Undulating Propulsion Research Articles

CMBUV: A Composite-Mechanism Bioinspired Underwater Vehicle Integrated With Elasticity and Shear Damping Possesses High-Performance Capability

Benefiting from the potential advantages of low noise, high efficiency and little disturbance, bionic propulsion has attracted wide attentions. Compared with the rigid structure, the performance of the elastic propulsion structure such as flexible caudal fin and passive compliant joint has been improved, yet the effective frequency range is limited due to the single mechanism. The optimal propulsion can only be produced in a certain frequency range. In this article, a biological passive peduncle joint integrated with the composite mechanism of elasticity and shear damping is proposed, solving the problem of the narrow frequency range of effective propulsive capacity. Through the optimal regulation of the elastic function at a certain frequency range and characterization of the damping function which increases with frequency, the response features of the passive joint are optimized over a wide range of frequencies, thereby improving the propulsive performance of the composite-mechanism bioinspired underwater vehicle (CMBUV). A dynamic model is built and the deformation analysis of the compliant caudal fin is carried out. The propulsive efficiency is characterized, and the results indicate that the compliant caudal fin modulates the power transmission for enhancing thrust production. Extensive simulations and experiments reveal that the CMBUV achieves both high swimming speed with 4.42 body length per second and low cost of transport with 90.33 J kg <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{-1}$</tex-math></inline-formula> m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{-1}$</tex-math></inline-formula> . Bioinspired propulsion from this study takes advantage of undulating propulsion of natural fish, offering valuable insights into performing marine tasks in ocean environments.

A CPG-based framework for flexible locomotion control and propulsion performance evaluation of underwater undulating fin platform

The black ghost knifefish is considered to possess central pattern generators (CPGs), which generates rhythms in neural circuits, coordinating the deformation of its elongated fin to achieve efficient and agile locomotion. Current biomimetic robots imitating the locomotion of the black ghost knifefish and using an undulating propulsion control method face significant challenges in adapting their swimming gaits to different environments and tasks. To overcome this limitation, this study conducted biomimetic robot research that extended from morphology to neurobiology and mimicked the CPG to construct a unified framework based on coupled Hopf oscillators. Meanwhile, an amplitude mapping function and a novel coupling method for the CPG-based control framework are proposed. The advantages of the proposed control framework are the ability to modulate different control parameters and replicate different swimming gaits, including forward, hovering, and backward swimming, realising seamless gait transitions. The control framework was tested on a specially designed undulating fin platform to evaluate the propulsion performance by modulating the control parameters, including amplitude, frequency, and phase difference. The experimental results demonstrate that the proposed CPG-based control framework achieves multimodal locomotion, enabling rapid and smooth transitions between swimming gaits, thus enhancing the robot's adaptability and stability in variable swimming environments.

Hydrodynamic performance of a biomimetic undulating fin robot under different water conditions

Inspired by the agile swimming behavior of the Black Ghost Knife Fish utilizing undulating propulsion in complex aquatic environments, this study investigates the locomotion principles and hydrodynamic performance of an undulating propulsion system under varying hydrodynamic conditions through numerical simulations and experiments. The influence of the fin aspect ratio on the thrust performance of the robot was explored, revealing a linear correlation between the aspect ratio and thrust generation. Furthermore, based on an aspect ratio of 0.3, the effects of frequency, amplitude, and wavenumber on the robot’s swimming performance were examined. The results indicated a quadratic relationship between frequency and thrust, a linear relationship between amplitude and thrust, and a trend where thrust initially increased and then decreased with wavenumber, reaching an optimal level around wavenumber 1. Using numerical simulations and experimental investigations, the thrust performance of the robot under wave conditions demonstrated a noticeable reduction in hydrodynamic performance compared to still water conditions. The effects of frequency, amplitude, and wavelength on thrust remained consistent with still water conditions, but the instantaneous thrust became unstable. The current conclusions provide valuable insights for designing and optimizing undulating propulsion robots, offering systematic guidance for selecting appropriate motion parameters to accomplish different tasks.

Underwater Undulating Propulsion Biomimetic Robots: A Review.

The traditional propeller-based propulsion of underwater robots is inefficient and poorly adapted to practice. By contrast, underwater biomimetic robots show better stability and maneuverability in harsh marine environments. This is particularly true of undulating propulsion biomimetic robots. This paper classifies the existing underwater biomimetic robots and outlines their main contributions to the field. The propulsion mechanisms of underwater biomimetic undulating robots are summarized based on theoretical, numerical and experimental studies. Future perspectives on underwater biomimetic undulating robots are also presented, filling the gaps in the existing literature.

Onto Quantifying Unsteady Propulsion Characteristics Using Momentum and Energy Control Volume Assessments

AbstractThis effort presents a novel approach to interrogate efficiency for unsteady, undulating propulsion using variable momentum and energy conservation (VMEC) assessments. These integral approaches utilize large amounts of data from computational fluid dynamics (CFD) to address present difficulties associated with separating thrust from drag associated with propelling bodies as well as potentially resolve issues associated with defining a nonzero efficiency for a body in self-propulsion. Such a fundamental issue is addressed through strategic control volume assessments of the momentum and energy conservation equations. In this work, the Method of Manufactured Solutions (MMS) is used to verify the integral-based evaluation approach and better quantify output. The MMS results indicate the method is valid and that one can separate work associated with lift and drag from the energy budget. This separation procedure provides a means to separate propulsive and drag forces. The effort then studies previously validated CFD simulations of heaving and pitching foils to provide insight associated with separating axial forces into their thrust and drag components for highly complex systems. The effort then presents a new efficiency metric that can obtain nonzero efficiencies in self-propulsion. Overall, the results indicate that energy-based assessments provide insight that is a step forward toward isolating loss from propulsive mechanisms and developing proper metrics of efficiency.

