Control Strategy of the Vehicle's Active Steer by Wire

Zhang, Q.; Lin, W.; Wang, Y.; Wu, X., and Luo, Y., 2020. Control strategy of the vehicle's active steer by wire. In: Yang, Y.; Mi, C.; Zhao, L., and Lam, S. (eds.), Global Topics and New Trends in Coastal Research: Port, Coastal and Ocean Engineering. Journal of Coastal Research, Special Issue No. 103, pp. 355–360. Coconut Creek (Florida), ISSN 0749-0208.The Steer-By-Wire (SBW) system is free from the constraints of mechanical structure. Whether the system can work normally depends on the correctness of the control strategy. Therefore, this paper will study the control strategy of active steering by wire, which includes the design of ideal variable angle ratio control and active front wheel steering controller. Feed-forward control of ideal variable angle transmission ratio was determined based on constant yaw angular velocity gain. The sliding mode variable structure control theory is adopted. Based on the yaw rate deviation, the integral sliding surface is constructed, and the control strategy of equivalent and switching control is designed and active front wheel steering controller is completed. Through feedback control, the active control of the vehicle's front wheel angle is achieved, which improves the stability of the vehicle. Finally, through the typical test conditions, the designed control strategy was simulated and verified, and compared with the simulation results of uncontrolled vehicles. The results showed that the sliding mode controller of active SBW front wheel designed by yaw angular velocity feedback under the ideal variable transmission ratio can run stably under any working conditions and achieve good track following ability.