CN112550430B - Vehicle stability control method and system - Google Patents

Abstract

The invention provides a vehicle stability control method and a system, wherein the method comprises the steps of obtaining a first vehicle parameter; judging the current abnormal state type of the vehicle according to the first vehicle parameter; determining an output steering superposition instruction according to the first vehicle parameter and the current abnormal state type of the vehicle; and generating a torque request of the steering motor according to the output steering superposition command. The invention provides a technical scheme for realizing vehicle stability control based on an electric power steering technology, which can obtain more accurate dynamic response, bring better driving experience and improve the vehicle stability before vehicle braking intervention by combining the electric power steering technology and the vehicle dynamic control technology.

Description

Vehicle stability control method and system

technical field

The present invention relates to the technical field of vehicles, in particular to a vehicle stability control method and system.

Background technique

Traditional vehicle stability control systems such as ABS (anti-lock braking system), ESC (body stability control system), etc., are relatively mature in development. Most of them are controlled separately according to the difference between the driver's expected dynamic response and the actual vehicle dynamic response. The braking force of different wheels, thereby changing the lateral and longitudinal trajectory of the vehicle, in order to achieve the purpose of vehicle steady-state control.

The existing vehicle stability system controls the lateral trajectory of the vehicle by applying braking force. Since the lateral dynamic control of the vehicle is more sensitive than the longitudinal direction, it is difficult to control the difference in the braking force between different wheels, resulting in a sudden change in the yaw angular velocity, often with It will give the driver a bad driving experience. If the gradient of the braking pressure is too large or too slow, it will cause the system hysteresis or overshoot. Therefore, the use of the difference in the braking force between different wheels to realize the lateral control of the vehicle is effective but not perfect. The way.

SUMMARY OF THE INVENTION

In view of the problems in the prior art, the purpose of the present invention is to provide a vehicle stability control method and system, which optimizes the lateral control of the vehicle and realizes the vehicle stability control based on the electric power steering technology.

An embodiment of the present invention provides a vehicle stability control method, comprising the following steps:

Get the first vehicle parameter;

Determine the abnormal state type to which the vehicle currently belongs according to the first vehicle parameter;

Determine the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle;

A steering motor torque request for driving the electric power steering motor is generated according to the output steering superposition command.

Optionally, judging the current abnormal state type of the vehicle according to the first vehicle parameter includes the following steps:

Calculate and obtain second vehicle parameters according to the first vehicle parameters;

Obtain the determination conditions of each abnormal state type, determine the determination conditions that the first vehicle parameter and the second vehicle parameter meet, and determine the abnormal state type corresponding to the satisfied determination conditions as the current abnormal state type of the vehicle.

Optionally, the first vehicle parameter includes wheel speed, yaw rate, vehicle speed, lateral acceleration, vehicle deceleration, steering wheel angle and steering wheel torque of each wheel.

Optionally, the second vehicle parameter includes the yaw rate parameter Yaw Rate _FA of the front axle, the yaw rate parameter Yaw Rate _RA of the rear axle, the yaw rate parameter Yaw Rate _SA of the steering wheel angle, and the yaw rate of the lateral acceleration. Angular velocity parameter Yaw Rate_Ay;

Using the following formula, the second vehicle parameter is calculated according to the first vehicle parameter:

Yaw Rate _SA = SA×VS×K ₁

Among them, Wheel Speed _FL represents the wheel speed of the left front wheel, Wheel Speed _FR represents the wheel speed of the right front wheel, Track _FA represents the track of the front axle, Wheel Speed _RL represents the wheel speed of the left rear wheel, and Wheel Speed _RR represents the wheel speed of the right rear wheel. , Track _RA represents the wheel track of the rear axle, SA represents the steering wheel angle, VS represents the vehicle speed, K ₁ represents the preset first compensation coefficient, LA represents the lateral acceleration, and K ₂ represents the preset second compensation coefficient.

Optionally, the second vehicle parameter further includes the corrected wheel speed of each wheel;

The calculating and obtaining the second vehicle parameter according to the first vehicle parameter further includes the following steps:

Determine whether the vehicle is driving in a straight line according to the steering wheel angle and steering wheel torque, and obtain the wheel speeds of each wheel when the vehicle is driving in a straight line;

The corrected wheel speed of each wheel is determined according to the wheel speed of each wheel when driving in a straight line, so that the corrected wheel speed of each wheel is the same.

Optionally, the abnormal state type includes wheel state abnormality;

The determining of the determination conditions that the first vehicle parameter and the second vehicle parameter meet includes using the following steps to determine whether the first vehicle parameter and the second vehicle parameter meet the determination conditions for abnormal wheel status:

According to the yaw angular velocity parameter of the front axle, the yaw angular velocity parameter of the rear axle and the yaw angular velocity, determine whether the front axle and the rear axle are abnormal;

If the front axle and/or rear axle is abnormal, compare the corrected wheel speed of each wheel, and locate the wheel with abnormal wheel speed;

If an abnormality occurs in the front axle and/or the rear axle, it is determined that the first vehicle parameter and the second vehicle parameter meet the determination condition of the abnormal wheel state.

