Parameters governing regolith site work by small robots

Abstract

Continued exploration of the Moon and Mars will call for mobile robots that are increasingly capable in regolith; not only traversing it without getting stuck, but also manipulating and shaping it to suit mission needs. This work distinguishes issues governing performance of regolith operations, based on tasks motivated by preparatory site work for lunar outposts. Payload ratio (pound-for-pound regolith-moving capacity) of small site work robots is identified as the key parameter governing metrics such as completion time for tasks ranging from berm building to trench digging. In addition to payload ratio, driving speed also governs berm building with small robots, while soil interaction parameters including regolith cohesion and soil-tool friction dictate trench digging performance. Furthermore, 3-dimensional bucket modeling highlights cohesion and friction as risks to the viability of using the smallest proposed class of excavation robots (those with mass of 250 kg or less). For trench digging especially, machines with higher mass (500 kg or more) may be required. Results are based on parameter sensitivity analyses using REMOTE, a task-level site work simulator.