CONTROL TO AIMED OPENING DEGREE OF CONTROL VALVE OF AUTOMOBILE

PURPOSE:To avoid resonance by monitoring the lapse time from the switching of the output port value immediately before the interruption, in each interruption, and suspending the switching of the output port value when the accordance with the resonance time of the step motor is judged. CONSTITUTION:Judging traction control from the slip of a driving wheel, a microcomputer 104 executes interruption on the basis of the throttle opening degree detected by a detector 46 and calculates the aimed opening degree for each interruption, and a pulse train is outputted in succession into each phase coil 100-103 through the transistors 113-116 for drive, and a throttle valve is driven in the closing direction by a step motor. In the case, the lapse time from the switching to the different output port value immediately before the interruption is monitored for each interruption, and if the lapse time accords with the resonance time of the step motor, switching of the output port value is suspended. Therefore, resonance is avoided, and slip-off, etc., of the step motor can be prevented.