Review of Computational Fluid Dynamics Analysis in Biomimetic Applications for Underwater Vehicles

Biomimetics, which draws inspiration from nature, has emerged as a key approach in the development of underwater vehicles. The integration of this approach with computational fluid dynamics (CFD) has further propelled research in this field. CFD, as an effective tool for dynamic analysis, contributes significantly to understanding and resolving complex fluid dynamic problems in underwater vehicles. Biomimetics seeks to harness innovative inspiration from the biological world. Through the imitation of the structure, behavior, and functions of organisms, biomimetics enables the creation of efficient and unique designs. These designs are aimed at enhancing the speed, reliability, and maneuverability of underwater vehicles, as well as reducing drag and noise. CFD technology, which is capable of precisely predicting and simulating fluid flow behaviors, plays a crucial role in optimizing the structural design of underwater vehicles, thereby significantly enhancing their hydrodynamic and kinematic performances. Combining biomimetics and CFD technology introduces a novel approach to underwater vehicle design and unveils broad prospects for research in natural science and engineering applications. Consequently, this paper aims to review the application of CFD technology in the biomimicry of underwater vehicles, with a primary focus on biomimetic propulsion, biomimetic drag reduction, and biomimetic noise reduction. Additionally, it explores the challenges faced in this field and anticipates future advancements

Biological Propulsion Systems for Ships and Underwater Vehicles

Regulations and performance requirements related to technology development on all modes of transport vehicles for reduced pollution and environmental impact have become more stringent. Greening of transport system has been recognized as an important factor concerning global warming and climate change. Thus environment-friendly technical solutions offering a reduction of noxious exhaust gases are in demand. Aquatic animals have good swimming and maneuvering capabilities and these observations have motivated research on fish-like propulsion for marine vehicles. The fish fin movements, used by fish for their locomotion and positioning, are being replicated by researchers as flapping foils to mimic the biological system. Studies show that flapping foil propulsion systems are generally more efficient than a conventional screw propeller, which suffers efficiency losses due to wake. The flapping foil propulsors usually do not cavitate and have less wake velocity variation. These aspects result in the reduction of noise and vibration. The present study will cover an overview of aquatic propulsion systems, numerical simulations of flapping foils and ship model self-propulsion experiments performed using flapping foil system, particle image velocimetry (PIV), and digital fluoroscopy studies conducted on fish locomotion. Studies performed on underwater and surface vehicles fitted with flapping fins will also be presented

출력 토크 조절이 가능한 Scotch yoke 메커니즘

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2013. 2. 조규진.The robotic fish using servomotor was generally difficult to operate high frequency because the servo motor decreases the velocity to switch the direction of the tail fin. To solve this problem, various researchers have tried to use the Scotch yoke mechanism with DC motor for robotic fish. The Scotch yoke mechanism converts the rotating motion of motor into the reciprocating motion. However, in this mechanism, the torque of the motor with scotch yoke mechanism is changed in terms of the phase of the tail fin while the DC motor maintains the torque constantly. Thus, the objective of this paper is to regulate the motor output torque by using the adjustable Scotch yoke mechanism. This mechanism uses springs to store the motor torque and cam mechanism to release this torque at desired moment. We analyzed a kinematic model of the Scotch yoke mechanism to propose a method of designing the part of the adjustable Scotch yoke mechanism. In addition, we experiment to measure the thrust of tail fin while the equal input voltage of controller is supplied respectively and compare the conventional mechanism and adjustable Scotch yoke mechanism by considering the compliance of the fin. As a result, we conclude that the adjustable scotch yoke mechanism enables the propulsion system to improve the average thrust than conventional scotch yoke mechanism during the equivalent power consumption. Therefore, based on these result, the high speed robotic fish can be made by applying the adjustable Scotch yoke mechanism which regulated the output torque.Abstract i Contents iii List of Tables v List of Figures vi Chapter 1. Introduction 1 Chapter 2. The Propulsion System with Scotch Yoke Mechanism 5 2.1 Characteristics of the Scotch Yoke Mechanism 5 2.2 Kinematic Model of Scotch Yoke Mechanism 8 Chapter 3. Adjustable Scotch Yoke Mechanism 12 3.1 Design of Adjustable Scotch Yoke Mechanism 12 3.2 Modeling of the Crank Wheel 16 3.3 Design of the Scotch Yoke Mechanism 20 Chapter 4 Mothod 23 4.1 Experimental Procedure 23 4.2 Apparatus 25 Chapter 5. Rusults and Discussion 27 5.1 Experimental Result 27 5.2 Analysis of the Experimental Results 28 Chapter 6 Conclusion and Future Work 34 Bibliography 36 국문초록 40Maste

Aerial-aquatic robots capable of crossing the air-water boundary and hitchhiking on surfaces.

