A bio-inspired helically driven self-burrowing robot

Autonomous subsurface applications (e.g., construction, exploration, and environmental monitoring) have created a need for burrowing mechanisms and robots. This study presents a bio-inspired burrowing robot and explores its burrowing behavior (in terms of speed, acceleration, energetics, and cost of transport) in glass beads used as a sand analog. The robot has two main segments: an anchoring central body and a screw driving body. Two different screw designs (a one- and four-bladed screw) and three different anchoring fins (a dichotomous, tubercled, and control fin) were tested. It was observed that while the four-bladed screw provides a higher translational velocity, it came at the expense of higher motor torque and power, making the cost of transport high. It was also discovered that operating the one-bladed screw at a lower rotational speed provided a lower cost of transport both when burrowing in and out. In addition, the tubercled fin design showed promising results for decreasing vertical drag and, thus, increasing the translational velocity as the robot burrows into the granular media. The knowledge gained through this series of experiments will assist in the optimization of effective burrowing robots for geotechnical and geoenvironmental applications such as site investigation and environmental monitoring.