Analysis of Station Keeping Performance of an Underwater Legged Robot

Remotely operated vehicles (ROVs) can exploit contact with the substrate to enhance their station keeping capabilities. A negatively buoyant underwater legged robot can perform passive station keeping, relying on the frictional force to counteract disturbances acting on the robot. Unlike conventional propeller-based ROVs, this approach has similar, slightly higher efficiency while reducing disturbances to the substrate. Detailed analysis on the passive station keeping performance of an underwater legged robot was performed using Seabed Interaction Legged Vehicle for Exploration and Research 2 (SILVER2) as a reference platform, investigating the effect of leg configuration, net weight, and the nature of the substrate on station keeping performance. A numerical model was developed to study the effect of both geometrical and physical parameters on the station keeping performance, which accurately predicted the station keeping behavior of the robot during field tests. Finally, we defined a metric called station keeping efficiency for the evaluation of station keeping performance; the underwater legged robots showed higher station keeping efficiency (28%) than commercial propeller-based ROVs (11%), showing they could present an alternative for tasks such as environmental monitoring.