Steering control method for assisting stability of automobile and automobile

Abstract

The invention discloses a steering control method for assisting vehicle stability and an automobile. The method comprises the steps that after triggering conditions and activation conditions are met, steering wheel force needing to be corrected is calculated according to the current vehicle state, and the corrected steering wheel force obtained through calculation is superposed to a steering system to conduct correction control on the direction of the steering system. The power-assisted steering system has the advantages that steering control is added on the basis of power-assisted steering, obvious mechanical vibration and noise cannot be generated, the dynamic stability of a vehicle can be effectively kept, and the riding experience and the driving safety are improved. When the road surface between the left side and the right side of the vehicle is unbalanced, the stability of the vehicle can be ensured by automatically applying the correction force, so that the vehicle can stably and reliably run.

Description

Technical Field

[0001] The invention relates to the field of automobile stability control, and in particular to a steering control method and an automobile for assisting vehicle stability. Background Art

[0002] At present, when a car accelerates or decelerates on a road with inconsistent adhesion coefficients on the left and right sides, the vehicle will deflect to one side, making it unstable, due to the uneven force on the left and right sides of the vehicle body. This is very unfriendly to drivers with little driving experience and may even cause unnecessary traffic accidents. The steering control of traditional cars only considers steering assistance, reducing the steering force required for users to turn and improving the user's steering experience.

[0003] For example, the patent application No. 200810196187.1 is an automotive electric power steering system and its motor control method, the disclosed contents of which include: an electronic control unit, and a steering wheel torque sensing module, a vehicle speed sensing module, a motor drive module and a power motor absorption current detection module connected thereto, and the electronic control unit also includes a PID controller. In the electric power steering system, the control process of the power motor adopts a self-selected PID control method. Since the external load of the motor is different in the two working processes of assisting and returning, the characteristics of the motor are also different, so different control methods can be used in different working states to achieve a good control effect. The stability of the system operation is greatly improved, so that the power motor can output the set torque in a timely and accurate manner, and the steering wheel rotates smoothly, continuously and without vibration within the full range of travel.

[0004] It can be seen that the main consideration in traditional automobile steering control is steering assistance, which provides users with steering assistance and facilitates the user to turn the steering wheel. However, when the car accelerates or decelerates on a road with inconsistent adhesion coefficients on the left and right sides of the road, due to uneven force on the left and right sides of the car body, the vehicle will deflect to one side, making the vehicle unstable, causing driving safety risks. Therefore, how to avoid this situation through steering control is a technical problem that needs to be solved. No relevant technology is disclosed in the prior art. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a steering control method and a vehicle for assisting vehicle stability, so that the vehicle can continue to maintain vehicle driving stability through steering control, avoiding safety risks caused by steering deviation due to instability on the left and right sides.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a steering control method for assisting vehicle stability, which calculates the required corrected steering wheel force through the current vehicle state after the trigger conditions and activation conditions are met, and superimposes the calculated corrected steering wheel force on the steering system to perform correction control on the direction of the steering system.

[0007] The trigger condition is that the vehicle is traveling in the forward direction.

[0008] Based on the vehicle's wheel speed, vehicle speed, yaw rate, lateral acceleration, longitudinal acceleration, road slope, driver-requested braking force, wheel-end torque and other monitoring parameters, it is determined whether the activation conditions are met.

[0009] Calculating the steering wheel force required for correction includes: calculating the unbalanced steering torque of the whole vehicle through the wheel end torque, calculating the steering wheel target angle required to offset the unbalanced steering torque currently applied to the whole vehicle through the whole vehicle model, and converting it into steering wheel torque.

[0010] The force acting on the steering wheel is the additional auxiliary force required to ensure that the vehicle's current operating condition follows the driving trajectory intended by the driver, calculated based on parameters such as vehicle speed, deceleration, wheel-end torque, and steering wheel angle.

