Effects of sliding surface on the performances of sliding mode slip ratio controller for a HEV

Slip ratio control of a ground vehicle is an important concern for development of antilock braking system to avoid skidding when there is a transition of road surfaces. In the past, the slip ratio models of such vehicles were derived by several investigators. It is observed that the dynamics of the hybrid electric vehicle (REV) is nonlinear, time varying and uncertain due to tire-road dynamics being a nonlinear function of road adhesion coefficient and wheel slip. Sliding mode control (SMC) is a robust control paradigm which has been widely applied successfully to develop an antilock braking system of a REV. But the SMC performance is influenced by the choice of sliding surface. This is due to the discontinuous switching of control force arising in the vicinity of the sliding surface that produces chattering. This paper presents a detailed study on the effects of different sliding surfaces on the slip ratio control performances of a REV.