Dynamics and control of underwater manipulators considering interaction between soft-body link and fluid flow

While significant work has been directed at dynamics and control of underwater soft-body manipulators, less success has been achieved with interaction between soft structures and fluid flow. The complicated behavior of the interaction may corrupt operational efficiency and safety of underwater manipulators. The equations of the motion of underwater soft-link manipulators are reported in this article. The interaction among the water flow, the lateral vibrations and vortex-induced vibrations of the soft link has been described thoroughly in the analytical model. Furthermore, a novel control method is proposed to suppress coupled vibrations induced by the interaction. Comparing with previous control methods, the proposed method can provide more robustness to variations in the design frequency. Numerous experimental data obtained from a soft-body link implanted in water validated the behavior of the dynamic model and the effectiveness of the vibration-control method. The theoretical findings may also be acceptable for other types of soft-body structures immersed in the fluid.