Finding an operating region for a bio-inspired robotic fish underwater vehicle in the Lighthill framework

Sir J. Lighthill mathematical slender body swimming model formulates the biological fish propulsion mechanism (undulation) in fluid environment. The present research has focused on the relevance of Lighthill (LH) based biomimetic robotic propulsion. A 2-joint, 3-link multibody vehicle model biologically inspired by a Body Caudal Fin (BCF) carangiform fish propulsion mechanism is designed. Different mathematical propulsive waveforms are proposed in LH frame-work to generate posterior body undulation. These functions are combined with inverse kinematics to generate various bio-inspired trajectories for the robotic fish vehicle motion. The robotic fish model (kinematics and dynamics) is integrated with the Lighthill (LH) mathematical model framework. Comparative studies are undertaken among a LH model and the proposed propulsive wave models. LH Cubic and NURB quadratic functions are found to be 16.32 % and 17.94 % efficient than a non-LH function respectively. Based on the simulation results of critical kinematic parameters TBF and Propulsive wavelength, an operating region is established to facilitate the open-loop (manual) control experiments.