Optionally, the steering superposition command includes a steering torque superposition command and/or a steering angle superposition command;

The determining of the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle includes the following steps:

If the current abnormal state type of the vehicle is abnormal wheel state, determine the wheel with abnormal wheel speed, and judge the tire pressure state of the wheel with abnormal wheel speed according to the comparison of the wheel speed of the wheel with abnormal wheel speed and the wheel speed of other wheels;

Judging the running state of the vehicle according to the value of the vehicle deceleration;

When the vehicle speed is less than the preset vehicle speed threshold and the steering wheel angle is less than the preset steering angle threshold, determine the output steering torque superposition command;

When the vehicle speed is greater than or equal to the preset vehicle speed threshold and the steering wheel angle is greater than or equal to the preset steering angle threshold, the output steering angle superposition command is determined.

Optionally, the abnormal state type includes abnormal operation state;

The determining of the determination conditions that the first vehicle parameter and the second vehicle parameter meet includes adopting the following steps to determine whether the first vehicle parameter and the second vehicle parameter meet the determination conditions for abnormal operating states:

Determine whether the steering wheel angle is greater than the steering wheel angle threshold, and the steering wheel torque is greater than the steering wheel torque threshold, and if so, determine that the driver is in a steering operation;

When the driver is in the steering operation, the difference between the yaw rate parameter of the steering wheel angle and the yaw rate is calculated, and if the absolute value of the difference is greater than the first threshold, it is determined that the vehicle meets the judgment condition for abnormal operation state;

When the driver is in a steering operation, the difference between the yaw rate parameter of the lateral acceleration and the yaw rate is calculated. If the absolute value of the difference is greater than the second threshold, it is determined that the vehicle complies with the condition for determining that the operating state is abnormal.

Optionally, the steering superposition command includes a steering torque superposition command and/or a steering angle superposition command;

The determining of the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle includes the following steps:

If the current abnormal state type of the vehicle is abnormal operation state, the output steering torque superposition command is determined according to the steering wheel angle, the steering wheel torque and the yaw rate.

Optionally, the abnormal state type includes abnormal road conditions;

The determining of the determination conditions that the first vehicle parameter and the second vehicle parameter meet includes adopting the following steps to determine whether the first vehicle parameter and the second vehicle parameter meet the determination conditions for abnormal road conditions:

Determine whether the steering wheel angle and the steering wheel torque have not changed within a preset time range, and if so, determine that the driver is in a steering hold operation;

When the driver is in the steering hold operation, the change value of the yaw rate-related parameter within a preset time period is monitored, and if the change value exceeds the third threshold, it is determined that the vehicle meets the judgment condition for abnormal road conditions. The parameters include one or more of the yaw angular velocity detected by the yaw angle sensor, the calculated yaw angular velocity parameter of the front axle, and the calculated yaw angular velocity parameter of the rear axle.

Optionally, the steering superposition command includes a steering torque superposition command and/or a steering angle superposition command;

The determining of the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle includes the following steps:

If the current abnormal state type of the vehicle is abnormal road state, determine whether the vehicle speed is greater than the vehicle speed threshold, and if the vehicle speed is greater than the vehicle speed threshold, determine the output steering torque superposition command according to the yaw rate and the vehicle speed;

If the vehicle speed is less than or equal to the vehicle speed threshold, the output steering angle superposition command is determined according to the yaw rate and the vehicle speed.

Optionally, the generating the torque request for the steering motor according to the output steering superposition command includes the following steps:

Determine an operation steering command according to the steering wheel angle and steering wheel torque;

A steering motor torque request is generated according to the output steering superimposed command and the steering command superimposed by the operation steering command.

Optionally, after the output steering superposition instruction is superimposed with the operation steering instruction, the following steps are also included:

Determine whether the corresponding vehicle speed is greater than a fourth threshold after the output steering superposition command and the operation steering command are superimposed;

If the vehicle speed is greater than the fourth threshold, it is determined whether the superimposed steering torque value after the output steering superposition command and the operation steering command is superimposed is greater than a preset torque threshold, and if so, a steering motor is generated according to the preset torque threshold torque request, otherwise a steering motor torque request is generated based on the steering torque overlay value.

An embodiment of the present invention further provides a vehicle stability control system, which is applied to the vehicle stability control method, and the system includes:

a vehicle dynamic monitoring module, used to obtain the first vehicle parameter;

an abnormal state type monitoring module, configured to determine the current abnormal state type of the vehicle according to the first vehicle parameter;

a vehicle dynamic suppression module, configured to determine the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle;

The steering request generating module is configured to generate a steering motor torque request for driving the electric power steering motor according to the output steering superposition command.

