the vehicle speed converted from the left front wheel speed, the right front wheel speed, the left rear wheel speed and the right rear wheel speed is compared. If it is greater than the specified value within n consecutive cycles, it is determined that a wheel of the vehicle is in a locked state, and the second flag is 0; otherwise, it means that the vehicle is not in a locked state, and the second flag is 1, where the specified value is the calibration value.

6. The vehicle braking smoothness control method according to claim 1, characterized in that: The method for determining whether the vehicle is in the emergency braking mode is as follows: if the brake pedal travel change rate is within the range of the dynamic pedal travel change rate required for determining emergency braking, the vehicle is determined to be in an emergency braking state, and the third flag bit is 0; otherwise, the vehicle is in an emergency braking state, and the third flag bit is 1.

7. The vehicle braking smoothness control method according to claim 1, characterized in that: The determination of whether the vehicle is in a turning state is as follows: if the steering angle of the vehicle's steering wheel is within the angle threshold range for determining the turning state, it indicates that the vehicle is in a turning state, and the fourth flag is 0; otherwise, it indicates that the vehicle is not in a turning state, and the fourth flag is 1.

8. The vehicle braking smoothness control method according to claim 1, characterized in that: It also includes judging the working gear of energy recovery by comparing the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the vehicle speed sensor, and the chassis controller sends an energy recovery working gear signal to the motor controller MCU; The method for determining the working gear of energy recovery is: The vehicle speed converted from the wheel speed is compared with the vehicle speed collected by the vehicle speed sensor. If the difference V is larger, the gear of energy recovery is lower. The turning threshold is calibrated according to the tire radius parameter. The turning threshold includes a first threshold Φ1, a second threshold Φ2 and a third threshold Φ3, and Φ3>Φ2>Φ1; If the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the speed sensor is within the range of the first threshold value Φ1, the motor energy recovery is in the maximum gear; if the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the speed sensor is within the range of the second threshold value Φ2, the motor energy recovery is in the middle gear; if the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the speed sensor is within the range of the third threshold value Φ3, the motor energy recovery is in the lowest gear; if the difference V between the vehicle speed converted from the wheel speed and the vehicle speed collected by the speed sensor is greater than the third threshold value Φ3, the motor energy recovery is actively turned off.

9. A vehicle braking smoothness control device, used to implement the vehicle braking smoothness control method according to any one of claims 1 to 8, characterized in that: The chassis controller includes: An acquisition module is used to acquire the wheel speed collected by the wheel speed sensor; to acquire the vehicle speed signal collected by the vehicle speed sensor; to acquire the angle signal collected by the steering angle sensor of the vehicle steering wheel; and to acquire the brake pedal travel change rate signal collected by the brake pedal sensor; Used to obtain SOC information collected by the battery management system BMS; A judgment module, used to judge whether the vehicle is in a state that satisfies the energy recovery working state and the working gear of the energy recovery; The control module is used to obtain the judgment result of the judgment module and perform logic operations, and control whether to send an energy recovery enable signal and a working gear signal to the motor controller MCU according to the logic operation result to perform energy recovery and power regulation; The wheel speed sensor, vehicle speed sensor, steering angle sensor and brake pedal sensor are all connected to the chassis controller; the chassis controller, motor controller MCU and battery management system BMS are all connected to the vehicle CAN network.

10. The vehicle braking smoothness control device according to claim 9, characterized in that: The wheel speed sensors include a left front wheel speed sensor, a right front wheel speed sensor, a left rear wheel speed sensor and a right rear wheel speed sensor.

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