Preliminary Study on Robotic Turning in Granular Media

Underground robots, or "burrowbots," have the potential to revolutionize undergroundexploration and study subterranean environments. The objective of this thesis is to preliminary explore a turning mechanism in burrowbots inside granular media. Building on the recent progress on bio-mimetic self-burrowing robots, specifically, inspirations were taken from both biological and engineering solutions for general angular motion over a single axis, inside granular media. The newly proposed robot draws turning inspiration from hydraulic skeleton found in organisms like earthworm, incorporating a segmented body with ball-socket joint connections that allow for greater flexibility and maneuverability like in the human spine and, using the pivot-based turning mechanism used in Tunnel Boring Machine. The focus of this thesis is on the bending and turning aspects of the robot. The design of the robot is described in detail, including the process used to assemble the segments and ball joints and including the control mechanism to initiate turning. The bending / turning capabilities of the robot are evaluated through physical testing in a controlled environment. The robot's performance is assessed in glass bead with 2 mm particle size. The results demonstrate that the robot's segmented design with the ball-socket joint connections enable it to turn inside the particulate media. This ability makes it a promising candidate for soil exploration tasks. The thesis proposes an analytical framework for the amount of torque required to rotate an elementary body (cylindrical rod) when compared to the segmented robot design, to understand the relationship of torque and angle inside granular media. In conclusion, this thesis initiates a preliminary study in the field of soil exploration through the development of a robot with a unique design inspired by biology, exploring the capabilities of an underground robot equipped with a turning mechanism that allows it to change direction. The results demonstrate that the robot is able to turn inside the media which can pave the way for future research and applications in the field of underground robotics. (Keywords: preliminary, granular media, burrowbots, ball-joint connection, segmenteddesign)