Optionally, the vehicle dynamic monitoring module is further configured to calculate and obtain second vehicle parameters according to the first vehicle parameters;

The abnormal state type monitoring module is used to obtain the judgment conditions of each abnormal state type, determine the judgment conditions that the first vehicle parameter and the second vehicle parameter meet, and determine the abnormal state type corresponding to the met judgment conditions. It is the current abnormal state type of the vehicle.

Optionally, the steering request generation module is configured to determine an operation steering command according to the steering wheel angle and the steering wheel torque, and after superimposing the output steering superposition command and the operation steering command, determine whether the corresponding vehicle speed is greater than the first speed. Four thresholds;

If the vehicle speed is greater than the fourth threshold, it is determined whether the superimposed steering torque value after the output steering superposition command and the operation steering command is superimposed is greater than a preset torque threshold, and if so, a steering motor is generated according to the preset torque threshold torque request, otherwise a steering motor torque request is generated based on the steering torque overlay value.

Optionally, the system further includes a vehicle lateral control module for sending the steering motor torque request to an electric power steering motor.

The vehicle stability control method and system provided by the present invention have the following advantages:

The present invention provides a technical solution for realizing vehicle stability control based on the electric power steering technology. By combining the electric power steering technology and the vehicle dynamic control technology, a more accurate dynamic response can be obtained, a better driving experience can be brought, and the driving experience can be improved. Vehicle stability before vehicle braking intervention, suitable for a wide range of applications.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings.

FIG. 1 is a flowchart of a vehicle stability control method according to an embodiment of the present invention;

2 is a schematic structural diagram of a vehicle stability control system according to an embodiment of the present invention;

3 is a schematic diagram of input and output of a vehicle stability control system according to an embodiment of the present invention

4 is a schematic diagram of input and output of a vehicle dynamic monitoring module according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of the input and output of the abnormal collision monitoring module according to an embodiment of the present invention.

FIG. 6 is a flowchart of a wheel state abnormality determination according to an embodiment of the present invention;

FIG. 7 is a flowchart of an abnormal operation state determination according to an embodiment of the present invention;

FIG. 8 is a flowchart of road surface state abnormality determination according to an embodiment of the present invention.

Detailed ways

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments, however, can be embodied in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their repeated descriptions will be omitted.

As shown in FIG. 1, in order to solve the technical problems in the prior art, the present invention provides a vehicle stability control method, which includes the following steps:

S100: obtain the first vehicle parameter;

S200: Determine the abnormal state type to which the vehicle currently belongs according to the first vehicle parameter;

S300: Determine an output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle, where the steering superposition command includes a steering torque superposition command and/or a steering angle superposition command;

S400: Generate a steering motor torque request for driving the electric power steering motor according to the output steering superposition command.

Therefore, the vehicle stability control method of the present invention provides a technical solution for realizing vehicle stability control based on the electric power steering technology. The abnormal state and abnormal state type of the vehicle are identified through steps S100 and S200, and the abnormal state and type of the abnormal state are identified through steps S300 and S400. The steering motor torque request that can drive the electric power steering motor is generated according to the abnormal state type, so that the electric power steering technology and the vehicle dynamic control technology can be combined to obtain a more precise dynamic response, improve the vehicle stability before the vehicle braking intervention, and Bring a better driving experience.

As shown in FIG. 2, the present invention also provides a vehicle stability control system, the system includes:

The vehicle dynamic monitoring module M100 is used to obtain the first vehicle parameter, that is, the above step S100 is executed;

An abnormal state type monitoring module M200, configured to determine the current abnormal state type of the vehicle according to the first vehicle parameter, that is, to execute the above step S200;

The vehicle dynamics suppression module M300 is configured to determine the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle, where the steering superposition command includes a steering torque superposition command and/or a steering angle superposition command, that is, execute above step S300;

The steering request generating module M400 is configured to generate a steering motor torque request for driving the electric power steering motor according to the output steering superposition command, that is, the above-mentioned step S400 is executed.

Further, in this embodiment, the vehicle stability control system may further include a vehicle lateral control module M500 for sending the steering motor torque request to the electric power steering motor.

Therefore, the vehicle stability control system of this embodiment recognizes the abnormal state and the abnormal state type of the vehicle through the vehicle dynamic monitoring module M100 and the abnormal state type monitoring module M200, and uses the vehicle dynamic suppression module M300 and the steering request generation module M400 to identify the abnormal state according to the abnormal state. The type generates a steering motor torque request that can drive the electric power steering motor, and can send the steering motor torque request to the electric power steering motor through the vehicle side control module M500, so that the electric power steering technology and the vehicle dynamic control technology can be combined to obtain more Precise dynamic response for improved vehicle stability before vehicle braking intervention.

