The optimization of electric power assisted steering to improve vehicle performance

Abstract To investigate the e ects of electric power assisted steering (EPAS) on a vehicle's steering performance, this paper explicitly proposes several indices, such as steering sensitivity and road feel, for evaluation of steering performance. Then a single-track car model with lateral and yaw movement is considered and an EPAS model is built. The mathematical expressions for the steering performance indices are deduced and a stability criterion is established by integrated analysis of the vehicle's dynamics and the EPAS dynamics. By means of frequency domain analysis, the e ect of each parameter of EPAS on steering performance indices is analysed. Finally, an optimizing model used to improve these steering indices is put forward and the result is given.