Robust Control of a Quadrotor UAV with Cable-Suspended Load for Safe Transport and Delivery Applications

This work deals with the problem of controlling the transport of a load from one point to another through a cable connected to a quadrotor, and eliminating the oscillation generated by the suspended load. An ADRC controller is presented that asymptotically stabilises the desired position of the quadrotor while simultaneously limiting load oscillation and aligning it with the vertical position of the inertial reference frame. The proposed control scheme considers the dynamics generated by the suspended load to generate the control law. Unlike standard approaches in the scientific literature, feedback on the dynamics of the suspended load is not necessary since an extended state observer is designed to estimate it. The numerical simulation shows the effectiveness and stability of the proposed controller, thus contributing to the development of UAV-based sustainable mobility and safe transport applications such as purchased goods delivery, forest firefighting and aeromagnetic mapping.