Adaptive Second-Order Fast Nonsingular Terminal Sliding Mode Control for a Tilting Quadcopter

In this paper, we address the problem of modeling and control for a tilting quadcopter with unknown uncertainties. We propose a fully actuated tilting quadcopter, which suggests that the translational and rotational movements can be controlled independently. A complete dynamics is developed, where parametric uncertainties and external disturbances are considered. An adaptive second-order fast nonsingular terminal sliding mode control (ASOFNTSMC) is proposed toward the time derivative of control inputs, which can not only guarantee fast convergence both at a distance and at a close of the equilibrium, but also high precision with alleviating chattering effect. Moreover, the upper bound of uncertainties is expressed in a linearly parametric form, and its prior knowledge is not required. Finally, comparative simulation results are carried out to illustrate the effectiveness of the proposed scheme.