To Boldly Go Where No Robots Have Gone Before – Part 3: Characterizing the Performance of Screw Propulsion for Robust Surface and Subsurface Mobility of EELS on Highly Unknown Terrains

The Extant Exobiology Life Surveyor EELS system is a snake-like robot, with active skin screw propulsion, composed of a series of repeating segments, each housing both the actuation and propulsion mechanisms. By displaying versatile adaptability to different types of terrains, the EELS robot has the potential of exploring challenging and highly unknown environments such as the erupting vents of the Saturnian moon Enceladus, and ultimately search for extant life. The greatest source of uncertainty for robots exploring unknown environments such as EELS arises from the complex mechanical interaction with different terrains, ranging from solid surfaces (e.g., ice) to unconsolidated granular media. To mitigate this challenge, we developed, simulated, and experimentally tested a novel screw mobility system for the EELS robot that enables it to achieve dependable traction while allowing for useful controllability on both horizontal and vertical terrains with a wide range of surface conditions. This paper aims to provide detailed insights that will inform the current and future iterations of screw design for the EELS robot. Our approach involves the design of laboratory and field testbeds, and the utilization of physics-based modeling tools to analyze and comprehend the intricate mechanics governing screw movement across diverse terrains. This paper sheds light on the underlying principles and screw design considerations crucial for enhancing the EELS robot’s exploration capabilities in unknown and unpredictable environments