Robust Dynamic Compensator-Based Hierarchical Control for Quadrotor-Suspended-Payload System With Actuation Constraints

In the quadrotor-suspended-payload system, simultaneously achieving trajectory tracking and payload anti-swing control is essential but challenging. We reveal that the fast maneuver required by the anti-swing control may not be effectively executed by the classic quadrotor dual loop control framework, due to the inherent non-ideal inner loop actuation bandwidth in practice. To address this issue, we propose a novel hierarchical control framework incorporating the uncertainty and disturbance estimator (UDE)–based backstepping control. The proposed framework consists of three loops, where the outer loop tracking and anti-swing controller and the inner loop attitude controller are both designed in the conventional way, and more importantly, a newly proposed intermediate loop is induced between them. In the intermediate loop, the robust dynamic compensator is developed based on an experimentally verified actuator model to extend the quadrotor actuation bandwidth, such that the outer loop control bandwidth requirements are quantitatively satisfied. Furthermore, the system stability is proved by the Lyapunov method along with the system performance analysis based on the singular perturbation theorem. Finally, comparative simulation and experimental results are presented to demonstrate the feasibility and effectiveness of the proposed controller.