Passivity evaluation of steering action with adjusting reaction torque to the driver

Steer-by-Wire (SBW) system has a mechanical feature that the conventional mechanical linkages between the steering wheel and the front wheel are removed, and is operated by electric actuators. SBW system suits for active steering control improving the maneuverability and stability of the vehicle. The bilateral control scheme has been applied to the SBW vehicle. From the view point of maneuverability, the reaction torque from the front wheel to the driver is important to achieve comfortable steering. Our objective is to design the advanced SBW system which adapts to the variations of the human and environment dynamics. In this paper, we evaluate dissipated energy at steering action of the SBW vehicle by using passive observer with adjusting the reaction torque to the driver. The SBW control system is implemented on the electric vehicle, and the steering passivity is evaluated in experiments.