Energy-Efficient Collaborative Transport of Tether-Suspended Payloads via Rotating Equilibrium

TL;DR

This paper introduces a rotating equilibrium method for tethered aerial payload transport, reducing energy consumption by enabling purely vertical thrust and expanding feasible configurations.

Contribution

It proposes a novel rotating equilibrium approach that minimizes energy use in tethered payload transport by maintaining steady circular motion.

Findings

Rotating equilibrium reduces power consumption by up to 20%.

The method allows for wider tether configurations without efficiency loss.

Steady circular motion enables purely vertical thrust in aerial payload transport.

Abstract

Collaborative aerial transportation of tethered payloads is fundamentally limited by space, power, and weight constraints. Conventional approaches rely on static equilibrium conditions, where each vehicle tilts to generate the forces that ensure they maintain a formation geometry that avoids aerodynamic interactions and collision. This horizontal thrust component represents a significant energy penalty compared to the ideal case in which each vehicle produces purely vertical thrust to lift the payload. Operating in tighter tether configurations can minimize this effect, but at the cost of either having to fly the vehicles in closer proximity, which risks collision, or significantly increasing the length of the tether, which increases complexity and reduces potential use-cases. We propose operating the tether-suspended flying system at a rotating equilibrium. By maintaining steady circular motion, centrifugal forces provide the necessary horizontal tether tension, allowing each quadrotor to generate purely vertical thrust and thus reducing the total force (and power) required compared to an equilibrium where the thrusts are not vertical. It also allows for a wider range of tether configurations to be used without sacrificing efficiency. Results demonstrate that rotating equilibria can reduce power consumption relative to static lifting by up to 20%, making collaborative aerial solutions more practically relevant.