Dynamic Tumble Stability Analysis of a Hexapod Underwater Walking Robot

Abstract

The Crabster Robot for Mine disposal (CRM) is a hexapod underwater walking platform developed to detect and neutralize seabed mines by navigating across the ocean floor using six articulated legs and four integrated thrusters. A buoyancy control mechanism based on a compressed air system enables seamless transition between walking and propulsion modes. One of the principal challenges in subsea operation is maintaining dynamic stability under hydrodynamic disturbances, particularly the risk of tumbling. To address this, we propose an extended dynamic tumble stability margin tailored for underwater locomotion, adapted from methods originally designed for terrestrial quadrupeds. Under the assumption of a stationary robot on a flat seabed, we evaluate the influence of buoyancy and fluid dynamics on overall stability. Our findings demonstrate posture-dependent stability, with lateral flows posing less risk of tumbling than frontal currents. These results provide insights into robust operation strategies for underwater walking robots in hazardous environments.