Adaptive backstepping fast terminal sliding mode controller design for ducted fan engine of thrust-vectored aircraft

In this article, a combination of backstepping control and fast terminal sliding mode control is considered for controlling a ducted fan engine of thrust-vectored aircraft subject to parameter uncertainties and external disturbances. To increase the speed of convergence of the system states to the equilibrium points or to decay state errors to zero, the fast terminal sliding mode controller is used. For the first design, to compensate for uncertainties and also incoming disturbances to the system, a new backstepping fast terminal sliding mode control (BFTSMC) is derived. At the second design, to estimate the upper bound value of the lumped uncertainty in the BFTSMC, an adaptive rule is proposed, and an adaptive backstepping fast terminal sliding mode controller (ABFTSMC) is obtained. The asymptotic global stability of the closed-loop system is proved by Lyapunov stability theorem. Various scenarios are considered; then, the designed controllers are compared with traditional sliding mode controller (SMC) and adaptive SMC (ASMC) in the presence of external disturbances. Simulation results show that the proposed controllers can have a faster transient response and higher robustness against different types of disturbances in comparison with SMC and ASMC. Some advantages of the proposed controllers are simplicity in design and implementation, improving closed-loop system stability and better tracking.