Many real-world applications for robots-such as long-term aerial and underwater observation, cross-medium operations, and marine life surveys-require robots with the ability to move between the air-water boundary. Here, we describe an aerial-aquatic hitchhiking robot that is self-contained for flying, swimming, and attaching to surfaces in both air and water and that can seamlessly move between the two. We describe this robot's redundant, hydrostatically enhanced hitchhiking device, inspired by the morphology of a remora (Echeneis naucrates) disc, which works in both air and water. As with the biological remora disc, this device has separate lamellar compartments for redundant sealing, which enables the robot to achieve adhesion and hitchhike with only partial disc attachment. The self-contained, rotor-based aerial-aquatic robot, which has passively morphing propellers that unfold in the air and fold underwater, can cross the air-water boundary in 0.35 second. The robot can perform rapid attachment and detachment on challenging surfaces both in air and under water, including curved, rough, incomplete, and biofouling surfaces, and achieve long-duration adhesion with minimal oscillation. We also show that the robot can attach to and hitchhike on moving surfaces. In field tests, we show that the robot can record video in both media and move objects across the air/water boundary in a mountain stream and the ocean. We envision that this study can pave the way for future robots with autonomous biological detection, monitoring, and tracking capabilities in a wide variety of aerial-aquatic environments

Integration of aerial and terrestrial locomotion modes in a bioinspired robotic system

In robotics, locomotion is a fundamental task for the development of high-level activities such as navigation. For a robotic system, the challenge of evading environmental obstacles depends both on its physical capabilities and on the strategies followed to achieve it. Thus, a robot with the ability to develop several modes of locomotion (walking, flying or swimming) has a greater probability of success in achieving its goal than a robot that develops only one. In nature, Hymenoptera insects use terrestrial and aerial modes of locomotion to carry out their activities. Mimicry the physical capabilities of these insects opens the possibility of improvements in the area of robotic locomotion. Therefore, this work seeks to generate a bio-inspired robotic system that integrates the terrestrial and aerial modes of locomotion. The methodology used in this research project has considered the anatomical study and characterization of Hymenoptera insects locomotion, the proposal of conceptual models that integrate terrestrial and aerial modes locomotion, the construction of a physical platform and experimental testing of the system. In addition, a gait generation approach based on an artificial nervous system of coupled nonlinear oscillators has been proposed. This approach has resulted in the generation of a coherent and functional gait pattern that, in combination with the flight capabilities of the system, has constituted an aero-terrestrial robot. The results obtained in this work include the construction of a bioinspired physical platform, the generation of the gait process using an artificial nervous system and the experimental tests on the integration of aero-terrestrial locomotion.Conacyt - Becario Naciona

Manta Ray Robot

The goal of this project was to improve UAV efficiency through use of biomimetic design. This was achieved through the application of a hydraulically actuated soft robotic fin. Drawing inspiration from the manta ray, a custom actuator was developed to achieve a feasible, lifelike locomotion method. The actuator was incorporated into a prototype robot to assess the performance and ease of integration

Optimal trajectory planning for a UAV glider using atmospheric thermals

An Unmanned Aerial Vehicle Glider (UAV glider) uses atmospheric energy in its different forms to remain aloft for extended flight durations. This UAV glider\u27s aim is to extract atmospheric thermal energy and use it to supplement its battery energy usage and increase the mission period. Given an infrared camera identified atmospheric thermal of known strength and location; current wind speed and direction; current battery level; altitude and location of the UAV glider; and estimating the expected altitude gain from the thermal, is it possible to make an energy efficient based motivation to fly to an atmospheric thermal so as to achieve UAV glider extended flight time? For this work, an infrared thermal camera aboard the UAV glider takes continuous forward-looking ground images of hot spots . Through image processing a candidate atmospheric thermal strength and location is estimated. An Intelligent Decision Model incorporates this information with the current UAV glider status and weather conditions to provide an energy-based recommendation to modify the flight path of the UAV glider. Research, development, and simulation of the Intelligent Decision Model is the primary focus of this work. Three models are developed: (1) Battery Usage Model, (2) Intelligent Decision Model, and (3) Altitude Gain Model. The Battery Usage Model comes from the candidate flight trajectory, wind speed & direction and aircraft dynamic model. Intelligent Decision Model uses a fuzzy logic based approach. The Altitude Gain Model requires the strength and size of the thermal and is found a priori