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Modeling and Experimentation of a Ribbed Caudal Fin With Applications in Aquatic Robots


Presented in this study is a mathematical model and preliminary experimental results of a ribbed caudal fin to be used in an aquatic robot. The ribbed caudal tail is comprised of two thin beams separated by ribbed sectionals as it tapers towards the fin. By oscillating the ribbed caudal fin, the aquatic robot can achieve forward propulsion and maneuver around its environment. The fully enclosed system allows for the aquatic robot to have very little effect on marine life and fully blend into its respective environment. Because of these advantages, there are many applications including surveillance, sensing, and detection.

Because the caudal fin actuator has very thin side walls, Kirchhoff-Love’s large deformation beam theory is applicable for the large deformation of the fish-fin actuator. In the model, it is critical to accurately model the curvature of beams. To this end, ?! beam elements for thin beams are developed by specializing the shear- deformable beam elements, [19], based upon Reissner’s shear-deformable nonlinear beam model. Furthermore, preliminary experiments on the ribbed fin are presented to supplement the FE model.

Uses for underwater robots are widespread, impacting many engineering and commercial sectors. To achieve maximum maneuverability, several means of propulsion have been discussed and implemented in existing robots. Presented in this research is an alternative method of generating propulsion through the use of gyroscopes. Gyroscopes have been widely known as a means of stabilization or attitude control. In the work presented, a gyroscopically driven robot design is shown and validated through experiments. The robot was shown to swim along a straight path and perform both left and right 90 and 180 degree turns, allowing it to successfully maneuver along the water surface plane.

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