Patent ID: 6725965
Filing Date: 2004-04-27
Classification: B62D

Abstract:
An electric power steering system comprising:a torque sensor for outputting a signal corresponding to a value of a steering torque, said signal comprising a torque sensor output signal; a derivative means for outputting a signal obtained by differentiating the output signal of said torque sensor, said signal comprising a derivative means output signal; a driving means for electrically driving an assist apparatus which assists a steering force; and an electronic control unit (ECU) which performs the following steps to determine current flowing to said driving means; determining a first assist current in accordance with the torque sensor output signal and setting the first assist current to zero when the torque sensor output signal is smaller than a predetermined value; adding the derivative means output signal to the toque sensor output signal; and setting a gain of said derivative means to zero, or reducing the gain, when the torque sensor output signal is smaller than a predetermined value.