Path tracking Model Predictive Control of a Tilt-rotor UAV carrying a suspended load

This paper proposes a constrained Model Predictive Controller (MPC) to solve the path tracking problem of a Tilt-rotor UAV carrying a suspended load. Initially, a nonlinear model for the multi-body system is obtained via Euler-Lagrange formulation. Then, to design the constrained linear MPC, the equations of motion of the Tilt-rotor UAV with suspended load are linearized around the reference trajectory. Furthermore, to achieve null steady state error throughout the trajectory in presence of constant external disturbances and parametric uncertainties, the state vector is augmented with the integral action of some selected states. In addition, since the system is underactuated, the prediction model is also formulated in the incremental form to cope with disturbances affecting the system. Simulation results are carried out to corroborate the good performance of the proposed MPC when performing path tracking of the UAV with reduced load's swing.