Disturbance Observer-based Nonlinear Feedback Control for Quadrotor Suspended Payload Transportation

This paper investigates the control challenges associated with quadrotor suspended payload transportation in the presence of unknown disturbances. The control system is systematically divided into outer-loop and inner-loop subsystems during the design phase. In the outer-loop, a disturbance observer is initially devised to estimate external disturbances. Subsequently, a nonlinear control scheme for quadrotor transportation is proposed, featuring an adaptive term within the controller to effectively estimate the upper bound of observed disturbances error. The inner-loop employs the Active Disturbance Rejection Control (ADRC) approach. Theoretical stability is rigorously established through Lyapunov analysis. The comparative simulation results demonstrate the exceptional performance of the proposed method, particularly in terms of mitigating payload swing and ensuring robustness.