Modeling and robust control of an eel-like robot

This thesis discusses the modeling and robust passivity-based control of an eel-like robot. The eel is modeled as a multi-body system composed of N rigid ellipsoidal segments, evolving in a perfect fluid. The effect of the added inertia is taken into account and an Euler-Lagrange formalism is used to derive the equations of motion. The model is validated against results from the literature and other results from an existing CFD code developed at Université Catholique de Louvain. Then, a robust controller exploiting the passivity properties of the system is derived in the context of input-output stability theory: a Very Strictly Passive controller is synthesized in an optimal way via Riccati equation and Kalman-Yakubovich-Popov lemma (Positive Real lemma), and the robustness of the controller is assessed by the introduction of various disturbances in the system. Finally, a Line-Of-Sight guidance block is added on top of the controller to achieve straight-line tracking, and the simulation results are compared with the literature.