Adaptive nonsingular fixed-time attitude stabilization for quadrotor
UAVs with multiple disturbances and uncertainties
Abstract
This article proposes an adaptive fixed-time attitude stabilization
control scheme for quadrotor UAVs in the presence of multiple
disturbances and uncertainties. Firstly, a novel nonsingular fixed-time
terminal sliding mode (NNFTSM) surface is proposed. The dynamic surface
guarantees non-singularity and fixed-time convergence so that the
setting time is independent of the initial states. Secondly, using the
proposed NNFTSM surface and adaptive technique, an adaptive nonsingular
fixed-time terminal sliding mode controller (ANFTSMC) is designed for
UAVs attitude stabilization. It yields exponential convergence of the
attitude tracking errors to zero without requiring a priori knowledge of
the upper bounds of the multiple disturbances and uncertainties. Then,
the stability of the closed-loop control system is validated by the
candidate Lyapunov function, and the upper bound of the convergence time
is given. Finally, the parameter design criteria and the convergence
time comparison are analyzed in detail. Comparative performances for
quadrotor UAV attitude stabilization are presented, and the
effectiveness and superiority of the proposed controller are illustrated
over the existing method.