Practical prescribed time attitude stabilization of combined spacecraft with measurement uncertainties

This paper investigates a novel practical prescribed time attitude control method for post-capture combined spacecraft with the prescribed performance for attitude and angular velocity in the presence of external disturbances, unknown inertia, measurement uncertainties, and input saturation. Control design faces a significant challenge in ensuring the control performance of the attitude and angular velocity at the same time. To solve this problem, a novel practical prescribed time attitude controller is proposed. First, a performance constraint function is used to achieve the desired performance for attitude and angular velocity. Second, a nonlinear transformed function is employed to cope with full-state constraints. Then, a prescribed time attitude controller is designed based on the dynamic surface control technique, where an auxiliary system is used to deal with input saturation. Analysis based on the Lyapunov stability theory proves that the closed-loop system is stable, and both the attitude and angular velocity converge to a specified region around the desired values within a prescribed time. Compared with the previous works, the proposed control method can simultaneously ensure the desired performance for attitude and angular velocity and has a smaller overshoot and a faster convergence rate. Numerical simulations and comparison results with other controllers validate the effectiveness and superiority of the proposed control approach.