Fluid force identification acting on snake-like robots swimming in viscous fluids

A snake-like robot can move in not only the dry ground but also various viscous environments of water, mud, and clay by exhibiting undulating motions. To construct numerical model including fluid–structure interaction for under above-mentioned environments, added mass drag coefficients must be identified via experimentation because they depend on shape body, roughness skin, viscosity fluid. In this work, firstly, we performed experiments which a eight links exhibits swimming motions three fluids different kinematic viscosities, measured its joint positions during swimming. Subsequently, proposed with wide range identification method some unknown fluid force parameters using an unscented Kalman filter. After that, acting method. Then, clarified that appropriate is inertia water small oil highly Moreover, confirmed undulation increased tangential along body 1.4 times. The position velocity center gravity robot, calculated models, agreed experimental results.