A Predictive Control Method For Active Obstacle Avoidance Of Vehicles Considering Transient Characteristics Of Tire Forces

With the increase in the number of vehicles,in order to cope with more and more severe traffic pressure and more and more traffic accidents,autonomous driving technology has been studied by many academic institutions at home and abroad.Among the many technologies of vehicle automatic driving,vehicle active obstacle avoidance technology is particularly important for the safe driving of vehicles.This paper focuses on the intelligent vehicle active obstacle avoidance technology and gives corresponding control strategies for different application scenarios by considering the tire force transient characteristics and ensuring the safety of the vehicle’s movement during obstacle avoidance.The thesis first builds tire steady-state and transient models.Through analyzing and researching the vehicle tire transient characteristics and the vehicle motion state,a vehicle dynamic model describing tire transient characteristics is established.On this basis,the longitudinal control of the vehicle during obstacle avoidance is mainly based on the restriction of the vehicle speed on the stability of the vehicle movement and the maintenance of the longitudinal speed of the vehicle during the lane change process.The longitudinal PID control is used to achieve the desired longitudinal speed of the vehicle.For vehicle lateral control during obstacle avoidance,a combination of vehicle tracking performance indicators and obstacle avoidance penalty functions is used to describe obstacle avoidance trajectory planning and trajectory tracking problems in a unified manner,and an integrated vehicle obstacle avoidance control strategy based on model predictive control is presented;In order to improve the tracking performance of the global static reference trajectory during the vehicle obstacle avoidance process and increase the calculation speed of the obstacle avoidance control by adding a local obstacle avoidance trajectory planning layer.Thus,a smooth transition of the vehicle’s obstacle avoidance trajectory is achieved,and the calculation efficiency is improved.Further,for a smart car with a global obstacle avoidance trajectory planned based on environmental information,a trajectory tracking control strategy based on model predictive control is given.Finally,through the joint simulation and analysis of MATLAB/Simulink and Carsim under various working conditions,the effectiveness of the proposed methods is verified.