Research On Stability Control And Fault-Tolerant Control Of Four-wheel Steer-by-wire System

Four-wheel steer-by-wire system,combined with the active front wheel steer-by-wire system and the active rear wheel steering system,not only can improve handling performance active front wheel steering system and the active rear wheel steering system,but also play the advantages of active steering system better through the front wheel and rear wheel two active inputs.In this paper,the stability control and fault-tolerant control of the four-wheel steer-by-wire system are studied.First,four-wheel steer-by-wire system model,four wheel steering vehicle model and the driver model are established to be applied to the simulation of vehicle steering performance and controller design.Then,based on fixed yaw rate gain and fixed lateral acceleration gain,a two degree of freedom reference model is designed for stability control.Based on the theory of ? control,the stability control of four wheel steering system is researched considering the uncertainty of tire's nonlinear parameters and the speed of driving process.Finally,considering the important sensors in the stability control of four-wheel steer-by-wire system,the states estimation are carried out based on the unscented kalman filtering algorithm,and the hardware and software redundancy system of the relevant sensors is designed.Through the research on the above problems,it can provide theoretical basis and technical support for the design and development of four-wheel steer-by-wire system.