Adaptive Fixed-Time Attitude Tracking Control in Reentry Phase for Reusable Launch Vehicle

An adaptive fixed-time control method is proposed for reusable launch vehicles (RLV) subject to full state constraints, input saturation, dynamic coupling, parameter uncertainty and disturbance. By using the back-stepping control technique, an integrated adaptive fixed-time control law is designed, which combines the tan barrier Lyapunov function (BLF) to deal with the full-state constraints. At the same time, parameter uncertainty, unknown dynamic coupling, and perturbations are effectively attenuated by using adaptive estimation techniques and the designed saturation compensator effectively reduces the adverse effects caused by input saturation. Finally, six-degree-of-freedom simulation proves the advantages and effectiveness of the designed adaptive fixed-time control method.