Output Tracking Dynamic Feedback Linearization of a Multirotor Suspended Load System with Disturbance Robustness

This paper considers motion control of a slung load system (SLS) which consists of a multirotor unmanned aerial vehicle (UAV) carrying a slung load with a cable. This paper addresses the problem of tracking smooth payload position and UAV yaw trajectories. We design an output-tracking controller which can be used on a large practical region of state space and which has locally exponentially stable (ES) error dynamics. The method uses exact dynamic state-feedback linearization, and the controller expression is derived using the dynamic extension algorithm (DEA). Flatness relations are used to determine conditions for reference trajectories which avoid singularities. The proposed design achieves error dynamics which is ES in the presence of constant force and torque disturbance acting on the UAV. Finally, the proposed control law is compared to a geometric output-tracking design through numerical simulations, and the advantages of the proposed method are highlighted including its ease of tuning and disturbance robustness.