动力学与瞬时转向中心求解下的4WIS车辆的转向控制方法

Steering Control Method of Four Wheel Independent Steering Vehicle Based on Dynamics and Instantaneous Center of Rotation Solver

为了提高四轮独立转向(4WIS)车辆的转向控制性能,建立4WIS车辆的二自由度动力学模型,求解4个车轮与参考轮之间的转向角关系。在车辆坐标系中建立车轮的运动学模型,通过对车辆瞬时转向中心(ICR)的求解得出各车轮的实时运动学误差表达式,在此基础上提出了一种"动力学-运动学"复合控制策略:依据动力学计算,得出4个车轮的转向角与参考轮之间的约束关系,通过构建网络控制系统,各车轮同时跟踪目标运动轨迹,提高转向控制系统的响应速度;实时运动学误差将各车轮转向角进行虚拟连接,4个车轮协同运动提高了转向控制的平稳性与鲁棒性。仿真结果表明,该控制策略对各车轮进行协调控制,使车辆运动实时满足动力学与运动学要求,具有运算简单、响应速度快、鲁棒性强等特点。最后通过实车实验验证了控制策略的有效性。

In order to improve the steering control performance of four wheels independent steering （4WIS） vehicle, a two-degree of freedom dynamics model of 4WIS vehicle is established and the angle relationship between the four wheels and reference wheel is solved. The kinematics model of four wheels is built in the vehicle coordinate system, and the real-time kinematics error is obtained by solving the instantaneous center of rotation （ICR） of vehicle. Based on these models, a kind strategy named dynamics and kinematics compound control is proposed, the constraint relationship of steering angle between four wheels and reference wheel is got according to the dynamics calculation, through the network control system each wheel tracking the target trajectory independently and simultaneously, so the response speed of the steering control system is improved. The virtual connection of each wheel steering angle is established by real-time kinematical error, so the stability and robustness of steering control is improved by four wheels real-time coordinated motion. The simulation results show that vehicle dynamics requirements are met through the coordination control of wheels. At last, the experimental results show that the control strategy is effective.