Constrained Attitude Control for Flexible Spacecraft: Attitude Pointing Accuracy and Pointing Stability Improvement

This work deals with the complicated problem of constrained fixed-time attitude control for flexible spacecraft in view of actuator saturations and fault. The proposed controller is composed of two parts. The first part provides fast fixed-time convergence of system trajectories using a novel nonsingular terminal sliding mode control. The second part offers the desired performance specification, such as the rate of convergence, overshoot, and steady-state bounds for attitude/rotation velocity to improve attitude-pointing accuracy and pointing stability. The constrained control method ensures the desired performance in the transient/steady-state phases. It obtains a much simpler structure in comparison with other constrained controls. The simulations on a flexible spacecraft validate the efficacy of the planned scheme.