Decentralized time-delay adaptive sliding mode control for attitude coordination of satellite formation under actuator misalignment

This paper develops an adaptive sliding mode attitude control system combined with time-delay control for the attitude coordination of satellite formation, especially when there exists the misalignment and magnitude error of active actuators. An adaptive update algorithm is presented to estimate the misalignment of actuators online, while the external disturbances together with random magnitude errors of an actuator are attenuated by the sliding mode controller. In addition, due to the introduction of the time-delay element, which just delays the last instantaneous control torque for a unit time, the complexity of controller design is greatly reduced. The stability of the closed-loop system is also proved based on the Lyapunov theory. Finally, the effectiveness of the corresponding controller is studied through numerical simulation. The results demonstrate that the external disturbance and random magnitude error can be attenuated by choosing appropriate control parameters, and the adaptive update algorithm can converge in a short time as well.