OPTIMAL LINEAR-QUADRATIC GAUSSIAN DIGITAL-CONTROL OF AN ORBITING TETHERED ANTENNA REFLECTOR SYSTEM

Analysis and design of linear quadratic Gaussian (LQG) optimal digital controllers and estimators are presented for a flexible orbiting teth ered shell system. Emphasis is placed on mathematical models of the dy namics, influence of the number of actuators and their locations, meth ods of measurement of the state variables, and design of LQG optimal d igital controllers and observers. Attitude and shape control is accomp lished using point actuators and tether tension. A new practical metho d is presented to measure the tether transverse motion. Actuator and s ensor placements are obtained by means of the concept of the degree of controllability and observability, as well as related simulations. Th e analysis and design of the optimal LOG digital control system for th e tethered shell has been validated by simulation. After maximizing th e degree of controllability and observability, the best combination of the controller and observer pole locations is found by carefully sele cting the weighting matrices. Typical figures show satisfactory transi ent response under LQG control laws.