| This thesis presents output feedback control algorithms for spacecraft formation flying (SFF). Although spacecraft are typically equipped with high precision position sensors, velocity sensors are usually omitted. Moreover, exact knowledge of SFF model is restricted to some extent due to uncertainties. In order to compensate for the lack of velocity measurement, replacement signal for velocity is generated by filtering the position signal. Three controllers are explored. Linear-Quadratic Regulator (LQR) strategy is used to facilitate control gain selection for linearized model. Two Lyapunov-based adaptive control laws, linear filter-based and nonlinear filter-based output feedback control, are explored for the nonlinear model. Simulations are conducted to verify the effectiveness of the proposed controllers. |
