Vertical vibration control of an in-wheel motor-driven electric vehicle using an in-wheel active vibration system

The objective of this study is to present a novel in-wheel (IW) active vibration system for an IW motor (IWM)-driven electric vehicle to overcome the negative effects of vertical vibration due to road roughness and the impact of rotary inertial forces from the IWM. First, the reason for the poor ride comfort of the general electric wheel structure is examined by theoretical derivation. Second, a 6 degree-of-freedom (DOF) vehicle model is established and the corresponding cost function based on 10 ride comfort indexes is proposed. Third, a fuzzy optimal sliding mode (FOSM) control method is presented and the IW active vibration system is designed by applying this proposed control theory. Then, normalization and analytic hierarchy process (AHP) methodologies are adopted to select reasonable weighted coefficients of performance indexes. Finally, the advantages of the electric vehicle with the IW active vibration system are illustrated by MATLAB/Simulink. Analysis results demonstrate the feasibility and effectiveness of the proposed method.