Design and Robust Control of a Precise Torque Controllable Steering Module for Steer-by-Wire Systems

Abstract

Steer-by-wire(SBW) system has been introduced to reduce the number of parts in a vehicle by eliminating the mechanical link between the steering wheel and the tire. Even though intensive research has been conducted on the SBW system, performance of the actuator system that provides the desired steering feel still needs improvement.Therefore, this paper presents a compact size torque controllable steering wheel module for the SBW system, where the actuator that provides the steering feel to the driver is modularized with the gear mechanism and the spring. The steering torque sensing mechanism is compactly integrated by placing the spring inside the gear mechanism.Thanks to the advantage in the torque measurement and control ability by the spring mechanism, high gear-ratio transmission can be employed in the proposed module, which can also address the low inherent mechanical impedance problem that may cause fail-safety issue in the SBW system. To enhance the impedance rendering performance of the proposed module, internal model compensator which is composed of inertia and friction compensation is applied. The kinematics, statics, and dynamics of the proposed module are theoretically analyzed, and a model-based control algorithm is proposed based on this analysis result. Experiment confirmed the proposed algorithm. © 2022 IEEE