Attitude control of combined spacecraft with fuzzy neural network disturbance observer

A finite-time control strategy based on a fuzzy neural network disturbance observer (FNNDO) and nonsingular terminal sliding mode (NTSM) is proposed for the attitude control system of a combined spacecraft in the presence of non-cooperative targets with competitive torque output. First, a mathematical model of the combined spacecraft attitude is established with the service spacecraft as the reference. Then, the external disturbances and competitive torque output from non-cooperative targets are treated as generalized disturbances, and FNNDO is employed for tracking and compensation. Subsequently, a NTSM controller is designed to achieve finite-time attitude takeover control of non-cooperative targets. The stability of the disturbance observer and controller is proven using Lyapunov stability theory. Simulation results demonstrate that this control strategy effectively handles the competitive actions of non-cooperative targets while rapidly stabilizing the combined spacecraft's attitude at the desired values.