Improving stability and comfort of an in-wheel motor drive electric vehicle via active suspensions

This paper presents a method of a controller design to improve the handling and stability of an in-wheel motor drive electric vehicle using active suspensions with considerations of parameter uncertainties and control saturation. The construction of the mathematical model of vehicle suspensions combines active suspensions with vehicle lateral stability. Through the robust H infinity optimal control of active suspensions, the vehicle lateral stability has been improved and the vertical dynamic displacements of suspensions have been decreased. The uncertain parameters include the vehicle body mass, suspension spring stiffness and suspension damping coefficient. The control saturation considered results from the physical limitations of actuators. Active suspensions are designed with linear matrix inequalities (LMIs) feedback control method to attenuate the effect of the lateral acceleration on the roll angle and the suspension stroke. Simulation results show that the designed controller can improve vehicle handling and stability and has good robustness.