Adaptive Barrier Fast Terminal Sliding Mode Actuator Fault Tolerant Control Approach for Quadrotor UAVs

Abstract

This paper proposes an adaptive barrier fast terminal sliding mode control (ABFTSMC) approach for quadrotor unmanned aerial vehicles (UAV). Its main objectives are to mitigate the external disturbances, parametric uncertainties, and actuator faults. An adaptive barrier function is considered in the design to ensure the finite-time convergence of the output variables to a predefined locality of zero, independent of the disturbance bounds. A fast terminal sliding mode control (FTSMC) approach is designed to speed up the convergence rate in both reaching and sliding phases. The design considers hyperbolic tangent functions in the adaptive control law to drastically reduce the chattering effect, typically associated with the standard SMC. The performance of the proposed approach was assessed using a quadrotor UAV subject to external disturbances and sudden actuator faults. The obtained results show that the trajectory and the sliding surface converge to the origin in a finite time, without being affected by the high disturbance and actuator faults. In this method, due to the substitution of the discontinuous function by the hyperbolic tangent function, the chattering effect has also been highly reduced.

Finite‐time robust performance improvement for non‐linear systems in the presence of input non‐linearity and external disturbance

“…Theorem 1. Consider the uncertain nonlinear system (1). If the disturbance observer is designed as Equation ( 6), the disturbance estimation error of the disturbance observer is converged to zero in the finite time.…”

“…□ Theorem 3. Consider the uncertain non-linear system (1) and the global non-linear sliding surface (17). Let full state information be available and the disturbance observer be designed as Equations ( 4)- (6).…”

“…In dynamical systems, actuators are usually subjected to hard non-linearities such as dead-zone (or dead-band), backlash, saturation, hysteresis, quantization, and others. Such a character would have significant effects on the system's stability and performance [1][2][3]. Nowadays, several control strategies have would be straightaway tricks for the hard non-linearity in the linear time-invariant (LTI) systems [9].…”

“…In dynamical systems, actuators are usually subjected to hard non‐linearities such as dead‐zone (or dead‐band), backlash, saturation, hysteresis, quantization, and others. Such a character would have significant effects on the system's stability and performance [1–3]. Nowadays, several control strategies have been developed to handle input nonlinearity [4], with methods such as the anti‐windup scheme [5], composite nonlinear feedback [6], and constructing the augmented system [7] being the most important.…”

Constrained Nonsingular Terminal Sliding Mode Attitude Control for Spacecraft: A Funnel Control Approach

“…Therefore, an exact estimate of the settling time cannot be acquired. In comparison with the control schemes derived from this concept [14][15][16][17][18][19], control laws using the fixed-time stability lead to finite-time convergence of the system states regardless of their initial value [20][21][22]. The significant feature which distinguishes fixed-time control from its finite-time counterpart is that the settling time for the closed-loop system is specified based on the controller gains.…”