| The control aspects of pointing, acquisition, and tracking a laser beam between two satellites separated by thousands of mile distances, crucial for successful laser-based space communication, are being investigated. Experimental analysis, characterization, mathematical modeling, and development of simulation models of existing beam steering devices has been conducted. Several factors adversely affecting performance of beam steering systems, such as limited bandwidth, dynamic cross-coupling, and transient vibrations were detected. The feedforward compensation approach resulting in a significant reduction of the disturbing effects of satellite jitter on laser-based space communication has been developed and validated. Various aspects of the model reference adaptive control approach to performance modification of laser positioning systems are investigated. A simplified model-following procedure, resulting in performance enhancement of laser positioning systems and particular beam steering devices was developed and tested. An analytical model-following controller design technique intended for multivariable systems described by transfer matrices was formulated. A model reference decoupling control technique utilizing an adaptive predictor and intended for digital implementation was developed and tested. The obtained results were implemented in hardware and subjected to laboratory testing using a laser communication testbed. A unique procedure for laser power control, relating the immediate transmitted power to the estimated positioning accuracy has been formulated. |
