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

This paper describes the end-to-end electro-mechanical design of EELS which is a novel modular snake-like robot with active skin propulsion developed at NASA’s Jet Propulsion Laboratory. The goal of the development is to demonstrate vertical mobility in glacier crevasses and moulins which motivates the unique design requirements and capabilities of EELS. The robot is comprised of a proprioception head, ten identical actuation modules and a power conditioning tail, which is 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 motivated and discussed in detail. The primary focus of this paper is the actuation system. The actuation system is comprised of shape actuators, which control the shape of the robot, and screw actuators, which control a multitude of propulsion screws along the surface of the robot. The actuation system design is outlined and experimentally characterized. Detailed component level analysis is presented. Implementation challenges related to the unique architecture and their resolutions are outlined. Each of the actuation modules houses all the motor control electronics in a self-contained, integrated avionics compartment. Unlike the snake robots previously introduced in the academic literature, EELS is the first large scale robot (weighing about 83Kg and 4.4m in length) which has unparalleled ability to exert large forces to the environment and support its own weight, thanks to its unique high torque dense shape actuators. The paper concludes with detailed screw actuation analysis focusing on vertical mobility for EELS.