Design a finite-time chattering free attitude controller for rigid spacecraft’s without angular velocity measurement using interval type-II fuzzy logic nonsingular terminal sliding mode and nonlinear extended state observer

This paper proposes an intelligent output feedback control method for rigid satellites considering dynamic uncertainties and external disturbances. The dynamics of a rigid satellite are first represented using the modified Rodrigues parameter (MRP) explanation, and then transformed into Lagrangian form in order to build the state-space representation of the dynamics. Because of cost or technical restrictions, angular velocity data are not always accessible for practical application.So angular velocity is considered to be unmeasurable. In order to avoid increasing mathematical calculations and designing separate observers to estimate external disturbances and system states, a non-linear extended state observer has been used to simultaneously estimate disturbances and system states. In order to estimate the system's dynamics in light of the parametric uncertainties, the interval type-۲ fuzzy logic approach has been used. The main part of the proposed controller is also composed of the non-singular terminal sliding mode method, which guarantees finite-time stability and elimination of chattering phenomenon. The simulation results of the proposed method have been presented and compared with the results of the methods available in the literature, which shows the efficiency of the method proposed in this paper and the improvement of the results of the methods presented in previous related researches.