Dynamics of a Bio-Inspired Dual-Auger Burrowing Robot in Granular Media: DEM-MBD Cosimulation with Complementary Kinematics-Controlled Tests

This study investigates the dynamics of a bioinspired dual-auger burrowing robot in granular media using a discrete element method-multibody dynamics (DEM-MBD) cosimulation approach, complemented by kinematics-controlled tests performed with pure DEM (MBD disabled) and DEM-MBD simulations. Observations indicate that when the same-handed augers rotate in the same direction, the robot primarily moves horizontally, accompanied by minor pitching and yawing motions. The stator plays a crucial role in providing antitorque by rolling in the opposite direction of the augers. Kinematics-controlled tests revealed key insights into the thrust, drag, and lift forces governing the robot’s burrowing motion, highlighting that thrust forces redistribute once the robot starts moving. Additionally, auger rotation appears to reduce drag forces, facilitating burrowing. The observed upward and pitching movements result from the uneven distribution of lift forces induced by the augers’ dragging and rotating actions. While pure DEM is suitable for kinematics-controlled scenarios, the DEM-MBD cosimulation provides a realistic, fully coupled description of burrowing mechanics by resolving both granular interactions and the robot’s rigid-body dynamics.