Bio-inspired Continuous Elastic Undulatory Fin for Underwater Robots Propulsion

To overcome the limitations of traditional propeller-driven systems, such as their susceptibility to entanglement with aquatic plants and potential disruption to ecosystems, we explore an alternative bio-inspired propulsion approach. The robotic fin prototype made of continuous elastic material, demonstrating its ability to generate thrust in water through undulatory motion, which is environmentally friendly. Using the natural tendency of a constrained elastic fin to adopt a shape that minimizes the elastic energy, we employ a simple mechanism to induce its undulatory motion. Using the Rigid Body and Spring Model (RBSM) for kinematic analysis, we develop a thrust calculation model to evaluate the influence of key fin kinematic parameters, such as frequency and amplitude, on thrust generation. To validate our approach, we measured the thrust produced by the fin prototype with a force sensor in the pool. The experimental results closely aligned with simulations, providing valuable insights for the future development of bio-inspired underwater robots.