UC San Diego

Exploration of subterranean environments, especially in a submerged state, is one ofthe most promising uses of robotics. In particular, natural environments that contain granular media are common but present various challenges for the design and control of robots. In recent years, there has been a rise in interest in robots capable of burrowing in granular media. However, most of the previous work focuses on dry granular media, and the exploration of submerged granular media still needs to be explored. Burrowing out of granular media has also yet to be explored in greater detail. Most previous systems only focused on burrowing in rather than burrowing out in conjunction with burrowing in. Here, we present a system that can burrow in and out of submerged granular media. Our system uses a tethered water jet-based fluidization approach to self-burrow in submerged granular media. We are also proposing a novel untethered volume change-based unburrowing system that works in submerged and dry granular media. We test the ability of water-jet-based fluidization to reduce the drag on the robot while moving through granular media. We further investigate the ability of the volume change mechanism to unburrow from granular media. We then also investigated design and control features to improve the ability of the robot to burrow out of granular media and validate the features experimentally.