The vehicle stability control system of the present invention can be directly installed inside the electric power steering system, for example, in the electronic control unit of the electric power steering system, and the first vehicle parameter can be directly obtained from various existing sensors of the vehicle without additional Add hardware devices. However, the present invention is not limited to this. In other embodiments, the vehicle stability control system may also be set in other systems, or an electronic control unit may be set separately to perform the functions of the vehicle stability control system, etc., which belong to the present invention. within the scope of protection.

As shown in FIG. 3 , it is a schematic diagram of the input and output of the vehicle stability control system in this embodiment. Wherein, the left side of the vehicle stability control system is the first vehicle parameter. In this embodiment, the first vehicle parameter includes the wheel speed of each wheel (left front wheel speed, right front wheel speed, left rear wheel speed wheel speed and right rear wheel speed), yaw rate, vehicle speed, lateral acceleration, vehicle deceleration, steering wheel angle and steering wheel torque, on the right side of the vehicle stability control system are components that receive output commands, mainly including electric power steering A motor and vehicle human-machine interaction system configured to perform power steering actions based on steering motor torque requests. When the vehicle detects an abnormal state, a reminder information can be sent to the driver through the vehicle human-machine interaction system (HMI).

In this embodiment, in the step S200, the following steps are used to determine the current abnormal state type of the vehicle according to the first vehicle parameter:

The vehicle dynamic monitoring module M100 calculates and obtains the second vehicle parameter according to the first vehicle parameter;

The abnormal state type monitoring module M200 obtains the determination conditions of each abnormal state type, determines the determination conditions that the first vehicle parameter and the second vehicle parameter conform to, and determines the abnormal state type corresponding to the conformed determination conditions as: The current abnormal state type of the vehicle.

As shown in FIG. 4 , in this embodiment, the second vehicle parameters include the yaw rate parameter YawRate _FA of the front axle, the yaw rate parameter Yaw Rate _RA of the rear axle, and the yaw rate parameter Yaw Rate _SA of the steering wheel angle and the yaw rate parameter Yaw Rate_Ay for lateral acceleration.

Using the following formula, the second vehicle parameter is calculated according to the first vehicle parameter:

Yaw Rate _SA = SA×VS×K ₁

Among them, Wheel Speed _FL represents the wheel speed of the left front wheel, Wheel Speed _FR represents the wheel speed of the right front wheel, Track _FA represents the track of the front axle, Wheel Speed _RL represents the wheel speed of the left rear wheel, and Wheel Speed _RR represents the wheel speed of the right rear wheel. , Track _RA represents the wheel track of the rear axle, SA represents the steering wheel angle, VS represents the vehicle speed, K ₁ represents the preset first compensation coefficient, LA represents the lateral acceleration, and K ₂ represents the preset second compensation coefficient.

Further, the second vehicle parameter further includes the corrected wheel speed of each wheel: the corrected wheel speed of the left front wheel, the corrected wheel speed of the right front wheel, the corrected wheel speed of the left rear wheel and the corrected wheel speed of the right rear wheel.

The calculating and obtaining the second vehicle parameter according to the first vehicle parameter further includes the following steps:

Determine whether the vehicle is driving in a straight line according to the steering wheel angle and steering wheel torque, and obtain the wheel speeds of each wheel when the vehicle is driving in a straight line;

The corrected wheel speed of each wheel is determined according to the wheel speed of each wheel when driving in a straight line, so that the corrected wheel speed of each wheel is the same.

Among them, when the steering wheel angle is 0 degrees, which is the middle position, and the driver has no force on the steering wheel, and the steering wheel torque is less than a certain value, then the system is defined as driving in a straight line, and the rotational speed of each wheel should be the same. Therefore, it is judged whether the wheel speeds of all the wheels are consistent. If the wheel speeds of the four wheels are very similar, then the state of each wheel is normal, and the corrected wheel speed is determined as the common wheel speed of the four wheels. If the wheel speed of one wheel differs greatly from that of the other three wheels, the corrected wheel speed of the wheel with the great difference is also set according to the wheel speeds of the other three wheels.

As shown in FIG. 5 , in this embodiment, the abnormal state types include wheel state abnormality, operating state abnormality, and road surface state abnormality. However, the present invention is not limited thereto, and in other optional embodiments, the abnormal state types may also include other types of abnormal states, or only include one or both of abnormal wheel states, abnormal operating states and abnormal road conditions.

