Rear wheel angle control method capable of improving lane changing comfort of vehicle

Abstract

A rear wheel angle control method capable of improving the lane changing comfort of a vehicle comprises the steps that firstly, when it is recognized that the vehicle changes a lane, an ideal transverse acceleration and an ideal yaw velocity can be calculated and selected by solving a vehicle dynamics matrix equation; therefore, a deviation value is calculated according to the real-time transverse acceleration and yaw velocity of the vehicle, a rear wheel compensation rotation angle feedback value is obtained through a PID control algorithm, and meanwhile, a side deviation compensation angle of a tire is calculated according to a rear wheel side slip angle. Finally, the target control angle of the rear wheel can be calculated according to the rear wheel rotation angle, the rear wheel compensation rotation angle feedback value and the side deviation compensation angle of the tire. According to the method, the yaw velocity and the transverse acceleration are fully reduced in the calculation process, and the comfort of the automobile in the lane changing process can be effectively improved.

Description

Technical Field

[0001] The present invention relates to a field of rear wheel control, and in particular to a rear wheel angle control method capable of improving vehicle lane-changing comfort. Background Art

[0002] With the rapid development of intelligent driving technology, the role of the driver has undergone a fundamental transformation, shifting from traditional driver to passenger. After ensuring the stability and safety of intelligent vehicles, vehicle comfort has gradually become a goal that people pursue. Therefore, evaluations of intelligent vehicle comfort will no longer be limited to interior design, chassis design, and handling capabilities. Evaluations of vehicle comfort will focus more on whether intelligent vehicles can provide passengers with a comfortable riding experience and facilitate non-driving tasks.

[0003] Intelligent driving and four-wheel steering technologies continue to advance, but relatively little research has been conducted on their combined applications in lane-changing processes. While demand for improved vehicle ride comfort continues to grow, lane-changing operations can negatively impact ride comfort. Current lane-changing control strategies utilize vehicle turning methods, with one lane change equivalent to two turns in opposite directions. Generally, the lane-changing process in a typical vehicle generates two lateral accelerations in different directions. These accelerations in both directions within a short period of time can cause the driver and passengers to deviate from their original seating positions, impacting ride safety and comfort. Therefore, it is necessary to reduce the yaw rate and lateral acceleration during lane changes to further improve ride comfort. Summary of the Invention

[0004] The purpose of the present invention is to provide a rear wheel angle control method that can improve the lane changing comfort of a vehicle, reduce the yaw angular velocity and lateral acceleration of the vehicle when changing lanes, and improve the comfort of the vehicle during the lane changing process.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a rear wheel angle control method capable of improving vehicle lane changing comfort, comprising the following steps: S1. Obtain vehicle information through sensing equipment and navigation system, and then recognize through vehicle controller that the vehicle is changing lanes; S2. Establish a two-degree-of-freedom model for the vehicle. The differential equation for the two-degree-of-freedom vehicle motion is: ...Formula (1); In formula (1), is the front wheel cornering stiffness, is the front wheel cornering stiffness, is the sideslip angle at the center of mass, is the distance from the center of mass to the front axle, is the distance from the center of mass to the front axle, is the yaw angular velocity, is the front wheel turning angle, is the rear wheel turning angle, is the longitudinal velocity, is the lateral acceleration of the center of mass, is the moment of inertia of the vehicle around the z axis, m is the mass of the vehicle, and a is the lateral acceleration; S3, let the yaw angular velocity =0, and then according to formula (1) the lateral acceleration is: ...Formula (2); In formula (2), is the lateral velocity; S4. Substituting into formula (2), we can get The vehicle dynamics matrix equation is: ; ; ; ; Solve the equation to obtain multiple values of lateral acceleration a and multiple yaw angular velocities The ideal lateral acceleration a is then obtained d and the ideal yaw rate : ,and ; ,and ; S5. Calculate vehicle lateral acceleration and yaw rate deviation : , a0 is the real-time lateral acceleration; , is the real-time yaw angular velocity; S6. Calculate the rear wheel compensation angle feedback value : ...Formula (3); In formula (3), is the PID control proportional coefficient, is the PID control integral coefficient, is the PID control differential coefficient; S7. Calculate rear wheel slip angle : ; Then calculate the tire's side slip compensation angle : ...Formula (4); In formula (4), P is the compensation percentage, ranging from 5% to 15%; S8: Calculate the target turning angle value for rear wheel angle control : ; The vehicle controller calculates the target turning angle value in real time The rear wheels of the vehicle are controlled until the vehicle completes the lane change.

