Personalized Steering Feel Design for Steer-by-Wire Systems Based on the Rack Force Estimation

This paper proposes a personalized steering feel model for the steer-by-wire vehicles to reconstruct the haptic feedback during steering motion. Through the investigation of the steering mechanism, the aligning torque obtained via the rack force estimated by the extended disturbance observer and the equivalent friction torque modelled using a hyperbolic tangent function constitute the steering feel model. Also, different mathematical functions are designed to achieve the characteristics of the power assist and the steering feel varying with vehicle speeds. The variable parameters are introduced to design the personalized steering feel and the objective evaluation is employed to evaluate the performance of the proposed model. The hardware-in-the-loop experiment results demonstrate that the designed extended disturbance observer has good rack force estimation performance. Compared with conventional electric power steering systems, the proposed model achieves the same haptic feedback and has the assist effect and the characteristics of steering feel that changes with speed. Furthermore, the personalized steering feel is realized by adjusting the variable parameters of the steering feel model according to different drivers’ preferences.