Technical Note for "A Geodesic Approach for the Control of Tethered Quadrotors"
It addresses the control problem of tethered UAVs for applications requiring taut cables, but the approach is incremental, combining existing cascade control with geodesic path planning.
This paper proposes a cascade control scheme for a tethered quadrotor UAV to stabilize it at a desired position while keeping the cable taut, using a geodesic path approach. Asymptotic stability is proven via small gain arguments, and a reference governor enforces constraints.
This technical note focuses on the control of a quadrotor unmanned aerial vehicle (UAV) tethered to the ground. The control objective is to stabilize the UAV to the desired position while ensuring that the cable remains taut at all times. A cascade control scheme is proposed. The inner loop controls the attitude of the UAV. The outer loop gives the attitude reference to the inner loop, and is designed so that (i) the gravity force is compensated, (ii) the cable is taut at all times, and (iii) the trajectory of the UAV follows the geodesic path. To prove asymptotic stability, small gain arguments are used. The control scheme is augmented with a reference governor to enforce constraints.