Electromagnetic actuator system using stepper motor with closed loop

Abstract

Using as an actuator a stepper motor operated in a position-sensed closed loop mode via an electronic commutator by position and anomaly corrected motion control signals provided by a programmable logic array and by a microprocessor, provides a precision power positioner. The correct enabling of the motor coils, based on position sensing of the motor phase, using electronic commutation for the stepper motor, transforms the problem of enabling coil selection to the programmable logic array, which by its logic provides a simplified operating control as a function of present armature position feedback, and by a microprocessor corrects for anomalies such as temperature rise, square-law, and phase increase as a function of position desired and present armature position feedback signals, and thus provides high positional accuracy, high speed and force (torque) control independent of the motor cardinal step positions. A standard three phase magnetic resistor sensor is used both to sense the motor phase and to feed back the motor position to the microprocessor for calculation of corrections; actual control of the stepper motor is communicated as a single amplitude modulated control signal.