Fixed-Time Fractional-Order Sliding Mode Control for UAVs under External Disturbances

Abstract

The present paper investigates a fixed-time tracking control with fractional-order dynamics for a quadrotor subjected to external disturbances. After giving the formulation problem of a quadrotor system with six subsystems like a second-order system, a fractional-order sliding manifold is then designed to achieve a fixed-time convergence of the state variables. In order to cope with the upper bound of the disturbances, a switching fixed-time controller is added to the equivalent control law. Based on the switching law, fixed-time stability is ensured. All analysis and stability are proved using the Lyapunov approach. Finally, the higher performance of the proposed controller fixed-time fractional-order sliding mode control (FTFOSMC) is successfully compared to the two existing techniques through numerical simulations.

Predefined-Time Fractional-Order Tracking Control for UAVs with Perturbation

“…Predefined-time stability can keep the nonlinear system stable within a predetermined upper limited convergence time, which is directly associated with an adjustable variable [20,21]. Although less conservative than the fixed-time control approaches now in use, the system's upper limited convergence time under predefined-time control methods is still adequate [22,23]. The fixed-time control method and the finite-time control method have drawbacks, which can be more effectively addressed by the predefined-time control strategy.…”