Adaptive fractional order non-singular terminal sliding mode anti-disturbance control for advanced layout carrier-based UAV

Advanced layout carrier-based UAV has grabbed increasing attention in aerospace field for its unique characteristics such as fewer casualties, lower labor costs and more capable of carrying out various tasks in shipping environment. However, the complex body structure of advanced layout UAV can bring about insufficiency in terms of stability, making it especially susceptible to changeable working circumstances. To overcome the object complexity and external disturbances mainly consisting of air turbulence that the UAV may come across, a composite adaptive fractional-order non-singular terminal sliding mode control strategy is proposed to achieve finite-time attitude tracking control and disturbance rejection. The distinctive features of the proposed strategy are embodied in active disturbance compensation, finitetime convergence, higher control accuracy and chattering suppression. The mathematical model of flying wing UAV is established first, then a fixed-time disturbance observer applying higher-order sliding mode is designed to obtain the estimation of unknown disturbance so that the carrier-based environment factors can be considered in the later control process. Next, an adaptive fractional-order non-singular terminal sliding mode controller is developed based on fractional order calculus and adaptive double power exponential reaching law to realize finite-time tracking control of advanced layout carrier UAV with great robustness against external disturbances due to the estimation from the proposed observer, and the stability analysis of closed-loop system is implemented by utilizing Lyapunov theory. Finally, a comparison study of the proposed strategy with other sliding mode control methods is presented by numerical simulation, to illustrate its feasibility and superiority. (c) 2023 Elsevier Masson SAS. All rights reserved.