Adaptive saturated tracking control for spacecraft proximity operations via integral terminal sliding mode technique

Abstract This study presents a tracking control strategy for spacecraft proximity operations subjected to kinematic couplings, input saturation, modeling uncertainties, and external disturbances. First, a coupled six degrees of freedom dynamics is modeled to depict the relative motion between the pursuer and target spacecrafts. To address the input saturation problem, a dead‐zone operator‐based model is introduced. Subsequently, a finite‐time controller is proposed by exploiting the non‐singular integral terminal sliding mode method. By employing the adaptive technique, the proposed control strategy enjoys the feature that it can avoid requiring the prior knowledge of the lumped uncertainty's bounds. Using the Lyapunov theory, the designed controller is proved to guarantee that the translational and rotational tracking errors can converge to the origin within finite time. Finally, numerical simulations are performed to illustrate that the developed control scheme possesses a strong robustness, a fast convergence rate, input saturation elimination as well as chattering suppression.