  This paper proposes and benchmarks two tether-based motion primitives for
tethered UAVs to execute autonomous flight with proprioception only. Tethered
UAVs have been studied mainly due to power and safety considerations. Tether is
either not included in the UAV motion (treated same as free-flying UAV) or only
in terms of station-keeping and high-speed steady flight. However, feedback
from and control over the tether configuration could be utilized as a set of
navigational tools for autonomous flight, especially in GPS-denied environments
and without vision-based exteroception. In this work, two tether-based motion
primitives are proposed, which can enable autonomous flight of a tethered UAV.
The proposed motion primitives are implemented on a physical tethered UAV for
autonomous path execution with motion capture ground truth. The navigational
performance is quantified and compared. The proposed motion primitives make
tethered UAV a mobile and safe autonomous robot platform. The benchmarking
results suggest appropriate usage of the two motion primitives for tethered
UAVs with different path plans.
