Pointing Control System for a High Precision Flight Telescope

摘要

This project was funded to retrofit a gimballed telescope (which was built over ten years ago) to incorporate the latest advances in servo technology and thereby achieve an order-of-magnitude improvement in pointing accuracy and line-of-sight stability. There was little documentation on the existing control system. However, inputioutput characterization determined that it was lightly damped, and limited in disturbance rejection capability. Furthermore, the servo was velocity limited to 2.50/sec, which severely restricted its step response for large re-targeting maneuvers. The telescope was retrofitted with precision resolvers and new (higher torque) motors. This paper will describe in considerable detail, the new servo system including each sub-system, namely the gimbal (including the motor, and bearing friction), Inertial Angle Sensors (IAS), resolvers (including the resolver-to-digital converters), Inertial Measurement Unit (IMU), feedback compensator, feedback sensor blending compensator, motor power amplifiers, and IAS notch filters.