Novel Sensing Scheme For A Six Degree-Of-Freedom Precision Pointing Magnetic Actuator

A novel six degree-of-freedom (DOF) prototype gimbal system is constructed to demonstrate the new gimbals for space laser communication applications. The precision pointing magnetic actuator is essentially an open loop unstable system, feedback control is therefore indispensable. To realize ultra-fine pointing accuracy over relatively large gimbal angles, the sensing scheme is critical for the actuator performance. To provide high resolution and contact free feedback for several functions simultaneously at a minimal cost, a novel sensing strategy that uses a tape encoder and hall effect probe arrangement is proposed. In this paper, the prototype gimbal system is introduced and the requirements for the feedback devices are analyzed first. The sensing scheme is presented and its decoding logic is explained. Issues involved in this scheme are discussed. Finally, the proposed sensing scheme is validated by experimental results.