ELECTRIC POWER STEERING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an electric power steering device in which an assist characteristic having hysteresis is applied at the time of going-steering and returning steering, and steering feeling at a neighborhood to a central point of a steering angle is also good. SOLUTION: The device carries out an assist of steering by transmitting driving force of an electric motor M to a steering mechanism 3. A basic assist characteristic is memorized in an assist characteristic memory part 22. An assist torque target value setting part 21 determines an assist torque target value according to the basic assist characteristic at the time of going-steering and determines the assist torque target value by multiplying a hysteresis coefficient on the basic assist characteristic at the time of returning steering. A hysteresis coefficient target value setting part 23 determines a hysteresis coefficient target value corresponding to a steering torque. The assist characteristics approximately become equal at the time of going-steering and returning steering at a neighborhood to an end of a non-sensitive band. COPYRIGHT: (C)2004,JPO