Fixed-Time Re-Entry Attitude Control Based On Nonsingular Terminal Sliding Mode

The fixed-time attitude tracking control scheme for reusable launch vehicles with uncertainties and external disturbances is investigated. A fixed-time convergent nonsingular terminal sliding mode controller is presented to guarantee that the attitude command can be tracked in a fixed-time. Lyapunov technique is used for deriving the proof of the fixed-time convergence of the closed system. The proposed control scheme is suitable for multivariable second-order systems and the settling time is predefined and bounded by a constant independent of initial conditions. Finally, numerical simulations are carried out to demonstrate the efficiency of the proposed method.