As shown in FIG. 6 , in this embodiment, the determination of the determination conditions that the first vehicle parameter and the second vehicle parameter meet includes that the abnormal state type monitoring module M200 adopts the following steps to determine the first vehicle parameter. Whether the first vehicle parameter and the second vehicle parameter meet the conditions for determining whether the wheel state is abnormal:

According to the yaw angular velocity parameter of the front axle, the yaw angular velocity parameter of the rear axle and the yaw angular velocity, determine whether the front axle and the rear axle are abnormal;

Here, according to the principle of Ackerman's angle, the yaw rate of the front and rear axles can be calculated by the left and right wheels of the front and rear axles, and the yaw rate sensor installed on the vehicle can be compared to determine which axle has a problem with the calculation. Specifically, the yaw rate parameter and the yaw rate of the front axle are compared, and if the difference is greater than the preset yaw angle difference threshold, it is determined that the front axle is abnormal, and the yaw rate parameter and the yaw rate of the rear axle are compared. If the difference is greater than the preset yaw angle difference threshold, it is judged that the rear axle is abnormal;

If the front axle and/or rear axle is abnormal, compare the corrected wheel speed of each wheel, and locate the wheel with abnormal wheel speed; When the corrected wheel speed differs greatly, it means that the wheel is abnormal. When the front axle is abnormal, the corrected wheel speed is determined by the rear wheel speed. When the rear axle is abnormal, the corrected wheel speed is determined by the front wheel speed. The corrected wheel speeds of the wheels are all the same, and the actual wheel speeds may be different. Wheels with a large difference between the actual wheel speed and the corrected wheel speed are abnormal wheels;

If an abnormality occurs in the front axle and/or the rear axle, it is determined that the first vehicle parameter and the second vehicle parameter meet the determination condition of the abnormal wheel state.

In this embodiment, the vehicle dynamics suppression module M300 adopts the following steps to determine the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle:

If the current abnormal state type of the vehicle is abnormal wheel state, determine the wheel with abnormal wheel speed, and judge the tire pressure state of the wheel with abnormal wheel speed according to the comparison of the wheel speed of the wheel with abnormal wheel speed and the wheel speed of other wheels;

Specifically, the tire pressure status of the wheel with abnormal wheel speed can be judged by comparing the speed of the wheel with abnormal speed with other wheel speeds. For the tire pressure, when the W value is within the first range, the tire has a puncture failure, and when the W value is within the second range, the tire has a flat tire failure, etc.

Judging the running state of the vehicle (acceleration, deceleration, constant speed) according to the value of the vehicle deceleration;

When the vehicle dynamic is small, determine the output steering torque superposition command, where the small vehicle dynamic means that the vehicle speed is less than a set vehicle speed threshold and the steering wheel angle is less than a set corner threshold;

When the vehicle dynamic is large, the output steering angle superposition command is determined, where the large vehicle dynamic refers to that the vehicle speed is greater than or equal to a set vehicle speed threshold or the steering wheel angle is greater than or equal to a set turning angle threshold.

Among them, when determining the output steering torque superposition command and the output steering angle superposition command, the corresponding output value can be determined according to a preset adaptive model (for example, a PID model with preset model parameters, etc.). It is possible to simply look up the table, that is, look up a mapping relationship table between at least some of the preset first vehicle parameters and the second vehicle parameters and the steering torque superposition command, or look up a preset first vehicle parameter and second vehicle parameter. A mapping relationship table between at least some of the vehicle parameters and the steering angle superposition command. Specifically, when the wheel state is abnormal, the corresponding steering torque superposition command or steering angle superposition command can be obtained by looking up a table according to the position of the abnormal wheel, the tire pressure of the abnormal wheel, and the running state of the vehicle.

As shown in FIG. 7 , in this embodiment, the determination of the determination conditions that the first vehicle parameter and the second vehicle parameter meet includes that the abnormal state type monitoring module M200 adopts the following steps to determine the first vehicle parameter. Whether the first vehicle parameter and the second vehicle parameter meet the conditions for determining whether the operating state is abnormal:

Determine whether the steering wheel angle is greater than the steering wheel angle threshold, and the steering wheel torque is greater than the steering wheel torque threshold, and if so, determine that the driver is in a steering operation;

When the driver is in the steering operation, the difference between the yaw rate parameter of the steering wheel angle and the yaw rate is calculated. If the absolute value of the difference is greater than the first threshold, it is determined that the vehicle meets the judgment condition for abnormal operation state, indicating that there is understeer. question;

When the driver is in the steering operation, the difference between the yaw angular velocity parameter of the lateral acceleration and the yaw angular velocity is calculated. If the absolute value of the difference is greater than the second threshold, it is determined that the vehicle meets the judgment condition of abnormal operation state, indicating that there is oversteering The problem.

The vehicle dynamic suppression module M300 adopts the following steps to determine the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle:

If the current abnormal state type of the vehicle is abnormal operation state, the output steering torque superposition command is determined according to the steering wheel angle, the steering wheel torque and the yaw rate.

