Control with distributed sensing on a large flexible spacecraft

The effective use of optical instruments in vibration control systems on spacecraft are described. These instruments sense relative deflection between targets fixed to a spacecraft and a detector. A linear quadratic Gaussian design process is presented and applied to a large flexible ground test facility, the Mini-Mast, for validation. For the design, nine optical targets are used, and their signals are emulated with noncontacting position transducers. Three torque wheel actuators are used for damping augmentation. Results are dramatic, indicating an improvement in damping from 3% to 30% of critical. The tests prove the effectiveness of the procedure in designing vibration damping systems. Additionally, a linear quadratic Gaussian design using a larger number of targets is presented. It is proposed that for large numbers of closely spaced targets one should implement the average value of the gains between adjacent targets to reduce the sensitivity of the Kalman filter to an individual target output