Terminal sliding mode control technique for flight control design of quadrotor

A terminal sliding mode control (TSMC) based algorithm for altitude and attitude tracking of a Quad-rotor type Unmanned Aerial Vehicle (UAV) is proposed. TSMC is a novel class of sliding mode control giving rise to a finite-time convergence of reduced order dynamics, delivering fast response, high precision, and strong robustness. This is achieved by choosing a sliding surface of nonlinear dynamics unlike linear dynamics for conventional sliding mode control. TSMC shows an improved performance over conventional SMC in altitude and attitude control in presence of disturbances. The design procedures for both control i.e. SMC and TSMC are described thoroughly and convergence is proved by using Lyapunov Stability. Effectiveness of the control method is shown by numerical simulations of Quadrotor in various situations and compared with conventional SMC. The results show that the TSMC presents lower transient time to reach the final value because of its finite-time convergence property.