RootBot: root-inspired soft-growing robot for high-curvature directional excavation

Abstract

Bio-inspired robotics garners a significant interest with an aim to improve performance and efficiency in a variety of geotechnical engineering practices. Particularly, the urban environment calls for a new robotic system that can excavate and navigate freely in the subsurface. This study presents a new soft-growing robotic system, RootBot, which exploits inspiration from plant root growth to excavate with steering and directional excavation capabilities through complicated routes and confined spaces. RootBot is designed by incorporating a locomotion mechanism modeled after the plant root growth mechanisms with excavation and discharge systems inspired by tunnel boring machines. A prototype of the RootBot demonstrates several unique features and abilities including directional excavation with a planar motion, a retractive motion, and a sharp steering ability of more than 90 & DEG; rotation with a curvature radius less than twice the width of the excavation head. A series of meter-scale experiments demonstrate that the prototype RootBot can effectively excavate and advance in wet-compacted sand. It can steer at high curvature and even pull back and quarter-turn at any point along a straight path. The RootBot is expected to be useful in various geotechnical and urban engineering practices, including directional ground excavation, navigation through a complicated, curved route to pass by unexpected underground obstacles and soil removal in inaccessible and confined spaces for buried pipe repairs.