Adaptive robust attitude tracking control of spacecraft

A nonlinear adaptive-robust scheme is presented to control a class of nonlinear systems. It effectively combines the design techniques of adaptive and robust control to improve performance by retaining the advantages of both techniques. It enhances transient performance and eliminates robustness problems compared to a parameter adaptive control. It also improves tracking performance by reducing modeling uncertainty and optimizes control effort by estimating bound uncertainty compared to a deterministic robust control. The controller is applied to a spacecraft making the body frame track a reference orientation, when there are parametric uncertainty, modeling errors, and external disturbances