Research On Trajectory Planning And Tracking Control Of Vehicle Active Lane Change

With the increase of car ownership,the road traffic environment is becoming more and more complex,and the driving burden borne by car drivers is increasingly heavy.Lane changing is a common but dangerous driving condition in the driving of a car.In order to reduce the decision-making and operation errors of drivers in the process of lane change and improve the safety of lane change,this thesis studies the planning and control strategy of the active lane changing system.Firstly,this thesis describes the research status of active lane change system at home and abroad,and summarizes the main research content of this paper.According to the research needs,the dynamic model of the controlled vehicle and the relationship model of vehicle road position are built,and the longitudinal safety distance between the controlled vehicle and the surrounding traffic participating vehicles is analyzed.It laid the foundation for the follow-up study.In order to solve the problem that the traditional lane changing trajectory planning method does not consider the state change of vehicles in front of it,a dynamic lane changing trajectory planning strategy is proposed.Firstly,considering the efficiency and comfort of lane change,the reference track of lane change is calculated based on the quinquennial polynomial;So as to ensure the safety of lane changing process,the dynamic trajectory planning method combines with the lane changing stability constraint,road boundary constraint and the position constraint affected by the vehicle in front,and turns the trajectory planning problem into a rolling optimization problem,so that the replanned lane change track can adapt to the change of the front vehicle state.Based on Sliding mode control algorithm,the trajectory of dynamic planning is tracked.Through the joint simulation of Car Sim/Simulink,it is verified that the proposed dynamic trajectory planning and tracking control strategy can ensure the safety and maintain the comfort and efficiency of lane changing when the state of the front vehicle changes.In the complex traffic scene,only relying on steering can not achieve the shortage of safe lane change,the vertical and horizontal motion of the car is planned.Firstly,the intention of lane change is analyzed,and the condition of lane change is judged according to the limit range of longitudinal acceleration to ensure driving safety,and the expected longitudinal acceleration and transverse reference quantity are obtained;According to the stability analysis of the vehicle in transverse motion,the yaw rate constraint of the vehicle is established,and the steering wheel angle that can guarantee the constraint is obtained based on MPC algorithm;Finally,a joint simulation is carried out to verify the effectiveness of the proposed lane change decision planning strategy.Finally,on the basis of theoretical research,the hardware in the loop test is carried out for the two different methods based on the horizontal and vertical driving assistance test platform.The experimental results show the effectiveness and feasibility of the two methods.