[0011] After the trigger conditions and activation conditions are met, if it is detected that the driver's hand force is greater than the set threshold and lasts for the set time, the steering control corresponding to the driver's hand force will be responded to first.

[0012] The vehicle's driving direction is determined by the gear position signal detected by the gear position sensor or the wheel speed signal detected by the wheel speed sensor.

[0013] Calculating the steering wheel force that needs to be corrected includes: recognizing road information through a camera, calculating the unbalanced torque received by the entire vehicle in combination with the driver's steering intention, calculating the target steering wheel angle required to offset the unbalanced steering torque currently received by the entire vehicle through a vehicle model, and converting it into a steering wheel torque.

[0014] A car is integrated with the steering control method for assisting vehicle stability.

[0015] The advantages of the present invention are: adding steering control on the basis of steering assistance, without generating obvious mechanical vibration and noise, effectively maintaining the dynamic stability of the vehicle, improving the riding experience and driving safety. When the vehicle is unbalanced due to the road surface between the left and right sides of the vehicle, the stability of the vehicle can be ensured by automatically applying a correction force, so that the vehicle can drive stably and reliably. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following is a brief description of the contents expressed in the drawings of the present invention and the symbols in the drawings:

[0017] Figure 1 Flow chart of the control method of the present invention. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention will be further explained in detail below by describing the optimal embodiment with reference to the accompanying drawings.

[0019] The present invention provides a steering control method for assisting vehicle stability. The method enters a start function after a trigger condition and an activation condition are met. After the function is started, the steering wheel force required for correction is calculated according to the current vehicle state, and the calculated corrected steering wheel force is superimposed on the steering system to perform correction control on the direction of the steering system.

[0020] Among them: the trigger condition is that the vehicle is traveling in the forward direction, which can be judged by the gear position signal detected by the gear position sensor and the wheel speed signal detected by the wheel speed sensor. When the gear is D gear and the vehicle speed is not 0, the driving direction is in the forward direction.

[0021] Based on the vehicle's wheel speed, vehicle speed, yaw rate, lateral acceleration, longitudinal acceleration, road slope, driver-requested braking force, wheel-end torque and other monitoring parameters, it is determined whether the activation conditions are met. The activation conditions can be reasonably set according to the actual situation, such as the vehicle speed is greater than the minimum vehicle speed trigger threshold, and the driver's request pressure is greater than the minimum trigger threshold.

[0022] Calculating the steering wheel force required for correction includes: calculating the unbalanced steering torque of the whole vehicle through the wheel-end torque, calculating the target steering wheel angle required to offset the unbalanced steering torque currently applied to the whole vehicle through the whole vehicle model, and converting it into the steering wheel torque. Calculating the unbalanced steering torque based on the wheel-end torque and converting it into the steering wheel torque includes: calculating the forces of the four wheels in the X and Y directions of the whole vehicle through the wheel-end torque, synthesizing the yaw torque to the center of mass through the relative positions of the four wheels to the center of mass of the vehicle. The X and Y directions are respectively: longitudinal is X and lateral is Y.

[0023] The force acting on the steering wheel is the additional auxiliary force required to ensure that the vehicle's current working condition follows the driving trajectory intended by the driver, calculated based on parameters such as vehicle speed, deceleration, wheel-end torque, and steering wheel angle. The calculation of the force acting on the steering wheel includes: calculating the lateral force to be compensated through the yaw moment, and calculating the tire slip angle required for the lateral force based on the tire model. The required steering angle is calculated using the steady-state steering equation and Newton's second law.

[0024] After the trigger conditions and activation conditions are met, if it is detected that the driver's hand force is greater than the set threshold and lasts for the set time, the steering control corresponding to the driver's hand force will be responded to first.

[0025] Calculating the steering wheel force required for correction includes: using the camera to identify road information, combining the driver's steering intention to calculate the unbalanced torque received by the vehicle, and using the vehicle model to calculate the target steering wheel angle required to offset the unbalanced steering torque currently received by the vehicle, and converting it into steering wheel torque. The camera can plan the vehicle's driving trajectory, and use the offset of the driving trajectory as the input for correction compensation, that is, the greater the offset, the greater the correction.

