An Omnidirectional Robotic Platform with a Vertically Mounted Manipulator for Seabed Operation

Abstract

Water visibility is a critical matter for underwater robots during operations, both for getting clear views of the environment, and as a calm and disturbance-free operating region for the manipulators to perform sampling or other operations. In reality, calm and clear water is not only restricted by the natural conditions, but also often hindered by the propeller operations from the robots themselves. Frequent gesture adjustments during manipulator operations are particularly stir-inducing from state-of-the-art underwater manipulative robots. In this work, tackling the flow disturbance issue, a novel underwater robotic platform was proposed with a jellyfish-inspired holonomic platform driven by propellers, a flow-deflection middle layer as an adjustable isolation, and a soft-robotic manipulator mounted below the bottom for operations. Compared with state-of-the-art works, the proposed platform achieved holonomic underwater locomotion with the vertical main direction having significantly reduced flow resistance; the flow-deflection layer could create a flow-calm region of 18.5 times larger underneath for the manipulator operations. A prototype robot was fabricated, and tested in closed- and open-water conditions. Results were compared to flow-simulation results with good agreements, verifying that the proposed jellyfish-inspired robotic concept was effective in both asymmetric underwater locomotion and reducing water disturbances for underwater manipulator operations.