Study On Active Collision Avoidance Motion Planning And Tracking Control Of Intelligent Vehicle

With the increase in car ownership year by year,the number of traffic accidents remains high all year round.Thanks to the improvement of artificial intelligence technology and chip computing power,intelligent vehicle is rapidly moving towards autonomous driving to reduce traffic accidents caused by human factors.As an important link to ensure the safe driving of intelligent vehicle,the collision avoidance system plays a vital role in reducing the accident rate.Aiming at the risk assessment,behavior decisionmaking,trajectory planning and trajectory tracking links in the active collision avoidance system,this paper takes the intelligent vehicle under emergency conditions as the research object,and designs the motion planning method and trajectory tracking control strategy under the structured road to ensure the safety and stability of vehicle traveling.The research work of this paper is as follows:Aiming at the risk assessment,behavior decision-making and trajectory planning problems in the active collision avoidance system,a road model is constructed and coordinate conversion is carried out.Fusion of obstacle motion prediction information,and the predictive risk field based on the three dimensions of the road longitudinal,lateral and time is proposed for risk assessment;consider the constraints of vehicle dynamics,kinematics and curvature,and use dynamic programming methods to make behavior decisions;use polynomial curves and quadratic programming methods to optimize and smooth the decision trajectory.The simulation under the conditions of longitudinal and lateral collision avoidance verifies the reliability of the risk assessment,the rationality of behavior decision-making and the safety of trajectory planning of the motion planning method in the complex road environment.Aiming at the problem of vertical and horizontal trajectory tracking of intelligent vehicle,a linear active disturbance rejection steering controller with expected lateral displacement as input and a longitudinal PID controller with expected speed as input are designed,and the changes in the steering controller parameters of the controlled vehicle are analyzed.The response characteristics below clarify the parameter tuning law of the steering controller.The simulation results under various working conditions show that the steering wheel angle control is mainly provided by the disturbance compensation value,and the trajectory tracking controller has good adaptability and tracking accuracy at different speeds and different road adhesion coefficients.In order to verify the effectiveness of the proposed motion planning method and trajectory tracking controller in joint operation,a joint simulation platform based on Carsim and MATLAB/Simulink is built.The static dangerous conditions on the S-shaped road and the dynamic dangerous conditions of the high-speed road off-ramp are designed,and the comprehensive performance under the two iterative methods of reset error and retention error are compared and analyzed.The simulation results show that the algorithms can plan a safe and reasonable smooth trajectory and track the desired trajectory more accurately to achieve active collision avoidance;the iterative method of resetting error has small lateral tracking error,large speed error,and large steering wheel angle fluctuations.The result of retention error is just the opposite.