Abstract
In this paper, we propose a novel mechanism for attaching payloads to pole-like structures, titled GRASPER (GRavity ASsisted Payload EntangleR). Inspired by the tangling-based weapon 'bolas', the 'pendulum catch' experiment and driven by SWaP (size, weight and power) constraints imposed on aerial platforms, we developed GRASPER as an alternative to arm-based grippers for load transportation and attachment tasks specific to pole-like structures. It works with two-bodies; a counterweight and a payload that are released onto a pole at height. Being a passive attachment system, it is lightweight, simple to use, surprisingly robust and functions remotely at a distance; a plus for rotorcraft endurance and safety. To study GRASPER, we first define a model accounting for the influence of gravity, rotational dynamics and the Capstan effect on a two-body system released from rest. The time-evolution of the system is simulated numerically, then compared against real-world experiments across variables such as mass, string length and counterweight types, with design implications for GRASPER derived thereafter. Finally, we demonstrate its feasibility of implementation on a typical quadrotor for aerial payload deployment applications.