[0026] In a preferred embodiment, in order to improve the robustness and safety of the steering control function, calculating the steering wheel force required for correction includes:

[0027] A variety of methods are used to obtain the target steering wheel angle, multiple angles are arbitrated, the most appropriate angle is selected as the control angle, and the steering wheel is controlled after the angle is converted into steering wheel torque to achieve steering control.

[0028] This application provides two methods for calculating the target steering wheel angle and gives an arbitration solution:

[0029] Calculation method 1: The camera recognizes road information and calculates the unbalanced torque received by the vehicle in combination with the driver's steering intention. The vehicle model is used to calculate the target steering wheel angle required to offset the unbalanced steering torque currently received by the vehicle.

[0030] Calculation method 2: The camera can calculate the deviation angle of the camera position (the camera can detect the longitudinal and lateral vehicle speeds, and can calculate the angle between the two speeds, namely the vehicle deviation angle). The angle of the center of mass position is obtained by performing a coordinate transformation with the vehicle's center of mass position as the origin. The angular acceleration is obtained by taking the second-order derivative of the deviation angle after the coordinate transformation. The angular acceleration is multiplied by the vehicle's moment of inertia to obtain the yaw torque. The steering wheel angle required to offset the yaw torque is then calculated using the vehicle model.

[0031] The two steering wheel angles for controlling the steering wheel obtained by the above methods 1 and 2 are arbitrated. To ensure safety, the larger of the two angles is taken as the steering wheel angle value for control, and then the secondary angle value is converted into a steering wheel torque to control the steering of the steering wheel.

[0032] Furthermore, if an exception occurs in either method 1 or method 2, and only one of them can obtain the steering wheel angle, then the steering wheel angle of the other method will be used for control; if the angle obtained by the camera in method 2 is not available, the angle obtained by method 1 will be used for steering wheel control. Conversely, if the calculation in method 1 is not available, the angle calculated in method 2 will be used for control. The main purpose of the present application to use a dual calculation method to obtain the steering wheel steering angle and then conduct arbitration is to increase the robustness and safety of the function through the camera.

[0033] The present application also provides a car, which integrates the above-mentioned steering control method for assisting vehicle stability, thereby achieving stable operation control of the vehicle.

[0034] The present invention provides a steering control method for assisting vehicle stability. When the function is turned on, the vehicle's driving direction is judged. Only when the driving direction is judged to be the forward direction, the function is allowed to be triggered. During this process, the wheel speed, vehicle speed, yaw angular velocity, lateral acceleration, longitudinal acceleration, road slope, driver-requested braking force, wheel-end torque, etc. are also monitored. When the monitoring result determines that the function is activated, the steering wheel force that needs to be corrected is calculated through the current vehicle state, and the direction is corrected after the force is superimposed on the steering system, so that the vehicle continues to maintain the driving trajectory before the function is triggered. The method can effectively maintain the dynamic stability of the vehicle and improve the riding experience and driving safety.

[0035] The present invention aims at a steering control method for assisting vehicle stability, comprising:

[0036] Step 1: When the vehicle is driving, first determine the direction of the vehicle, determine the wheel speed, vehicle speed, yaw rate, lateral acceleration, longitudinal acceleration, road slope, driver-requested braking force, wheel-end torque, etc. for monitoring;

[0037] Step 2: When the vehicle is moving forward, and through the various parameters in step 1, determine whether the vehicle meets the requirements for triggering the function;

[0038] Step 3: Enter this function. The force acting on the steering wheel is calculated based on vehicle speed, deceleration, wheel-end torque, steering wheel angle, and other parameters to ensure that the vehicle's current operating condition follows the driver's intended driving trajectory. The additional auxiliary force required is calculated and adjusted in real time. The force is calculated mainly by calculating the unbalanced steering torque of the entire vehicle through the wheel-end torque, and the target steering wheel angle required to offset the unbalanced steering torque currently suffered by the entire vehicle is calculated through the vehicle model, and converted into steering wheel torque.

