Optimization of RoboIguana’s Swimming Propulsion System : A Novel Engineering Approach to Bioinspired Robotic Design

Sammanfattning

Underwater robotics, particularly Remotely Operated Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs), have been increasingly used for marine exploration but often disturb marine ecosystems. To minimize this impact, RoboIguana, a bioinspired robot designed to replicate the anguilliform swimming of the Galápagos marine iguana, is being developed. Achieving such locomotion typically requires numerous actuators, but this project focuses on an innovative approach that uses only two actuators, relying on heave and pitch actuation to mimic the undulatory motion of the tail. This thesis aims to optimize RoboIguana’s swimming propulsion system through simulated experiments. By relating the flexibility of the tail’s connecting sheet to its torsional stiffness, the system’s control parameters (frequency, heave amplitude, pitch amplitude, and phase shift) and morphological parameters (tail stiffness and density) were derived. The aim was to achieve stable motions suitable for the fabricated tail. Simulations conducted in both vacuum and underwater environments identified appropriate materials and ranges of control parameters that result in stable behaviour. Smaller subsets of control parameters, which maximized propulsion force and minimized sideslip, were also identified. The thesis demonstrated that the desired anguilliform locomotion could be accomplished with minimal actuation. The results provide a solid theoretical foundation for fabricating RoboIguana’s tail and further refine the design for future physical tests. This work advances bioinspired underwater robotics by offering a novel approach to propulsion system design, optimizing hardware and production costs while minimizing material waste. Additionally, reducing the number of actuators mitigates environmental disturbances and contributes to more sustainable manufacturing.