Study On Motion Plan And Motion Control Method Of Intelligent Driving Vehicle

Perception plan&decision&control and vehicle electric control are the three key technologies of intelligent driving vehicle.The study on motion plan and motion control method of this paper is the core content of the plan&decision&control layer of intelligent driving vehicle.During the development of intelligent vehicle,there still exist many motion plan and motion control issues.The selected motion plan method is directly related to the intelligent level of the whole vehicle,and the smoothness of the planed track will directly influence driving safety and passenger comfort.The complexity and accuracy of the vehicle model used in the motion control method will influence the response time and track accuracy.Firstly,in order to deal with the speed keeping,following,merging,lane changing driving tasks,a optimal theory based motion plan method is proposed in this paper,which is implemented in the Frenet coordinates.Considering the comfort of the passengers,a concept of jerk is raised,lateral and longitudinal trajectories are calculated separately and summed with different weights.SAT（Separating Axis Theorem）is used in collision checking of these trajectories after which the final optimal motion trajectory is calculated.Furthermore,different cost functions are defined considering the non-holonomic constraints of vehicle dynamics.The longitudinal trajectory is also calculated in different conditions,including velocity keeping and following,merging,stopping.Secondly,in order to track the desired trajectory from the motion plan algorithm,a dynamic model of intelligent driving vehicle is modeled,on basis of which a MPC（model predictive control）and LQR（linear quadratic regulator）based motion control method is proposed.To eliminate the steady track error,a feed-forward termd_FF is added to the outputted steering angle.The torque input of EPS is calculated based on this steering angle using PID control method.Lastly,the build process of an intelligent driving vehicle test platform is introduced taken the case of intelligent driving prototype of Brilliance Auto,including the whole vehicle plan,SW&HW components,and the working principle of some key sub-modules.After that a test method of intelligent driving vehicle is proposed,the analysis of the test result showed that the designed motion plan and motion control method is of good control effect,real-time which can meet the real engineering requirements.