[0039] Step 4: This additional auxiliary force is added to the original steering wheel force and then output to the steering wheel end to keep the vehicle running stably;

[0040] Step 5: If the driver intervenes during the operation of the function, the system will monitor the driver's hand force. When it exceeds the threshold value for a certain period of time, the function will exit and respond to the driver's intention first.

[0041] In step 1, the vehicle driving direction may be determined by a gear position signal or by a sensor other than a wheel speed sensor;

[0042] The vehicle operating conditions in step 3 include but are not limited to emergency braking, rapid acceleration, understeering, oversteering and other operating conditions in which the vehicle deflects due to inconsistency in the road adhesion coefficient.

[0043] The unbalanced force on the vehicle in step three can also be detected by the camera using road information and combined with the driver's steering intention to calculate the unbalanced torque received by the vehicle.

[0044] This method does not add additional hardware equipment to the vehicle system, does not increase hardware costs, and is environmentally friendly and energy-saving. During the operation of this function, no obvious mechanical vibration and noise will be generated; this method can effectively maintain the dynamic stability of the vehicle and improve the riding experience and driving safety.

[0045] Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, they are all within the protection scope of the present invention.

Claims

1. A steering control method for assisting vehicle stability, characterized in that: After the triggering conditions and activation conditions are met, the required corrected steering wheel force is calculated according to the current vehicle state, and the calculated corrected steering wheel force is added to the steering system to perform correction control on the direction of the steering system.

2. A steering control method for assisting vehicle stability as claimed in claim 1, characterized in that: The trigger condition is that the vehicle is traveling in the forward direction.

3. A steering control method for assisting vehicle stability as claimed in claim 1, characterized in that: Based on the vehicle's wheel speed, vehicle speed, yaw rate, lateral acceleration, longitudinal acceleration, road slope, driver-requested braking force, wheel-end torque and other monitoring parameters, it is determined whether the activation conditions are met.

4. A steering control method for assisting vehicle stability as claimed in claim 1, characterized in that: Calculating the steering wheel force required for correction includes: calculating the unbalanced steering torque of the whole vehicle through the wheel end torque, calculating the steering wheel target angle required to offset the unbalanced steering torque currently applied to the whole vehicle through the whole vehicle model, and converting it into steering wheel torque.

5. A steering control method for assisting vehicle stability as claimed in claim 4, characterized in that: The force acting on the steering wheel is the additional auxiliary force required to ensure that the vehicle's current operating condition follows the driving trajectory intended by the driver, calculated based on parameters such as vehicle speed, deceleration, wheel-end torque, and steering wheel angle.

6. A steering control method for assisting vehicle stability according to any one of claims 1 to 6, characterized in that: After the trigger conditions and activation conditions are met, if it is detected that the driver's hand force is greater than the set threshold and lasts for the set time, the steering control corresponding to the driver's hand force will be responded to first.

7. A steering control method for assisting vehicle stability as claimed in claim 2, characterized in that: The vehicle's driving direction is determined by the gear position signal detected by the gear position sensor or the wheel speed signal detected by the wheel speed sensor.

8. A steering control method for assisting vehicle stability as claimed in claim 1, characterized in that: Calculating the steering wheel force that needs to be corrected includes: recognizing road information through a camera, calculating the unbalanced torque received by the entire vehicle in combination with the driver's steering intention, calculating the target steering wheel angle required to offset the unbalanced steering torque currently received by the entire vehicle through a vehicle model, and converting it into a steering wheel torque.

9. A car, characterized in that: The vehicle is integrated with a steering control method for assisting vehicle stability as described in any one of claims 1-8.

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