Abstract: An actuator control system includes a ballscrew type actuator for controlling the positioning of a valve device. A processing circuit is responsive to direction and drive signals for driving a synchronous stepper motor which is operatively coupled to the actuator. The processing circuit includes a switching device which applies a DC voltage to the motor windings to hold the valve position when it is not being driven. A limit sensing device provides a limit signal when the movable member of the actuator approaches a limit of travel. A limit control circuit responds to the limit signal to alternately reverse the direction signal applied to the processing circuit so long as that signal is representative of the direction in which the limit is being approached.

Abstract: An actuator control system includes a ballscrew type actuator for controlling the positioning of a valve device. A control circuit is responsive to pulsed drive signals for driving a synchronous stepper motor which is operatively coupled to the actuator. The control circuit includes a switching device which applies a DC voltage to the motor windings to hold the valve position when it is not being driven.