Research On Lane Changing Assistant System Based On Model Predictive Control

With the development of China's economy,people are pursuing the standard of living and are paying more and more attention to the safety of traffic.As an important part of the vehicle active safety system,the lane changing auxiliary system has always been a hot topic in the field of automotive safety.When the vehicle is in danger of collision,it often needs to be used in the way of braking or changing the path to avoid collision.But when an obstacle or unexpected emergency is suddenly appeared in the near distance of the front of the vehicle,the operation time of the brake obstacle avoidance for the driver is not enough.At this time,it is difficult to play the role by the longitudinal brake obstacle avoidance,and the collision may be avoided by changing the channel.Therefore,it is of great significance to the research of the auxiliary system.First,the vehicle dynamics model and the tire model are built on the basis of the function of the lane changing auxiliary system.On this basis,the simplified results are used as the basic model of model predictive control.Then,the modeling of the steering system is carried out,and then the path planning is carried out according to the constraint conditions of the path in the change process,and the appropriate safety distance model is established as the index of the risk warning for the change of the road.According to the function of lane changing auxiliary system,the control framework of lane changing auxiliary system is established,and the early warning system and lane changing active control system are designed.Among them,the early warning system mainly uses the perceptual layer to detect the situation of the front obstacle,and by virtue of the decision mechanism evaluation index,choose whether to take the active control mode,so as to ensure that the traffic accidents can be avoided when the vehicle meets the risk of collision.In order to avoid obstacle avoidance by braking when the longitudinal braking distance is insufficient in the course of driving,and the traditional control method can not achieve the lack of multi-objective control in the process of changing the path,a multi target control method based on model prediction(MPC)for path tracking is proposed.In order to solve the problem of stability control in the process of changing,the lateral and longitudinal position of the trajectory and the yaw rate are used as the state quantity,the front wheel angle and the additional yaw moment are the control quantity,the expected trajectory is the control target,and the steering and the brake change control strategy is designed.Using CarSim and Matlab simulation platform to set up different working conditions,the lane changing auxiliary system is simulated and verified.Finally,the hardware in the loop and the real vehicle test platform is designed and built,and the effectiveness of the proposed method is verified by the test.