Yaw rate control of electric vehicle using steer-by-wire system

Recently electric power steering system has been developed. Steer-by-wire system has big advantages of packaging flexibility, advanced vehicle control system, and superior performance. Steer-by-wire system has no mechanical linkage between the steering gear and the steering column. It is possible to control the steering wheel and the front-wheels steering independently. The active steering which reduce the difference between actual and estimated vehicle yaw rate can be realized. Since the information from the steering wheel is important for the driver to know the road condition, tire force should be fed back to the steering wheel. But unexpected disturbance is better suppressed without affecting to the steering wheel. Based on estimating the vehicle side slip angle from the internal sensor response, the tire self-aligning torque can be estimated. This torque is fed back to the steering wheel so that the driver can know the road condition. In this paper, we propose the method to control the vehicle yaw rate using steer-by-wire system, also disturbance applied to the front tires is suppressed by disturbance observer without affecting to the steering wheel. Numerical simulations are carried out to show the validity of the proposed method.