Optical tracking and stabilizing system with a gimbal mounted mirror for establishing a line of sight

Claim 1

An optical tracking and stabilizing system for establishing and maintaining a line of sight in response to a position command signal, comprising: a two-axis gimbal system controllable independently about each of its axes; a rigid block mounted to said gimbal system; a mirror mounted to said rigid block; gyroscope means mounted to said rigid block for providing a gyro rate signal about each of the axes of said gimbal system; means for providing a gimbal angle signal corresponding to the angular position of said rigid block about each of the axes of said gimbal system; means for receiving an input line of sight position command signal which defines a desired line of sight position to be attained by said mirror; and for each of said gimbal axes, means responsive to said gyro rate signal, said gimbal angle signal and said position command signal for generating an error signal to be applied to control said gimbal system, said error signal including first and second components, said first component passing through a high pass filter and corresponding to an inertial stable platform error signal based on said gyro rate signal, and said second component passing through a first low pass filter and corresponding to a position servo error signal based on said gimbal angle signal and said position command signal, wherein said high pass filter and said first low pass filter are mutually complementary.