Among them, when determining the output steering torque superposition command and the output steering angle superposition command, the corresponding output value can be determined according to a preset adaptive model (for example, a PID model with preset model parameters, etc.). It is possible to simply look up the table, that is, look up a mapping relationship table between at least some of the preset first vehicle parameters and the second vehicle parameters and the steering torque superposition command, or look up a preset first vehicle parameter and second vehicle parameter. A mapping relationship table between at least some of the vehicle parameters and the steering angle superposition command. Specifically, when the operating state is abnormal, it can be determined according to whether the abnormal operating state is understeer or oversteer, the difference between the yaw angular velocity parameter of the steering wheel angle and the yaw angular velocity, and the yaw angular velocity parameter and yaw angular velocity of the lateral acceleration. The difference value and other parameters are used to look up the table to determine the output steering torque superposition command or steering angle superposition command.

As shown in FIG. 8 , the determining conditions that the first vehicle parameter and the second vehicle parameter meet include that the abnormal state type monitoring module M200 adopts the following steps to determine the first vehicle parameter and the second vehicle parameter. Whether the vehicle parameters meet the judgment conditions for abnormal road conditions:

Determine whether the steering wheel angle and the steering wheel torque have not changed within a preset time range, and if so, determine that the driver is in a steering hold operation;

When the driver is in the steering hold operation, the change value of the yaw rate-related parameter within a preset time period is monitored, and if the change value exceeds the third threshold, it is determined that the vehicle meets the judgment condition for abnormal road conditions. The parameters include one or more of the yaw angular velocity detected by the yaw angle sensor, the calculated yaw angular velocity parameter of the front axle, and the calculated yaw angular velocity parameter of the rear axle.

In this embodiment, the vehicle dynamics suppression module M300 adopts the following steps to determine the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle:

If the current abnormal state type of the vehicle is abnormal road state, determine whether the vehicle speed is greater than the vehicle speed threshold, and if the vehicle speed is greater than the vehicle speed threshold, determine the output steering torque superposition command according to the yaw rate and the vehicle speed;

If the vehicle speed is less than or equal to the vehicle speed threshold, the output steering angle superposition command is determined according to the yaw rate and the vehicle speed. The vehicle speed threshold can be set in advance according to the chassis structure and characteristics of different vehicles.

Among them, when determining the output steering torque superposition command and the output steering angle superposition command, the corresponding output value can be determined according to a preset adaptive model (for example, a PID model with preset model parameters, etc.). It is possible to simply look up the table, that is, look up a mapping relationship table between at least some of the preset first vehicle parameters and the second vehicle parameters and the steering torque superposition command, or look up a preset first vehicle parameter and second vehicle parameter. A mapping relationship table between at least some of the vehicle parameters and the steering angle superposition command. Specifically, when there is an abnormal road condition, a table can be looked up according to the change value of the yaw rate related parameter to determine the corresponding steering torque superposition command and steering angle superposition command.

In this embodiment, the generating a steering motor torque request according to the output steering superposition command includes the following steps:

Determine the operation steering command according to the steering wheel angle and the steering wheel torque, wherein the operation steering command can be determined by the electric power steering system according to the input of the steering wheel;

A steering motor torque request is generated according to the output steering superimposed command and the steering command superimposed by the operation steering command.

In this embodiment, after the output steering superposition command and the operation steering command are superimposed, the step of limiting the maximum torque of the steering motor according to the vehicle speed is also included, so as to avoid applying excessively large torque when the vehicle speed is high. Steering motor torque, specifically, includes the following steps:

After the output steering superposition command is superimposed with the operation steering command, determine whether the corresponding vehicle speed is greater than a fourth threshold;

If yes, the maximum value of the superimposed steering motor torque is set as a preset steering torque threshold to limit the steering motor torque.

Specifically, when the vehicle speed is greater than the fourth threshold, it is determined whether the superimposed steering torque value after the output steering superposition command and the operation steering command is superimposed is greater than a preset torque threshold, and if so, according to the preset A torque threshold generates a steering motor torque request, otherwise a steering motor torque request is generated based on the steering torque stack value.

Wherein, generating the steering motor torque request according to the preset torque threshold may be to multiply the steering torque superimposed value by a corresponding coefficient according to the limit of the preset torque threshold to reduce the steering torque superimposed value, and the coefficient can be obtained by looking up a table, or Directly sets the steering torque value in the steering motor torque request to the preset torque threshold.

