EELS: A Modular Snake-like Robot Featuring Active Skin Propulsion, Designed for Extreme Icy Terrains

This paper outlines the end-to-end electro-mechanicaldesign of EELS which is a novel modular snake-like robotwith active skin propulsion developed at NASA’s Jet PropulsionLaboratory. The goal of the development is to demonstratevertical mobility in glacier crevasses and moulins whichmotivates the unique design requirements and capabilities ofEELS. The robot is comprised of a proprioception head, tenidentical actuation modules and a power conditioning tail whichis connected to electronics ground support equipment (GSE)that provides power to the robot and houses the control computer.The design of each of these subsystems is motivatedand discussed in detail. The primary focus of this paper isthe actuation system. The actuation system is comprised ofshape actuators, which control the shape of the robot, and screwactuators, which control a multitude of propulsion screws alongthe surface of the robot. The actuation system design is outlinedand experimentally characterized. Detailed component levelanalysis is presented. Implementation challenges related to theunique architecture and their resolutions are outlined. Each ofthe actuation modules houses all the motor control electronics ina self-contained, integrated avionics compartment. Unlike thesnake robots previously introduced in the academic literature,EELS is the first large scale robot (weighing about 83Kg and4.4m in length) which has unparalleled ability to exert largeforces to the environment and support its own weight, thanksto its unique high torque dense shape actuators. The paperconcludes with detailed screw actuation analysis focusing onvertical mobility for EELS.