Heading for the Abyss: Control Strategies for Exploiting Swinging of a Descending Tethered Aerial Robot

The use of aerial vehicles for exploration and data collection has the potential to significantly aid environmental monitoring in environments which are dangerous and hard to navigate. However, within these environments navigation can often be restricted by overhangs which are challenging to navigate, particularly so with the high payloads required for environmental monitoring. We propose utilizing a tethered bicopter with vertically mounted propellers. This pendulum like system can exploit the tether, not only as a means of powering and recovering the robot, but also to assist its motion, i.e. by swinging to increase the workspace of the robot. Using PD-based control, we demonstrate how the system can be stabilized and bang-bang control to excite the system to achieve large amplitude swinging. By combining these controllers, we show how the system can be used to navigate in a glacial-inspired scenario where there are overhangs and obstacles through which the robot must navigate.