To sum up, compared with the prior art, the present invention provides a technical solution for realizing vehicle stability control based on the electric power steering technology. By combining the electric power steering technology and the vehicle dynamic control technology, a more precise dynamic response can be obtained. , and bring a better driving experience, improve vehicle stability before vehicle braking intervention, suitable for large-scale promotion and application.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (14)

1. A vehicle stability control method characterized by comprising the steps of:

acquiring a first vehicle parameter;

judging the current abnormal state type of the vehicle according to the first vehicle parameter;

determining an output steering superposition instruction according to the first vehicle parameter and the current abnormal state type of the vehicle;

generating a steering motor torque request for driving an electric power steering motor according to the output steering superposition command;

the method for generating the torque request of the steering motor according to the output steering superposition command comprises the following steps:

determining an operation steering command according to the steering wheel angle and the steering wheel torque;

generating a steering motor torque request according to the steering instruction after the output steering superposition instruction and the operation steering instruction are superposed;

after the output steering superposition command and the operation steering command are superposed, the method further comprises the following steps:

judging whether the corresponding vehicle speed is greater than a fourth threshold value or not after the output steering superposition instruction is superposed with the operation steering instruction;

and if the vehicle speed is greater than a fourth threshold value, judging whether a steering torque superposition value obtained after the output steering superposition instruction and the operation steering instruction are superposed is greater than a preset torque threshold value, if so, generating a steering motor torque request according to the preset torque threshold value, otherwise, generating the steering motor torque request according to the steering torque superposition value.

2. The vehicle stability control method according to claim 1, wherein the determining a current abnormal state type of the vehicle according to the first vehicle parameter includes the steps of:

calculating to obtain a second vehicle parameter according to the first vehicle parameter;

and acquiring the judging conditions of the abnormal state types, judging the judging conditions met by the first vehicle parameters and the second vehicle parameters, and determining the abnormal state type corresponding to the meeting judging conditions as the current abnormal state type of the vehicle.

3. The vehicle stability control method according to claim 2, characterized in that the first vehicle parameters include wheel speeds of the respective wheels, yaw rate, vehicle speed, lateral acceleration, vehicle deceleration, steering wheel angle, and steering wheel torque.

4. The vehicle stability control method according to claim 3, wherein the second vehicle parameter includes a Yaw-Rate parameter Yaw Rate of a front axle _FA And a Yaw Rate parameter Yaw Rate of the rear axle _RA Yaw Rate parameter Yaw Rate of steering wheel angle _SA And Yaw Rate parameter Yaw Rate _ Ay of lateral acceleration;

calculating the second vehicle parameter according to the first vehicle parameter by adopting the following formula:

Yaw Rate _SA ＝SA×VS×K ₁

wherein, the Wheel Speed _FL Indicating the left front Wheel Speed, Wheel Speed _FR Indicating the wheel speed, Track, of the right front wheel _FA Wheel track of front axle, Wheel Speed _RL Indicating the left rear Wheel Speed, Wheel Speed _RR Indicating the speed of the right rear wheel, Track _RA Representing the track of the rear axle, SA the steering wheel angle, VS the vehicle speed, K ₁ Representing a preset first compensation factor, LA representing lateral acceleration, K ₂ Representing a preset second compensation factor.

5. The vehicle stability control method according to claim 4, wherein the second vehicle parameter further includes corrected wheel speeds of the respective wheels;

the second vehicle parameter is calculated according to the first vehicle parameter, and the method further comprises the following steps:

judging whether the vehicle is in straight line running or not according to the steering wheel rotation angle and the steering wheel torque, and acquiring the wheel speed of each wheel when the vehicle is in straight line running;

the corrected wheel speeds of the respective wheels are determined based on the wheel speeds of the respective wheels at the time of straight running so that the corrected wheel speeds of the respective wheels are the same.

6. The vehicle stability control method according to claim 5, characterized in that the abnormal state type includes a wheel state abnormality;

the determining the determination conditions that the first vehicle parameter and the second vehicle parameter meet includes determining whether the first vehicle parameter and the second vehicle parameter meet the determination conditions that the wheel state is abnormal, using:

judging whether the front axle and the rear axle are abnormal or not according to the yaw velocity parameter of the front axle, the yaw velocity parameter of the rear axle and the yaw velocity;

if the front axle and/or the rear axle is abnormal, comparing the corrected wheel speeds of all the wheels, and positioning the wheels with abnormal wheel speeds;

and if the front axle and/or the rear axle are abnormal, determining that the first vehicle parameter and the second vehicle parameter accord with the determination condition of the abnormal wheel state.

7. The vehicle stability control method according to claim 6, characterized in that the steering superimposition command includes a steering torque superimposition command and/or a steering angle superimposition command;

the step of determining the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle comprises the following steps:

if the current abnormal state type of the vehicle is abnormal wheel state, determining the wheel with abnormal wheel speed, and judging the tire pressure state of the wheel with abnormal wheel speed according to the comparison between the wheel speed of the wheel with abnormal wheel speed and the wheel speeds of other wheels;

judging the vehicle running state according to the value of the vehicle deceleration;

when the vehicle speed is less than a preset vehicle speed threshold and the steering wheel angle is less than a preset steering angle threshold, determining an output steering torque superposition instruction;

and when the vehicle speed is greater than or equal to a preset vehicle speed threshold value and the steering wheel angle is greater than or equal to a preset steering angle threshold value, determining an output steering angle superposition instruction.

