Research On Shared Lateral Control Of Driver Steering Assist System

With the continuous growth of automobile ownership,how to reduce the incidence of traffic accidents and improve the safety of automobiles has become the focus of attention.Meanwhile,driver assistance system as the backbone has been the core of vehicle active safety research.In this paper,the human-machine coordination of lateral control of driver assistance system is studied,and also the lane keeping performance under human-machine co-driving is discussed.The main work done in this paper is as follows:(1)The driver model based on two-point preview is established,and the driver model is integrated with the road-vehicle position model,as to say,driver in the loop,which is used to realize the information interaction between the driver and the steering assist system.At the same time,the model of electric power steering system(EPS)is established,which is to consider the driver's feeling of steering torque feedback and to study the haptic human-machine interaction.At last,the global steering assist system model is obtained.(2)The actual demand of the driver for steering assistance is analyzed by considering the torque applied by the driver in real time and the driver state obtained from the upper driver monitoring system.Also,the control law is based on the actual needs of the driver.Simulation verifies that the weighting factor can vary with the driver's activity in time,while ensuring the lane-keeping performance,and the coordination of human and machine is improved.Also,the EPS active steering control strategy has been made so that the steering system can provide assistance in real time.(3)In order to deal with the variable parameter system,which includes the timevaring driver activity varible and a large variation range of vehicle speed,T-S fuzzy control approach has been chosen.After the number of prerequisite variables is determined,the amount of subsystems is simplified by first-order Taylor,then the four subsystems related to speed and weighting factor are obtained.The parallel distribution compensation method is adopted(PDC)during the controller design process.The optimal control theory and state feedback control are also discussed in this paper.(4)Simulations are conducted using MATLAB/Simulink platform.The performance of the driver steering assist system under different working conditions is tested,and the vehicle stability,human-machine coordination and lane keeping performance are also analyzed and verified.The simulation results show that the assist system can assist the driver to ensure the stability of the vehicle under the lateral wind resistance.When the driver is in good condition,the steering assist system can determine the appropriate assist level according to the change of driver's behavior factor.While in the driver's state fluctuation,the system can take on the vehicle control task in time to ensure the normal driving of the vehicle.In the case of special obstacle avoidance,considering the driver behavior in the loop can deal with the problem of man-machine conflict and change the assist level according to the driver's behavior.