Trigonometric-Type Sliding Mode Attitude Control for Rigid Spacecraft with Arbitrary Convergence Time

In this paper, the problem of attitude tracking control with arbitrary convergence time is addressed for rigid spacecraft subjected to external disturbances. A novel time-varying sliding mode function is proposed, which enables the system states to converge at an arbitrarily specified time once they reach the sliding surface. Building on this function, an attitude tracking controller is designed to guarantee that the closed-loop system states reach the sliding surface within a predefined time, even in the presence of external disturbances. Numerical simulations are provided to demonstrate the arbitrary convergence time properties of the closed-loop system.