Deadband error reduction in target sight stabilization

Abstract

A mirror or other target-sight element in a military vehicle is subject to oticeable vibration or dislocation relative to inertial space as the vehicle moves over rough terrain. To prevent such vibration or dislocation the mirror is driven by a torque motor that is controlled by a gyroscope that mechanically senses these mirror dislocations. The demodulated gyroscope output signal is amplified and applied to the torque motor, which thereby makes the correct repositionment of the mirror to keep the reflected image in a generally stable position in spite of terrain disturbances. The present invention contemplates a second gyroscope also responsive to vehicle pitch movements. The demodulated output signal of this second gyroscope is applied to a zero cross over detector, which produces a square wave output signal substantially in phase with the signal from the first gyroscope. When the first signal approaches its mean level the square wave signal has already crossed over the mean level; therefore the square wave signal produces an abrupt flip-over of the motor control signal that aids in reversing motor movement. The square wave signal minimizes deadband hysteresis effects of motor friction during motor reversal periods and thereby aids in stabilizing the mirror image.

Dependencies are inferred from the claim text.