[0006] Preferably, the sensing equipment includes an inertial measurement unit IMU, a vehicle-mounted camera, a millimeter-wave radar or a lidar, which monitors the vehicle's driving trajectory through the global navigation satellite system GNSS, detects lane lines through the vehicle-mounted camera, millimeter-wave radar or a lidar, and collects the vehicle's real-time lateral acceleration, real-time yaw angular velocity and real-time center of mass sideslip angle through the inertial measurement unit IMU.

[0007] According to the above technical solution, the beneficial effects of the present invention are: When the control method of the present invention identifies a vehicle lane change, it solves the vehicle dynamics matrix equation to calculate and select the ideal lateral acceleration and yaw rate. This method then calculates a deviation value based on the vehicle's real-time lateral acceleration and yaw rate. A PID control algorithm is then used to obtain a rear wheel compensation angle feedback value. Simultaneously, the tire's slip compensation angle is calculated based on the rear wheel slip angle. Ultimately, the target rear wheel control angle is calculated based on the rear wheel angle, the rear wheel compensation angle feedback value, and the tire's slip compensation angle. This method significantly reduces the yaw rate and lateral acceleration during the calculation process, effectively improving the vehicle's comfort during lane changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram of the intelligent driving vehicle network architecture of an embodiment. DETAILED DESCRIPTION

[0009] This embodiment provides a rear wheel angle control method capable of improving vehicle lane-changing comfort, comprising the following steps: S1. Obtain vehicle information through sensing equipment and a navigation system, and then recognize through a vehicle controller that the vehicle is changing lanes.

[0010] The sensing equipment includes an inertial measurement unit (IMU), an on-board camera, a millimeter-wave radar or a lidar. The vehicle's driving trajectory is monitored through the global navigation satellite system (GNSS), and the lane lines are detected through the on-board camera, millimeter-wave radar or a lidar. The vehicle's real-time lateral acceleration, real-time yaw angular velocity and real-time center of mass sideslip angle are collected through the inertial measurement unit (IMU).

[0011] S2. Establish a two-degree-of-freedom model for the vehicle. The differential equation for the two-degree-of-freedom vehicle motion is: ......Formula (1).

[0012] In formula (1), is the front wheel cornering stiffness, is the front wheel cornering stiffness, is the sideslip angle at the center of mass, is the distance from the center of mass to the front axle, is the distance from the center of mass to the front axle, is the yaw angular velocity, is the front wheel turning angle, is the rear wheel turning angle, is the longitudinal velocity, is the lateral acceleration of the center of mass, is the moment of inertia of the vehicle around the z-axis, m is the mass of the vehicle, and a is the lateral acceleration.

[0013] 、 、 and m are the basic parameters of the car, and Can be obtained through the Magic Tire formula, and It can be obtained through the angle sensor on the tire. It can be obtained through vehicle sensors. 、 , a and The data collected by the inertial measurement unit (IMU) is combined with the calculation of the vehicle controller.

[0014] S3, let the yaw angular velocity =0, and then according to formula (1) the lateral acceleration is: ...Formula (2); In formula (2), is the lateral velocity, It can be obtained through vehicle sensors.

[0015] S4. Substituting into formula (2), we can get The vehicle dynamics matrix equation is: ; ; ; .

[0016] Solve the equation to obtain multiple values of lateral acceleration a and multiple yaw angular velocities The ideal lateral acceleration a is then obtained d and the ideal yaw rate : ,and ; ,and .

[0017] S5. Calculate vehicle lateral acceleration and yaw rate deviation : , a0 is the real-time lateral acceleration; , is the real-time yaw rate.

[0018] S6. Calculate the rear wheel compensation angle feedback value : ...Formula (3); In formula (3), is the PID control proportional coefficient, is the PID control integral coefficient, is the PID control differential coefficient.

[0019] S7. Calculate rear wheel slip angle : .

[0020] Then calculate the tire's side slip compensation angle : Formula (4); In formula (4), P is the compensation percentage, which ranges from 5% to 15%.

[0021] S8: Calculate the target turning angle value for rear wheel angle control : .

[0022] The vehicle controller calculates the target turning angle value in real time The rear wheels of the vehicle are controlled until the vehicle completes the lane change.

