Dynamic modeling and vibration control of underwater soft-link manipulators undergoing planar motions

Underwater soft-link manipulators can be applied in offshore and marine industries. However, the soft-body link may interact with the fluid flow in this type of coupled liquid-link system. Both frequencies and mode shapes of the coupled system differ from those of uncoupled link vibrations and water flow due to the liquid-link interaction. Therefore, the dynamic model of underwater soft-body manipulators that account for liquid-link interaction is required to comprehend and control. Although significant work has been focused on the underwater manipulator and the soft manipulator, no significant dynamic modeling, control study, and experimental validation have been directed at the liquid-link interaction in underwater soft-body manipulators. A dynamic model of underwater soft-link manipulators undergoing planar motions is presented in this article. The analyses of frequencies and mode shapes for the liquid-link interaction are also described. Meanwhile, a control method is designed to mitigate coupled vibrations in underwater soft-link manipulators. Simulated and experimental results validate the utility of the dynamic model and control method.