Research On Vehicle Lane Changing Model Predictive Control Strategy Based On Lateral And Longitudinal Control

The random lane changing behavior of drivers is one of the important reasons threatening road safety and causing traffic jams,but it is difficult to be restricted by laws and regulations.Therefore,it is necessary to analyze the lane changing operation from the perspective of scientific research.And the traffic accidents and property losses caused by lane change can be reduced through in-depth study of autonomous lane change technology.In this paper,the domestic and foreign research on lane changing technology was analyzed firstly.Then according to the analysis of lane changing task,it is divided into three aspects:lane changing decision-making,trajectory planning and trajectory tracking.This paper was unfold according to these three aspects.Firstly,based on the demand and feasibility of lane change,the decision-making model of lane change is established,and it is determined whether to change the lane by the minimum lane change distance under three working conditions.Secondly,according to the analysis of the advantages and disadvantages of several lane changing trajectories based on geometric curve,a suitable quintic polynomial lane changing trajectory model is established.And the change of yaw angle shows that the lane changing trajectory of quintic polynomial is smooth and effective.Thirdly,the trajectory tracking controller is designed based on model predictive control algorithm.For the three segments of predictive model,rolling optimization and feedback regulation of model predictive control,based on the three degree of freedom vehicle dynamics model,the predictive model is established after linearization and discretization.Taking the front wheel angle,sideslip angle of mass center and tire sideslip angle as constraints and the increment of front wheel angle as control variables,the optimization objective function is established and transformed into a standard quadratic programming problem which is easy to solve.By solving the quadratic programming problem,the control increment sequence in the control time domain is obtained,so as to complete the trajectory tracking task.According to the simulation results,it is shown that the designed trajectory tracking controller can ensure the accuracy and stability of trajectory tracking.However,it is found that the vehicle speed has a significant impact on the trajectory tracking results under the constraint conditions.Therefore,the trajectory tracking controller of model predictive control was optimized by combining with speed control,and the trajectory tracking system of integrated speed and direction control was established.Finally,in order to verify the effectiveness of the designed automatic lane changing system,the co-simulation model is established.The simulation results show that the designed lane changing system has strong robustness to vehicle speed and road adhesion.Although in the condition that the vehicle speed increases and the road adhesion coefficient becomes smaller,the dynamic characteristics of the vehicle always remain within the constraint range,and the front wheel angle changes smoothly,which can ensure that the target vehicle changes the lane in time,and track the planned lane change trajectory to drive smoothly to the target lane.