Realization of steer-by-wire system for electric vehicles using caster wheels and independent driving motors

Recently many works have been done on electric vehicle motion control. Most of them, however, still remain in the horizon of the conventional vehicle chassis structure, which is waste of ability. This paper presents a novel steer-by-wire system for electric vehicles using caster wheels and independent driving motors, which maximizes degrees of freedom in EV mobility and eventually distinguishes EVs from the ICEVs. A small-sized experimental vehicle is introduced and its basic dynamic characteristics are shown with actual experimental data. It is shown that the mobility of the vehicle can be improved by using caster wheels and independent driving motors at low speed, while it maintains stability at high speed. Feasibilities for future EV applications are shown with mathematical modeling and analyses, and control strategies are proposed in the paper.