Electric Vehicle Lateral Dynamics Control based on Instantaneous Cornering Stiffness Estimation and an Efficient Allocation Scheme

Abstract

AbstractBeyond the establishment of a polution free mobility, electric vehicles show attractive features as far as vehicle motion control is concerned. In this work an electric vehicle equipped with four independent In-Wheel-Motors and active front and rear steering system is considered. The 6 actuators should be controlled in a way to guarantee safe, comfortable and low energy consumption drive. Generally, Linear Time Invariant (LTI) vehicle models are appropriate if the motion of the vehicle does not approach the physical limits of the tire force saturation and road conditions remain constant. Otherwise, they fail to predict the vehicle dynamics. On the other hand the control design approach based on LTI models is straightforward. The approach taken in this contribution is the following: use a robust sliding mode controller based on a slowly linear time varying model, together with an efficient estimation scheme for the instantaneous cornering stiffness in order to prevent the vehice to reach lateral tire force saturation by restricting the possible actuator outputs in a control allocation scheme. Computer simulation runs with the professional vehicle dynamics environment CarSim show good performance of the control scheme. Further work will be the validation with real vehicle experiments and modelling of consumed energy for consideration of energy efficency in the control scheme.