[0023] This embodiment also provides a vehicle network architecture with intelligent driving and four-wheel steering that can implement the control method of the present invention, such as Figure 1 As shown in the figure, the vehicle motion controller (C-MCU) receives data from the remote driving unit (RDU) and vehicle control unit (VCU) via the CAN bus. The MCU executes user-defined driving, braking, and steering control algorithms and sends corresponding control instructions to the VCU to control wheel rotation, torque, and yaw angle. In this experimental platform, the MCU is connected to the vehicle VCU's external CAN bus and receives RDU information forwarded by the VCU. Using user-defined algorithms, the MCU calculates the yaw angle and driving torque of the four wheels, thereby achieving lateral and longitudinal control of the vehicle.

[0024] Figure 1 The intelligent driving controller (VE-IDU) in the vehicle control unit (VCU) uses Ethernet connectivity. The VE-IDU receives raw signals from intelligent driving sensors such as cameras, lidar, and millimeter-wave radar via the VCU's wired Ethernet connection. It then runs environmental perception and path planning algorithms and outputs steering wheel angle requirements, accelerator pedal, and brake pedal opening requirements, which are then sent to the VCU via wired Ethernet. The VCU then forwards this information to the RDU via the wireless network. The RDU outputs steering wheel control torque to rotate the steering wheel and transmits the steering wheel angle and other information collected by the RDU to the VCU via the wireless network, enabling intelligent driving and human-machine collaborative driving. As the core component of the vehicle control system, the vehicle controller (VCU) coordinates data acquisition from various sensors and control of actuators. It connects sensors and actuators via different buses and converts their status data into unified CAN and Ethernet protocol formats, providing users with a unified development interface. In addition to coordinating the work of sensors and actuators, the VCU is responsible for executing basic vehicle control algorithms, including driving, braking, steering, and protection functions, to ensure proper vehicle operation and safety.

Claims

1. A rear wheel angle control method capable of improving vehicle lane-changing comfort, characterized in that: The following steps are involved: S1. Obtain vehicle information through sensing equipment and navigation system, and then recognize through vehicle controller that the vehicle is changing lanes; S2. Establish a two-degree-of-freedom model for the vehicle. The differential equation for the two-degree-of-freedom vehicle motion is: ...Formula (1); In formula (1), is the front wheel cornering stiffness, is the front wheel cornering stiffness, is the sideslip angle at the center of mass, is the distance from the center of mass to the front axle, is the distance from the center of mass to the front axle, is the yaw angular velocity, is the front wheel turning angle, is the rear wheel turning angle, is the longitudinal velocity, is the lateral acceleration of the center of mass, is the moment of inertia of the vehicle around the z axis, m is the mass of the vehicle, and a is the lateral acceleration; S3, let the yaw angular velocity =0, and then according to formula (1) the lateral acceleration is: ...Formula (2); In formula (2), is the lateral velocity; S4. Substituting into formula (2), we can get The vehicle dynamics matrix equation is: ； ； ； ； Solve the equation to obtain multiple values of lateral acceleration a and multiple yaw angular velocities The ideal lateral acceleration a is then obtained d and the ideal yaw rate : ,and ; ,and ; S5. Calculate vehicle lateral acceleration and yaw rate deviation : , a0 is the real-time lateral acceleration; , is the real-time yaw angular velocity; S6. Calculate the rear wheel compensation angle feedback value : ...Formula (3); In formula (3), is the PID control proportional coefficient, is the PID control integral coefficient, is the PID control differential coefficient; S7. Calculate rear wheel slip angle : ； Then calculate the tire's side slip compensation angle : ...Formula (4); In formula (4), P is the compensation percentage, ranging from 5% to 15%; S8: Calculate the target turning angle value for rear wheel angle control : ； The vehicle controller calculates the target turning angle value in real time The rear wheels of the vehicle are controlled until the vehicle completes the lane change.

2. The rear wheel angle control method for improving vehicle lane-changing comfort according to claim 1, characterized in that: The sensing equipment includes an inertial measurement unit (IMU), an on-board camera, a millimeter-wave radar or a lidar. The vehicle's driving trajectory is monitored through the global navigation satellite system (GNSS), and the lane lines are detected through the on-board camera, millimeter-wave radar or a lidar. The vehicle's real-time lateral acceleration, real-time yaw angular velocity and real-time center of mass sideslip angle are collected through the inertial measurement unit (IMU).

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