Research On Intelligent Vehicle Lane Change Trajectory Planning And Tracking Control Under Structured Roads

Changing lanes is one of the most common driving methods in daily driving behavior,but it is also one of the main causes of some traffic accidents.With the continuous development of autonomous driving technology,the occurrence of traffic accidents can be effectively reduced.Therefore,in order to improve the safety of vehicles in the process of lane change,this paper studies the trajectory planning and motion control of autonomous vehicles in the structured road environment,and the main research contents are as follows:(1)Firstly,the lane changing environment under the structured road is introduced,and the common coordinate system of autonomous driving is explained.Secondly,the safety distance between the vehicle and the surrounding environment vehicles is established,the influencing factors of lane change are analyzed,and the lane change decision algorithm based on fuzzy logical reasoning is completed.(2)In lane change trajectory planning,the trajectory planning problem is transformed into two dimensions: path planning and speed planning.In the path planning,the end point of lane change and the control point selection mechanism are established,and the B-spline curve is used as the lane change model to generate the lane change path,and design the objective function and select the optimal path.In speed planning,the obstacle vehicle motion state is projected to the S-T coordinate system,the dynamic programming algorithm is used to search the speed curve,and the objective function is established to select the optimal speed,and then the five-degree polynomial is used to perform quadratic planning processing on the velocity curve,and finally a smooth lane change trajectory curve that satisfies the kinematic constraints of the vehicle is obtained.(3)Aiming at the problem of lane change trajectory tracking control,the lateral control strategy adopts the vehicle two-degree-of-freedom dynamic model,establishes a lateral error model according to the relationship between the vehicle projection point and the trajectory reference point,and uses a linear secondary regulator(LQR)for lateral position tracking.In terms of longitudinal control strategy,based on the PID control method,the speed and longitudinal position are controlled,and an offline power calibration table is established to convert the vehicle acceleration and deceleration information into throttle/brake signal,and finally realize horizontal and longitudinal layered control.(4)Build a joint simulation platform between Matlab/Simulink and Carsim,simulation verification of straights and curved conditions.The simulation results show that under the conditions of straight and curved driving,the proposed algorithm can complete the task of changing lanes and ensure the driving stability of the vehicle.