基于线性二次型调节器的四轮转向与分布式集成控制方法

Steering four-wheel distributed integrated control method based on LQR

本文基于线性二次型调节器,集成四轮转向和直接横摆力矩控制设计了一种车辆稳定控制器,实现协同控制策略的创新。该控制系统采用分层结构,上层为基于线性二次型调节器的横摆力矩决策层,下层为驱动力分配层。上层控制器采用迭代法实时求解黎卡提方程得到后轮转角与附加横摆力矩,以完成对质心侧偏角、横摆角速度的优化;下层控制器采用平均分配与序列二次规划两种分配方法,对求得的纵向力与附加横摆力矩进行四轮转矩分配。为了验证控制器的有效性,采用前轮转角阶跃、正弦两种工况对其进行仿真及实车试验。结果表明:该控制器能够使车辆质心侧偏角、横摆角速度较好地追踪理想值,车辆稳定性得到了提高;同时,序列二次规划法更好地降低了轮胎负荷率并延长了电机控制器的使用寿命。

A vehicle stability controller is designed based on a linear quadratic regulator with integrated four-wheel steering and direct yaw moment control providing new collaborative control strategies.The control system adopts a hierarchical structure,with the upper layer being the linear quadratic regulatorbased yaw moment decision layer and the lower layer being the drive force distribution layer.The upper layer controller uses an iterative method to solve the Riccati equation in real time to obtain the rear wheel turning angle and the additional yaw moment to complete the optimization of the side-slip angle of the vehicle and the yaw rate;the lower layer controller uses two distribution methods,namely,average distribution and sequential quadratic programming,to distribute the longitudinal force and the additional yaw moment to the four wheels.In order to verify the effectiveness of the controller,it is simulated and tested in real vehicles using two operating conditions:front wheel stepping angle and sine angle.The results show that the controller can make the side-slip angle of vehicle and yaw rate track the ideal value better,and the vehicle stability is improved;meanwhile,the sequential quadratic programming method reduces the tire loading rate better and increases the service life of the motor controller.