Trajectory tracking of free-flying space manipulators using time-delay logarithmic sliding mode control

Abstract In space operations, the requirements for control precision, stability, and robustness of free-flying space manipulators are critical for mission success. However, due to unknown system dynamics and external disturbances, control performance may degrade. To address these challenges, this paper proposes a new sliding mode control method to achieve fast and accurate tracking for space manipulators, even in the presence of lumped disturbances. In this method, the sliding surface design incorporates the value of the sliding surface at the previous sampling time, and the resulting surface is referred to as the time-delay logarithmic sliding surface. This design enables the proposed time-delay logarithmic sliding mode control method to improve the robustness of the closed-loop systems without the need for any approximation or compensation mechanisms, and improve tracking accuracy without introducing complex structures. Numerical simulations are conducted to demonstrate the effectiveness of the proposed approach in improving tracking performance for free-flying space manipulators.