Robust MPC-based Trajectory Tracking Control for Quadrotor UAV-slung Load System

This article investigates the problem of trajectory tracking control and avoiding collisions for a disturbed quadrotor unmanned aerial vehicle (UAV)-slung load system, specifically focusing on the scenario where the reference trajectory is unreachable. A tube-based model predictive controller (MPC) is presented, which enables simultaneous control of the quadrotor UAV's position and the payload's swing angles. Additionally, the introduced controller can also suppress the disturbances caused by the swing of the rope and the load. To ensure collision avoidance with both dynamic and static obstacles, MINVO basis is employed to calculate the minimum volume of the exterior polyhedral approximation of the obstacles' paths. The challenge of tracking an unreachable reference trajectory is effectively addressed through the integration of a trajectory planner and a trajectory tracking controller within a unified tube-based MPC problem. Detailed simulation results illustrate the efficacy of the introduced controller in a limited space with obstacles.