Study On Lane Keeping H_∞ Robust Control Of Autonomous Vehicles

The lane-keeping is an important function of autonomous vehicles.In the process of lane keeping control,the uncertainty of the road curvature and the error of the navigation system can be considered as the external disturbance.Larger disturbance will lead to instability of the lane keeping control for autonomous vehicles,and the lateral position error and yaw angle error may out of control during the process.So the study of the lane-keeping control method with robust stability is of great significance to realize the automatic driving functions of the vehicle..In this paper,H_∞robust control theory has been used to study the lane-keeping control of autonomous vehicles.First of all,the necessity of using H_∞robust control theory in the lane-keeping control is explained and the maximum road curvature disturbance the vehicle will confront at different vehicle speeds is defined.A two-degree-of-freedom vehicle dynamic model based on the road error has been established.The influence which the longitudinal velocity takes on the lane-tracking control has been analyzed and a method for discretizing the speed parameters and designing different controller has been proposed.Secondly,the H_∞state feedback control and the LMI(Linear Matrix Inequality)method are studied.Based on the vehicle dynamics model,the LMI has been established.In order to solve the high-order LMI,a dichotomous-stochastic searching algorithm has been designed.According to this algorithm,a lane keeping H_∞state feedback controller has been solved.At last,the lane-keeping H_∞state feedback controller has been simulated based on the Matlab/Simulink software.Under the different disturbances,this paper studied the step response about the lateral position and the yaw angle and the tracking response of the desired trajectory,the simulation results verify the effectiveness of the H∞state feedback controller and its ability to suppress the system uncertain disturbance.