PURPOSE: To improve a returning characteristic by carrying out judgement as to whether it is a steering holding state or not from a detection result of a steering system torque detection means and viscosity compensating value enumeration and renewing enumeration viscosity compensating value in accordance with a judgement result in the device for a vehicle.
CONSTITUTION: A detection signal of a torque sensor 11 is input to a viscosity compensating value enumeration part 52 of a motor speed feed back gain enumeration part 50 and a steering holding state judgement part 51 with an assist torque value indication function part 31 of an assist command part 30. Thereafter, the steering holding state judgement part 51 judges whether a steering handlewheel is in a steering holding state or not and outputs its judgement result to a viscosity compensating part renewal output part 53 (renewal output part hereinafter). In the meantime, the viscosity compensating value enumeration part 52 enumerates viscosity compensation (kv) in accordance with detection torque value and detection value of a car speed sensor 12, and it outputs it to the renewal output part 53. The renewal output part 53 renews the viscosity (kv) in accordance with judgement of the steering holding state judgement part 51, outputs the compensating value (kv) and adds it to output of the assist command part 30 and corrects it. By this corrected value, an electric current control part 35 controls an assist motor 6.
UEDA YOSHIHIRO
OGAWA YUKIO
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