Antisaturation Adaptive Fixed-Time Sliding Mode Controller Design to Achieve Faster Convergence Rate and Its Application

This brief proposes an antisaturation adaptive fixed-time sliding mode controller for a class of second-order nonlinear systems with the saturation constraint. Based on the developed fixed-time stable system, a novel nonsingular fast fixed-time sliding mode surface is designed to circumvent the singularity and acquire a faster convergence rate. To avoid choosing inappropriate control gain, an adaptive mechanism is designed. Furthermore, an auxiliary compensation system is developed to solve the saturation constraint. It is rigorously proved that the system is practical fixed-time stable and the tracking error will fast converge to bounded regions within a fixed time. Finally, the obtained results are employed to realize the quadrotor attitude stabilization, and superior control performance can be illustrated via simulations and experiments.