Lane Keeping Control Based On An Improved Artificial Potential Method And Coordination Of AFS/DYC Systems

With the rapid development of vehicle technology,Lane Keeping Assistance System(LKAS)plays a more and more critical role in the field of active safety technology.As one of the core technologies of advanced driving assistance system for intelligent vehicles,LKAS is used to control the vehicle to return to the central line of the road when the danger of lane deviation is detected,or to reduce the lane deviation caused by driver's negligence and fatigue driving.In LKAS,the design of lateral controller plays a vital role in the control effect of lane keeping.Good control strategy and path tracking method can achieve real-time,efficient,reliable and safe lane-keeping effect.In this paper,a lateral controller for lanekeeping is designed based on the artificial potential field method firstly.Considering the influence of vehicle speed on the potential field function,also considering vehicle driving safety and handing stability,the yaw angle change rate adjustment factor is introduced to adjust potential field function.And the proportion of speed influence factor and yaw angle change rate adjustment factors in potential field function is allocated by extension decision.The sliding mode controller is designed for the DOF vehicle dynamics model to obtain the front wheel rotation angle.At the same time,in order to solve the problem of system instability caused by frequently starting up the lane-keeping system,the dynamic threshold of lane-keeping distance deviation and angle deviation is made a fuzzy decision.When the real value of any one of them is greater than its threshold,the system starts;when the real value of both is less than its threshold,the system closes.Secondly,the yaw rate and sideslip angle of the center of mass are taken as the characteristic variables to determine the stability of the vehicle.And the safety boundary of the vehicle is divided.Based on this boundary,a plane rectangular coordinate system is established.The motion state of the vehicle is divided into stable state,transition state from stable to unstable and unstable state.The control weights of active front wheel steering and direct yaw moment are determined according to the driving state parameters of the vehicle.And the controllers are designed separately to realize the coordinated control of the two.Finally,in order to verify the validity of the extended sliding mode controller with yaw angle adjusting factor compared with the improved artificial potential field with only considering the velocity influence factor,and the superiority of the active front wheel steering/direct yaw moment coordinated control over the single steering control,Carsim/Simulink joint simulation is carried out.The transverse controller designed by the stock exchange can improve the overall performance of the lane-keeping system to a certain extent.With the help of the existing laboratory conditions and equipment,the PXI real-time hardware in the loop test is carried out.The results show that the designed lanekeeping lateral controller and active steering/yaw moment coordinated control strategy can not only achieve good lane-keeping effect,but also improve the stability of the system.