Robust control design for spacecraft attitude systems with unknown dead zone

In this paper, we consider the challenge of controlling inherently complicated nonlinear systems accompanied by input´s hard nonlinearities characterized by unknown parameters. This challenge is addressed in this paper by considering the problem of controlling the attitude of a spacecraft when unknown dead zones exist at the actuators. The spacecraft´s dynamics is described by the exact form of Euler´s equations of motion, allowing for the case of large angle of rotations to be considered. We propose a control scheme that ensures the spacecraft´s attitude to track time-varying maneuvers with an exponential tracking error convergence and robustness to actuator dead zones uncertainties. Numerical simulation results along with the theoretical proof show that the proposed control scheme can successfully stabilize the attitude of the spacecraft and achieve the desired tracking performance.