A SMART WHEEL FOR ABS AND TRACTION CONTROL OF A 4WD ELECTRIC VEHICLE

The paper presents a braking and driving strategy based on the real time measurement of forces and moments at the wheels. The longitudinal forces at the wheels are optimally distributed between the front and rear axles on the basis the actual vertical loads distribution. For implementing on 4WD vehicles a standard ABS/traction control strategy (being the speed measurement of non-driven wheels not available), the vehicle longitudinal speed can be estimated via a vehicle model with relevant errors. The proposed strategy doesn’t rely on wheel slip information. The tire operating mode can be evaluated by measuring in real time the torque applied to the wheel and the wheel braking/traction force. The wheel spinning is detected and the actual friction coefficient estimated, as the tire vertical forces are measured in real time. In particular a six-components measuring wheel developed and patented at the Politecnico di Milano is applied. The proposed 4WD ABS and traction control strategy is verified by means of computer simulations.