Spacecraft Electromagnetic Docking Control Using Nonsingular Terminal Sliding Mode

Abstract

AbstractSpacecraft relative motion control using intersatellite electromagnetic interaction is a research hotspot in the field of spacecraft control. This paper presents an electromagnetic docking control scheme that combines a nonlinear sliding mode controller and a disturbance observer to solve the essential problems in spacecraft electromagnetic docking control, such as model uncertainties, unknown external disturbances, inherent high nonlinearity and strong coupling. First off, the far-field model is given and its modelling error is calculated and analyzed. Then, the translational dynamics model for electromagnetic docking is established. In the presence of the model uncertainties and the unknown external disturbances, a nonsingular terminal sliding mode-based translational controller driven by a disturbance observer is designed. The proposed control method is guaranteed to possess finite-time convergence and high-precision tracking. The whole closed-loop docking system is proven to be stable by a Lyapunov function. In the end of this paper, an electromagnetic docking simulation is conducted and the simulation results are presented to validate the effectiveness and merits of the proposed control scheme.KeywordsElectromagnetic dockingNonsingular terminal sliding mode controlFar-field modelDisturbance observer