Optimal control of an On-Demand All-Wheel Drive system (ODAWD) for vehicle traction enhancement

This paper presents an optimal algorithm to enhance the performance of an On-Demand All-Wheel Drive (ODAWD) vehicle by traction improvement through regulation of wheel slip. A 'Minimum Fuel Problem' is developed with a cost function minimising the slip error and the control action defined as the ratio of the total torque transmitted to the non-driven wheels (rear wheels). A simplified vehicle model (bicycle model) is used to develop the proposed controller to optimally reduce the wheel slip error by engaging and dynamically controlling a hydraulic clutch. The controller performance was validated on a realtime Hardware-in-Loop (HIL) bench.