Raytheon Company

Jerry Hershberg

Eric J Griffin

Michael L Brest

Amy M Yoshida

Thomas J Kostrzewa

Eric T Hughes

A drive mechanism having a bi-stable motor driving an actuator with a high starting torque, and a slower, regulated velocity as the actuator moves through its range of travel. This advantageously maintains high torque margins at low velocity, and lowers the kinetic energy of the bi-stable actuator at end of travel by limiting the terminal velocity and establishing a softer stop. A solenoid may be used in one embodiment. Actual bi-stable motor values are obtained immediately before the move to maintain accurate control of the motor, such as the resistance and inductance of the motor coil. For instance, the bi-stable motor may be driven into a stop, and the coil resistance may be calculated by sensing current associated with the calibration voltage. Inductance may be measured similarly by applying low level AC currents. Back-emf is sensed through the coil resistance, and an estimated motor rotation rate is sent to a feedback loop to maintain the desired rate.

Method for embedded feedback control for bi-stable actuators

A drive mechanism configured to drive a thermally isolated actuator between two positions. The drive mechanism includes a rotary actuated motor configured to rotatably drive a motor member, and a drive member coupled to the motor member and having a drive arm configured to responsively move from a first position to a second position upon rotation of the motor member. An actuator is responsive to movement of the drive arm moved from the first position to the second position. A drive circuit is configured to generate a pulse width modulated (PWM) drive signal configured to controllably drive the motor, the PWM drive signal having a first duty cycle configured to advance the drive arm from the first position, and having a second duty cycle different than the first duty cycle as the drive arm approaches the second position. The drive signal may be removed before the drive arm engages a hard stop. The drive mechanism may comprise at least one sensor configured to determine a position of the drive arm proximate the first position and proximate the second position. The actuator is thermally isolated from the drive arm in both the first position and the second position.

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Torrance, CA, United States of America

Jerry Hershberg