좌우독립형 Steer-by-Wire 시스템을 이용한 능동조향 제어알고리즘 개발

Abstract

The Steer-by-Wire system is a part of X-by-Wire system. It has no mechanical part between steering wheel system and front wheel system, which is connected by wire. Steering wheel system is operated by a motor which generates steering reactive torque. It uses front wheel motor to transfer information of the road to the driver to improve the steering feel. Front wheel system is Tie-rod actuating type which has two independent actuating and it uses position feedback control to accurate steering and to improve maneuverability and stability. In this study, the steering wheel motor and the front wheel motor are modeled using Bond graph method and controlled. To improve steering feel and to transfer road information to the driver, the torque map for determining the steering reactive torque and the filtered front wheel motor current transferring road information are used. Moreover, the torque map can be easily adjusted by changing control parameters. On-center handling characteristic treats steering-torque gradient and steering-wheel returnability as important control factors. The control factors that affect on-center handling performance are analyzed. To improve vehicle stability variable gear ratio and active steering control algorithm with stability factor (S(V)) are proposed. In this study, an experiment for steering wheel system is performed through HILS and a simulation for front wheel system is performed through CarSim.