Terminal Sliding Mode Autopilot Design for a High Maneuver UAV

In order to investigate the nonlinear coupling control characteristics of bank-to-turn (BTT) Unmanned aerial vehicle (UAV), an adaptive terminal sliding surface with overload tracking error and the integral of it is designed to ensure the state of the system on the sliding surface throughout the control process based on the simplified nonlinear coupling dynamic model. Also, the system chattering is eliminated using the hyperbolic tangent switch function replaces the sign function. Then, sliding mode variable structure control law is designed according to the asymptotical stability of sliding mode motion and its dynamic quality to meet the requirements The Simulink simulations of the nominal and perturbed systems using the control algorithm are carried out. The results show that the tracking error of the nominal system and the perturbation system is approximately zero under the longitudinal and lateral overload commands, which indicates that the sliding mode control scheme is one of the effective methods to give the solution of the nonlinear coupling control of the BTT UAV.