8. The vehicle stability control method according to claim 5, characterized in that the abnormal state type includes an operation state abnormality;

the determining the determination conditions that the first vehicle parameter and the second vehicle parameter meet comprises determining whether the first vehicle parameter and the second vehicle parameter meet the determination conditions that the operating state is abnormal by adopting the following steps:

judging whether the steering wheel angle is larger than a steering wheel angle threshold value or not, and determining that the driver is in steering operation if the steering wheel torque is larger than a steering wheel torque threshold value;

when a driver is in steering operation, calculating a difference value between a yaw rate parameter of a steering wheel angle and a yaw rate, and if the absolute value of the difference value is greater than a first threshold value, determining that the vehicle meets the judgment condition of abnormal operation state;

and when the driver is in steering operation, calculating the difference value between the yaw rate parameter of the lateral acceleration and the yaw rate, and if the absolute value of the difference value is greater than a second threshold value, determining that the vehicle meets the judgment condition of the abnormal operation state.

9. The vehicle stability control method according to claim 8, characterized in that the steering superimposition command includes a steering torque superimposition command and/or a steering angle superimposition command;

the step of determining the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle comprises the following steps:

and if the current abnormal state type of the vehicle is abnormal in the operation state, determining an output steering torque superposition command according to the steering wheel angle, the steering wheel torque and the yaw angular velocity.

10. The vehicle stability control method according to claim 5, characterized in that the abnormal state type includes a road surface state abnormality;

the determination condition that the first vehicle parameter and the second vehicle parameter meet comprises the following steps:

judging whether the steering wheel angle and the steering wheel torque are not changed within a preset time range, and if so, determining that a driver is in steering holding operation;

monitoring a change value of a yaw-rate-related parameter, which includes one or more of a yaw rate detected by a yaw-rate sensor, a calculated yaw-rate parameter of a front axle, and a calculated yaw-rate parameter of a rear axle, over a preset period of time while the driver is in the steering-hold operation, and determining that the vehicle meets a determination condition for a road surface state abnormality if the change value exceeds a third threshold value.

11. The vehicle stability control method according to claim 10, characterized in that the steering superimposition command includes a steering torque superimposition command and/or a steering angle superimposition command;

the step of determining the output steering superposition command according to the first vehicle parameter and the current abnormal state type of the vehicle comprises the following steps:

if the current abnormal state type of the vehicle is abnormal road surface state, judging whether the vehicle speed is greater than a vehicle speed threshold value, and if the vehicle speed is greater than the vehicle speed threshold value, determining an output steering torque superposition command according to the yaw angular speed and the vehicle speed;

and if the vehicle speed is less than or equal to the vehicle speed threshold value, determining the output steering angle superposition instruction according to the yaw angular speed and the vehicle speed.

12. A vehicle stability control system characterized by being applied to the vehicle stability control method according to any one of claims 1 to 11, the system comprising:

the vehicle dynamic monitoring module is used for acquiring a first vehicle parameter;

the abnormal state type monitoring module is used for judging the current abnormal state type of the vehicle according to the first vehicle parameter;

the vehicle dynamic suppression module is used for determining an output steering superposition instruction according to the first vehicle parameter and the current abnormal state type of the vehicle;

the steering request generating module is used for generating a steering motor torque request for driving an electric power-assisted steering motor according to the output steering superposition command;

the steering request generating module is further used for determining an operation steering instruction according to the steering wheel angle and the steering wheel torque, and judging whether the corresponding vehicle speed is greater than a fourth threshold value or not after the output steering superposition instruction and the operation steering instruction are superposed;

and if the vehicle speed is greater than a fourth threshold value, judging whether a steering torque superposition value obtained after the output steering superposition instruction and the operation steering instruction are superposed is greater than a preset torque threshold value, if so, generating a steering motor torque request according to the preset torque threshold value, otherwise, generating the steering motor torque request according to the steering torque superposition value.

13. The vehicle stability control system of claim 12, wherein the vehicle dynamics monitoring module is further configured to calculate a second vehicle parameter from the first vehicle parameter;

the abnormal state type monitoring module is used for acquiring the judgment conditions of each abnormal state type, judging the judgment conditions met by the first vehicle parameter and the second vehicle parameter, and determining the abnormal state type corresponding to the met judgment conditions as the current abnormal state type of the vehicle.

14. The vehicle stability control system of claim 12, further comprising a vehicle lateral control module to send the steering motor torque request to an electric power steering motor.

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