Active Collision Avoidance Control And Simulation Research

The active collision avoidance system of the vehicle is an important guarantee for the safety of the vehicle.In an emergency,the vehicle is decelerated or turned to avoid collision with the preceding vehicle,and the driving safety of the vehicle is improved.As a research object,the front-wheel drive vehicle researches the active collision avoidance system combining three types of collision avoidance modes: longitudinal braking,lanechanging and steering/brake synergy.The main research contents of the thesis are as follows:(1)For the longitudinal braking mode,the Carsim software is used to establish the longitudinal dynamics model,and the vehicle inverse dynamics model is established based on the engine characteristic curve.The vertical braking avoidance control system is divided into two layers by the upper and lower layer control method.The upper layer is based on the fuzzy control theory to design the longitudinal braking control strategy,and the lower layer is based on the PID control theory to realize the real-time feedback of the actual deceleration,through simulation and real vehicle.The road test verified the effectiveness of the longitudinal braking collision avoidance algorithm.(2)For lane-changing mode,the lateral dynamics characteristics of the vehicle lane change process are studied and analyzed,and the vehicle 2-DOF nonlinear dynamic model is established by the classic magic tire model.In order to ensure the continuity of the lane change path of the vehicle,the polynomial interpolation curve planning method is used to plan the lane change route for the vehicle,and the minimum safe collision time model of the vehicle is designed according to the lane change characteristics.The vehicle steering lane change tracking controller based on the model predictive control theory is designed to control the vehicle's steering lane change by controlling the front wheel angle of the vehicle,and to ensure the steering stability of the vehicle in combination with various constraints in the vehicle steering lane change process.The effectiveness of the steering lane avoidance algorithm is verified by simulation.(3)Aiming at the emergency situation that the two methods of longitudinal braking and steering lane change cannot achieve effective collision avoidance,a steering/brake coordinated collision avoidance control system based on model predictive control theory is proposed.The system adopts the upper and lower layer control method,and the upper layer is the path planning controller.According to the current state of the vehicle and the obstacles ahead,the optimal lane changing path and the deceleration curve are planned;the lower layer is the path tracking controller to control the vehicle deceleration and steering.Achieve emergency collision avoidance purposes.The effectiveness of the cooperative collision avoidance algorithm is verified by simulation.(4)For the avoidance mode decision mechanism,based on the characteristics of three collision avoidance methods,the safety collision time TTC model of the collision avoidance system is studied,and the minimum safe braking time model and the minimum safe lane change time model are established,with TTC and relative speed as The decisionmaking mechanism of the design fuzzy avoidance mode is input,and the optimal collision avoidance mode is determined according to the real-time driving state information.