Fuzzy sliding mode control of traction control system for electric scooter

A traction control system (TCS) using fuzzy sliding mode control (FSMC) is proposed for the electric scooter with direct driven wheel motor in this paper. First, road friction coefficient is estimated using normal force observer and traction force observer. A road condition observer is then employed to estimate the gradient of road friction coefficient with respect to the tire slip ratio. An innovative rule is proposed to determine the reference slip ratio based on the estimated gradient. According to the error and error change of the slip ratio, the FSMC adjusts the driver's torque demand to obtain the reference torque command for the wheel motor. Preliminary simulation results show that the proposed TCS can detect the road friction change and control the motor torque to maintain the slip ratio in the stable region, thus enhance the traction performance for low friction surface.