Research On Vehicle Active Collision Avoidance Strategy

In recent years,due to the rapid development of society and the improvement of economic benefits,the number of vehicle across the country is increasing day by day,and the road safety problem caused by cars has become a major public hazard in the current era.Active collision avoidance control system,as an active safety technology of vehicle,will have a rear-end collision between the rear car and the front car and the driver does not react in time.It makes independent decisions on collision avoidance and actively controls the vehicle to brake down or change lanes to avoid collision accidents,which is helpful for solving road safety problems and ensuring driving safety.It is of strategic significance to promote the development of vehicle intelligence.Therefore,this paper studies the vehicle active collision avoidance technology,designs the active collision avoidance control system,and carries out joint simulation with Carsim/Simulink platform to verify the effectiveness of the active collision avoidance system.The main research contents of this paper are as follows:1.The extended Kalman filter is used to estimate the pavement adhesion coefficient.Firstly,the theory and algorithm of Kalman filter are briefly introduced.Then,aiming at the problem that Kalman filter algorithm can only be used for linear system,the pavement adhesion coefficient estimation algorithm based on extended Kalman filter is designed by studying the theory of extended Kalman filter and using Dugoff tire model.And by Car Sim/Simulink platform co-simulation,the accuracy of the algorithm is verified,which lays a foundation for the future research of vehicle active collision avoidance system.2.Design of vehicle longitudinal braking collision avoidance system based on fuzzy control.Firstly,the vehicle deceleration braking is analyzed,and the longitudinal braking safety distance model is designed according to the three common driving states of stationary,uniform and even deceleration of the vehicle in front,as well as the road adhesion coefficient and the driver’s operating characteristics.Based on this distance model,the layered control is selected,and the vehicle dynamics system is controlled through the longitudinal inverse dynamics model of the vehicle.Realize the braking deceleration of the car,and keep a safe distance with the front car.3.Design of vehicle steering lane change collision avoidance system based on model predictive control.Considering that collision avoidance is difficult to be achieved by longitudinal braking alone and that the traditional control method cannot solve the constrained optimal control problem in the process of lane change and collision avoidance,this paper designs a trajectory tracking controller based on the model predictive control theory to realize lane change and collision avoidance.Firstly,the controller design is based on the simplified three-degree-of-freedom model of the vehicle,and the collision avoidance trajectory is the single shift line fitted by the fifth degree polynomial.The model predictive control theory is used to change the optimal control problem in the process of lane change into a quadratic function with constraints for solving.The influence of different controller parameters on trajectory tracking is also studied,and then the comprehensive evaluation index of path tracking performance is designed.Select the optimal time domain parameters.4.Simulation verification of vehicle active collision avoidance system.By Simulink and Carsim co-simulation,the longitudinal braking collision avoidance system and steering lane change collision avoidance system are simulated and verified according to the driving conditions of the front vehicle respectively under the road surface with 0.8 high adhesion and 0.3 low adhesion.The results show that the designed longitudinal braking system can achieve the purpose of slowing down and maintaining vehicle distance.Similarly,the steering lane change system can control the desired collision avoidance trajectory of vehicle tracking,and avoid rear-end collision by steering lane change,and has good handling stability in the process of lane change.