基于Tube MPC的多轴重型车辆全轮转向路径跟踪策略

Path Tracking Strategy for All-Wheel Steering of Multi-axle Heavy-Duty Vehicles Based on Tube MPC

本文中为具有智能驾驶功能的五轴重型车辆提出一种基于鲁棒不变集的模型预测控制(Tube MPC)的全轮转向路径跟踪策略。首先提出了基于第1桥和第5桥转角控制的全轮转向路径跟踪策略,使多轴车的控制更灵活,侧向力响应可实现同步且能得到充分利用。接着控制模型考虑轮胎参数不确定和侧向风产生的有界干扰,采用Tube MPC求解路径跟踪问题。同时采用基于支撑函数计算的简化最小鲁棒正不变集(mRPI)代替了通用的基于Minkowski求和的mRPI运算,有效地节约了mRPI的离线计算时间,也减少了不变集的顶点个数,以保证Tube MPC的在线实现。最后进行硬件在环仿真,验证了所提基于Tube MPC的全轮转向策略对比普通的全轮转向策略具有更高的路径跟踪精度和车辆稳定性,面对未知干扰时有更强的鲁棒性。

An all-wheel steering path tracking strategy based on model predictive control with robust invariant set is proposed for a five-axle heavy-duty vehicle in this paper.Firstly,an all-wheel steering path tracking strategy based on first-axle and fifth-axle steering angle control is put forward to make the multi-axle vehicle more flexible in control,with the lateral force response synchronized and fully utilized.Then with considerations of the uncertainty of tire parameters and the bounded disturbance caused by side-wind in the control model,the Tube MPC is used to solve the path tracking problem.Meanwhile,a simplified minimum robust positively invariant set(mRPI)based on support function calculation is adopted to replace the general Minkowski sum-based mRPI operation,effectively saving the offline computation time of mRPI,reducing the number of vertices in the invariant set,and ensuring the online implementation of Tube MPC.Finally,a hardware-in-the-loop simulation is carried out with a result verifying that the Tube MPC-based all-wheel steering strategy proposed has higher path tracking accuracy and vehicle stability and stronger robustness when facing unknown disturbance,compared with ordinary all-wheel steering strategy.