Attitude Control of Spacecraft under Restricted Network Using Robust Event Triggered Optimized Strategy

The controller design for a bandwidth constraint wireless control system requires a dedicated aperiodic control update strategy. In this paper, an event-triggered (ET) adaptive sliding mode control (SMC) is proposed for the attitude stabilization of a spacecraft, which is subjected to the inertial matrix ambiguity and surrounding disturbance with limited resources of communication. The proposed event-triggering rule is generic because it is developed with the use of Lyapunov theory. Thus, it can easily be extended to other dynamical systems as well. The adaptation law designs the switching gain of the SMC. Hence, a priori upper bound knowledge of disturbance is avoided. The nominal controller gains are optimized using a metaheuristic technique called the sine cosine algorithm. Moreover, the sliding manifold also resolves the inherent issue of unwinding in the quaternion based orientation. The theoretical result guarantees the uniformly ultimately bounded stability of the system and ensures the convergence of state variables to the nearest stable point. Furthermore, it is also proved that the proposed scheme is free from the Zeno behavior. The comparative analysis with the existing ET SMC scheme, through numerical simulation, illustrates the efficacy of the proposed approach in settling time, convergence bound, energy consumption, number of transmissions via a communication channel, and successfully eliminating unwinding.