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

Abstract

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.

Hydrodynamics study of a BCF mode bioinspired robotic-fish underwater vehicle using Lighthill’s slender body model

“…a bellshaped curve. Therefore, it can be deduced that the kinematic results are in agreement with the hydrodynamic results for same operating ranges [20]. As seen in Fig.…”

“…Therefore, it can be deduced that the kinematic results are in agreement with the hydrodynamic results for the given operating range [20]. In contrast to the relationship between the speed and TBF in kinematics modeling in Fig.…”

Kinematic study and implementation of a bio-inspired robotic fish underwater vehicle in a Lighthill mathematical framework

“…To enhance the system repeatability therefore reliability, each parameter is plotted for various wavelengths and operating tail-beat frequency values, resulting in the operating region. Based on the simulation results discussed above, an ORE [30] that summarizes these major parameters in consideration is formed in the form of a plot as shown in Figure 9a, Figure 9c from Dewar's experiment on the biological equivalent (yellowfin tuna), shows the results of swimming velocity (cm/s) versus time. This plot also shows metabolic rate (triangular marker) trend with time as the fish moves.…”

“…parameters. This would also make it easier to operate the robot and less time consuming as the kinematic characteristic of robotic fish is presented in the form of a simple operating region chart [30]. This study stresses on the importance of major kinematic parameters while neglecting the minor parameters to avoid computational complexity.…”

Inverse dynamics control of a bio-inspired robotic-fish underwater vehicle propulsion based on Lighthill slender body theory

“…In Section II, the dynamics modeling [7,14] of a three link robotic fish is presented. Section III discusses the Lighthills slender body mathematical framework [5] and its integration with the present prototype [12,13]. This section also investigates in to the study of the different mathematical input waveforms in LH framework generating the fish undulatory motion.…”