Motor-driven power steering system for a vehicle.

摘要

A motor-driven power steering system for a vehicle is disclosed in which the current supplied to a motor (13) is determined in dependence upon predetermined coefficients. The coefficients are stored in a memory (109c; 109d) and correspond to steering torque measured by a torque sensor (3). Appropriate coefficients correspond to a calculated change rate of the steering torque. Control of the motor current in this way enables fluctuations in the steering torque, due to time lags in operation of various component members of the steering system, to be substantially suppressed or reduced. Resultant vibrations of the steering system are prevented thereby providing a smooth and stable steering operation.