MOTOR-DRIVEN POWER STEERING DEVICE

摘要

PURPOSE:To improve a steering feel by increasing the returning speed of a steering wheel while ameliorating instability when the steering wheel is released and returned at high vehicle speeds. CONSTITUTION:A signal indicative of detected steering angle acceleration is fed to a fuzzy algorithm filter 52 which advances the phase of signals indicative or detected steering angle acceleration in a desired frequency band (1 to less than 20Hz which poses problems in a motor-driven power steering unit) by utilizing the nonlinearity of fuzzy algorithm and which has a noise eliminating function, and an inertia control signal is obtained based on a signal indicative of steering angle acceleration, extracted through the filter 52. The inertia control signal is positive fed back to an assist command value for controlling a steering assist motor. A variation means 100 is used to compensate for gain losses in a frequency band of less than the above frequency band (less than 1Hz).