Disturbance and parameter estimation algorithms for attitude control model of the satellite maneuvers

The design of robust tracking control for a nonlinear MIMO system having modeling uncertainty and unknown disturbance is one of the most complicated control problems. In this paper two new algorithms for tracking control are presented which guarantee the satellite attitude during small maneuvers having desired attitude angle. The amplitude of the control signal and consumed energy is less than the related value concerning the sliding mode with perturbation estimation, which are usually applied for large maneuvers. The first method by means of decoupling the equations and the modeling uncertainty in the form of disturbance introduces the direct relationship between the control system and the desired conditions. This method also enables the possibility of designing controller with minimum calculation in the classical form. In the second method by system identification and external disturbance an adaptive controller has been designed in which the shape of the control signal is smoother than that of the first method. The amplitude of the control signal has been reduced which is more suitable than the first method for maneuvers with large angles. The test results have been illustrated in the last section of this paper