Design And Simulation Of A Bionic Swordfish Based On Discretization

This thesis aims to design a fish robot that is inspired by a real fish: a swordfish.In this thesis different problems have been solved.By using the Lighthill's oscillation equation to describe the swordfish trajectory,many parameters have been missed.An image analysis process has been done on a series of images in order to get the best approximation of these parameters.After getting the continuous Lighthill's equation,the other problem faced is how many links should be used to discretize the best the actual continuous curve of the trajectory.All the former projects choose this parameter randomly without any justification.During this thesis a newly thought discretization method has been developed to choose that number of links in the best optimized way.That method consists of using the radius of curvature and a threshold put on that curve in order to decide at which value of the threshold another link should be put.The error value between the discritized curve and the continuous one is assessed by using the RMS method of approximation.The method developed also gives an idea about the length that should have each link,and this method is applied to all the times t and not only for one position.The thesis ends with the spatial mechanism design of a single actuated swordfish-like robot that has 5 modules which consists of a cam transmission system that ensure the angles given to each link to mimic the real Lighthill's equation.The angular velocity of the DC motor used,is transmitted by using universal joints at each module.A simple CFD analysis has been done in 2D in order to get better idea about the thrust generation process that shows a result of 84% of efficiency.