Design Of Robotic Fish Research Articles

ANSYS Simulation of Loads Experienced by the Peduncle of a Design of Robotic Fish

Aims: This article aims at simulating the forces and dynamic load that the peduncle of a robotic fish using vulcanized natural rubber for its joint and plywood for its tail fin will experience. Methodology: Using standard strength of material equations and constitutive equation that fits the selected natural rubber, the loads that will be encountered in a water with density 990kg/m were calculated. The result was then used in ANSYS multiphysics environment to setup the simulation of the response of the peduncle to the calculated loads. Autodesk Inventor 7 was used for the geometrical drawings and calculations such as area and centroid of the non standard shape. Furthermore, the Payne effect for the rubber joint was found experimentally as its result will guide in the threshold of tail oscillation frequency allowed. Results: von Mises stress within the components of the peduncle due to the drag load was found to be 0.03kN/m to 4.64kN/m for the rubber and 0.03kN/m to 41.48kN/m for the plywood fin. Stress experienced by the peduncle under its own weight shows that for the rubber component, the maximum von Mises stress experienced by the rubber is 4.9kN/m and for the plywood material, it is 1.087kN/m. Test for warping/ bending of the peduncle shows a straight isoline pattern. Tensile stress within the epoxy bonded joints shows a uniform bond pattern. The dynamic torque experienced by the peduncle increases with frequency of oscillation and even more rapidly as the angle of swing increases though at a fixed ratio to each other. Frequency induced softening (Payne effect) shows that the rubber will become soft as the frequency reaches 25Hz. Research Article British Journal of Applied Science & Technology, 3(4): 1430-1446, 2013 1431 Conclusion: The use of plywood material for the fin and vulcanized natural rubber for the joint and using epoxy glue for the designed peduncle of the robotic fish will be capable of withstanding the stresses that will be developed in real life scenario.

Hydrodynamics of an Undulating Fin for a Wave-Like Locomotion System Design

Motivated by the interest to develop an agile, high-efficiency robotic fish for underwater applications where safe environment for data-acquisition without disturbing the surrounding during exploration is of particular concern, this paper presents computational and experimental results of a biologically inspired mechanical undulating fin. The findings offer intuitive insights for optimizing the design of a fin-based robotic fish that offers several advantages including low underwater acoustic noise, dexterous maneuverability, and better propulsion efficiency at low speeds. Specifically, this paper begins with the design of a robotic fish developed for experimental investigation and for validating computational hydrodynamic models of an undulating fin. A relatively complete computational model describing the hydrodynamics of an undulating fin is given for analyzing the effect of propagating wave motions on the forces acting on the fin surface. The 3-D unsteady fluid flow around the undulating fin has been numerically solved using computational fluid dynamics method. These numerically simulated pressure and velocity distributions acting on the undulating fin, which provide a basis to compute the forces acting on the undulating fin, have been experimentally validated by comparing the computed thrust against data measured on a prototype flexible-fin mechanism.

Bending continuous structures with SMAs: a novel robotic fish design

In this paper, we describe our research on bio-inspired locomotion systems using deformable structures and smart materials, concretely shape memory alloys (SMAs). These types of materials allow us to explore the possibility of building motor-less and gear-less robots. A swimming underwater fish-like robot has been developed whose movements are generated using SMAs. These actuators are suitable for bending the continuous backbone of the fish, which in turn causes a change in the curvature of the body. This type of structural arrangement is inspired by fish red muscles, which are mainly recruited during steady swimming for the bending of a flexible but nearly incompressible structure such as the fishbone. This paper reviews the design process of these bio-inspired structures, from the motivations and physiological inspiration to the mechatronics design, control and simulations, leading to actual experimental trials and results. The focus of this work is to present the mechanisms by which standard swimming patterns can be reproduced with the proposed design. Moreover, the performance of the SMA-based actuators’ control in terms of actuation speed and position accuracy is also addressed.

Propulsive Efficiency Analysis on C-Start of Robot Fish

For improving fast-start performance of underwater propeller, the robot fish with high maneuverability is developed using the fish-like swimming mode characterized by undulatory flexible body. Through observations of C-start in crucian carp, the kinematic model of fast-start in robot fish is set up. According to hydrodynamic analysis on unsteady effect of added mass and wake vortices, liquid reaction forces on bionic fish-body are derived. Based on simulation experiment of C-start, propulsive performance indexes including kinetic energy, power and propulsion efficiency are presented respectively. The research results can provide theoretical basis of raising propulsive efficiency of C-start in subsequent underwater experiments, and optimization design of robot fish.