Nonlinear robust control of a quadrotor UAV for load transportation with swing improvement

This paper proposes a nonlinear robust control strategy to solve the load transportation problem by using a quadrotor UAV along a predefined trajectory. For the present study, the aim is to perform path tracking of the aircraft with load's swing-free, even in the presence of parametric uncertainties and exogenous disturbances. The system is modeled via Euler-Lagrange formulation considering both the dynamics of the quadrotor UAV and the suspended load. A nonlinear ℋ
_∞
controller for underactuated mechanical systems is proposed taking into account both actuated DOF due to input-coupling and unactuated ones. Furthermore, an additional control law obtained through the Lyapunov redesign technique is summed to the nonlinear ℋ
_∞
controller in order to reduce the load's swing. Simulation results are carried out to corroborate the proposed control strategy.