Research On Vehicle Lane Chaning Control Based On The Minimum Safety Distance

Lane changing of intelligent vehicle is a common but complex behavior, its core issues are planning trajectory model and designing trajectory tracking control system. At present, most researches on the lane changing of intelligent vehicle are focused on the straight road and the constant speed. The purpose of this thesis is based on the minimum safety distance model to study intelligent vehicle changing lane at an accelerating rate on a curve road.In this thesis, according to the yaw movement rule of vehicle, a trajectory planning model for lane changing based on yaw angular acceleration is established, then the model is compared with the model based on lateral acceleration rate. Comparison shows that, the method using the trajectory planning model based on yaw angular acceleration can simplify calculation of lane changing control. The curvature of the road is taken into account, the desired yaw angle and yaw rate model about lane changing is extended from the straight road to the curve road.Based on the minimum safety distance model on straight road, the minimum safety distance model for lane changing on the curve road is built. Comparing with the minimum safety distance model on line road, the validity of minimum safety distance model on the curve road is proved by the joint simulation via MATLAB/Simulink and Carsim software.With the vehicle model about longitudinal and lateral coupled dynamic model, considering the curvature of road and variation of vehicle longitudinal speed, nonsingular terminal sliding mode control system is established. The phase plane method is used to analyze the stability of the control system. The effectiveness about the control law is verified by the simulation. Simulation results show that the yaw angle error and longitudinal displacement error have asymptotic stability.In regard to unknown vehicle parameters, trajectory tracking adaptive control system is established and then the analysis of stability is finished. The results of simulation show that adaptive control system can realize the trajectory tracking control quickly, and make the unknown parameter tend to the actual value. In regard to bounded time-varying vehicle parameters, a quasi-sliding mode control system is established. The results of simulation show that the chattering phenomenon of the sliding mode control system is weakened effectively, and the expected control effect is achieved in the limited time. In regard to the phenomenon of the vehicle sideslip, sliding mode control system based on four-wheel steering lateral dynamics model is established based. Then it is compared with the front wheel steering on the vehicle trajectory tracking position error, comparison shows that four-wheel steering vehicle had a stronger trajectory tracking capability when changing lane on a curve road.