基于非线性模型预测控制的车辆纵向队列协调控制

Coordinated Control of Vehicular Platooning Based on Nonlinear Model Predictive Control

本文中针对基于分层控制结构的车辆队列上、下层控制缺少联系的问题,提出了车辆队列跟驰与个体车辆动力学稳定性协调控制的思路,其基本思想是在保证队列中个体车辆安全稳定行驶的同时,尽可能实现队列跟驰控制的目标。基于非线性模型预测控制(nonlinear model predictive control,NMPC)方法设计了车辆队列协调控制方案,设计了包括跟驰间距误差、跟驰速度误差以及车速与车轮圆周速度差3个子目标的优化目标函数,将队列跟驰与车辆动力学稳定性的协调控制转化为约束优化控制问题;基于序列二次规划(sequential quadratic programming,SQP)方法进行求解,得到车辆前、后轴的制动/驱动力矩来实现上层决策输出的期望跟驰加速度。基于由3车辆组成的非线性队列模型对控制方案进行了仿真分析,结果表明,所提出的基于NMPC的车辆队列协调控制策略可以在大范围操纵工况下,在保证车辆安全稳定行驶的基础上实现队列的跟驰控制。

For the problem of the lack of connection between the upper and lower control of vehicular platoon based on hierarchical control,this paper puts forward the idea of coordinated control of vehicle platoon following and individual vehicle dynamics stability.The basic idea is to realize the objective of vehicle following control as much as possible while ensuring the safe and stable driving of the individual vehicles.A coordinated control scheme is designed by the nonlinear model predictive control(NMPC)method,and the optimization objective function consisting of three sub-objectives of the spacing error and the velocity error between two adjacent vehicles,and the difference of vehicle speed and wheel circumferential speed is designed.Hence,the coordinated control scheme is transformed into an optimal control problem with constraints,which is solved based on the sequential quadratic programming(SQP)method and the braking/driving torques of the front and rear axles are obtained to achieve the desired following acceleration of the upper decision-making output.The simulation analysis of the proposed control scheme is carried out based on the nonlinear platoon model composed of three vehicles.The results show that the proposed NMPC based coordinated control scheme can well realize vehicle following control while simultaneously ensuring safe and stable driving of the individual vehicle in a broad range of operating conditions.