Robust control of aerial cable-suspended payload transportation via fully actuated system approach

Unmanned aerial vehicles with cable-suspended payloads suffer from underactuation, strong coupling, and disturbances. These factors often cause payload swing and degrade tracking performance. This paper proposes a robust control method based on the fully actuated system (FAS) framework. The system dynamics are reformulated into a reduced-order FAS form with virtual constraints. The remaining states are arranged into a cascade structure for ensuring stability. On this basis, FAS controllers are designed for both outer-loop dynamics (UAV position and payload swing) and inner-loop attitude dynamics. Disturbance observers are introduced to handle external disturbances. Stability is proved through cascade analysis. Simulations and experiments confirm that the proposed controllers achieve robust waypoint tracking with improved swing suppression.