Driving Force Distribution and Control for EV With Four In-Wheel Motors: A Case Study of Acceleration on Split-Friction Surfaces

Motion stabilization for electric vehicles with four in-wheel motors has been extensively studied in recent years. While most of the previous works have tended to focus on the development of optimization algorithms for driving force distribution, this paper considers a global-local control scheme: the global controller coordinates wheel and vehicle motions to generate reference driving forces and the local controller further controls the generated force commands. Specifically, two approaches with different global control concepts are proposed. The first approach considers the redesign of weighting factors for a conventional driving force optimization algorithm, and based on the first method, the second approach formulates the objective function and equality constraints in a two degree-of-freedom control framework. As an example, vehicle start off on an instantaneous split-friction road is employed to verify the proposed methods in both simulations and experiments.