Study of an Underwater Robot with an Undulating Propulsion Fin

The article is devoted to the study and analysis of the mechanism of undulating propulsion in the case of its application in underwater robots. It gives a brief review of studies related to developing a mathematical model of the movement of an underwater robot. Robot using two-symmetry undulating fin. This mathematical model imitates the movement of some fish species, such as batoid rays. The purpose of the study was to substantiate the possibility of creating a propulsion mechanism. In this mechanism the undulating movement of the fin is provided by individual elements controlled by servomotors. With appropriate control, these movements provide the propagation of the wave in the flexible fin of the robot. The advantage of this approach is a significant increase in the maneuverability of the device compared to existing traditional models. Also, the movement becomes almost silent. The experiments performed on a robot prototype. As a result, a relation is found between the parameters of the undulating movement and the linear speed and thrust of each fin. The parameters of undulating movement such frequency and amplitude are analyzed, to provide stable movement of the underwater robot. The experiments confirmed the possibility of implementing the proposed control method. They Showed the possibilities of controlling the direction of propulsion force by changing oscillating phase of each fin ray. Also, the possibilities of controlling the thrust of the fin by changing the amplitude and frequency of undulating movement of the fin.

Propulsion System Analysis Based on Particle Image Velocimetry Method in Biomimetic Unmanned Underwater Vehicle

The article presents a laboratory stand for direct measurement of the thrust generated by the undulating propulsion system of a biomimetic underwater vehicle. The laboratory water tunnel enables research and comparison of the generated thrust with the results of the fin and fluid interaction analysis using the Particle Image Velocimetry method. The water tunnel is equipped with an industrial camera for recording changes in the position of markers highlighted with a line laser in the area of analysis. The comparison of the results obtained by the PIV method with the industrial force sensor allows for the analysis of the efficiency of the biomimetic propulsion system as a function of both design and control parameters.

Fish-like shaped robot for underwater surveillance and reconnaissance – Hull design and study of drag and noise

Undulating propulsion is promising solution for underwater vehicles used in subsea security systems, especially due to its low noise, better energetic efficiency, low water turbulence and living animals mimicry. The design of the biomimetic autonomous underwater vehicle (BAUV) for intelligence surveillance and reconnaissance (ISR), built in the SABUVIS project, is presented in the paper. The shape of the vehicle hull was inspired by living fish. Key aspects of the design and construction of BAUV needed to achieve tasks required to be performed by the robot are described. Two research questions are stated in the paper: how big drag forces act on a biomimetic underwater vehicle and how mechanical design influences the noise level generated by the vehicle. To answer these questions vehicle forward velocity, hull drag, added mass and generated noise were investigated. Forces acting on the BAUV hull while being pulled forward and sideways were measured. Noise generated by the vehicle was also measured for two types of propulsors’ drives in order to select those with the lower sound pressure level. Quantitative results of drag and noise obtained in the research are important for designers of mechanical structures of useful, full scale biomimetic underwater robots and their control subsystems.

Parameters Identification of the Flexible Fin Kinematics Model Using Vision and Genetic Algorithms

Abstract Recently a new type of autonomous underwater vehicle uses artificial fins to imitate the movements of marine animals, e.g. fish. These vehicles are biomimetic and their driving system is an undulating propulsion. There are two main methods of reproducing undulating motion. The first method uses a flexible tail fin, which is connected to a rigid hull by a movable axis. The second method is based on the synchronised operation of several mechanical joints to imitate the tail movement that can be observed among real marine animals such as fish. This paper will examine the first method of reproducing tail fin movement. The goal of the research presented in the paper is to identify the parameters of the one-piece flexible fin kinematics model. The model needs further analysis, e.g. using it with Computational Fluid Dynamics (CFD) in order to select the most suitable prototype for a Biomimetic Underwater Vehicle (BUV). The background of the work is explained in the first section of the paper and the kinematic model for the flexible fin is described in the next section. The following section is entitled Materials and Methods, and includes a description of a laboratory test of a water tunnel, a description of a Vision Algorithm (VA)which was used to determine the positions of the fin, and a Genetic Algorithm (GA) which was used to find the parameters of the kinematic fin. In the next section, the results of the research are presented and discussed. At the end of the paper, the summary including main conclusions and a schedule of the future research is inserted.

The concept of a quiet undulating propulsion with ionic polymer-metal composites in autonomous underwater vehicles

Purpose: Recent years have shown a dynamic development of underwater robotics. Autonomous biomimetic underwater vehicles (BUVs) with undulating propulsion are the latest branch in this area. They imitate not only the construction of underwater living organisms such as fish, but also kinematics of their motion. Such solution gives more energy efficient propulsion with less noise comparing to classical propulsion based on screw propellers [1]. However even the latest solutions still use the same electromagnetic engines to drive those sophisticated constructions. This article contains the concept of a ionic polymer-metal composites drive, design for undulating propulsion. Design/methodology/approach: Design of the new type of fin requires further tests and presented model takes under the consideration influence of only few factors described in this paper. Findings: Results of the research confirm theoretical behaviour of IPMC’s (Ionic Polymer- Metal Composites) and show some disadvantages of this type of materials. Research limitations/implications: The effects of the research are limited to macroscopic observation with limited accuracy. Practical implications: Results of the research show possible future application of IPMC’s (in underwater robotics). Originality/value: Results of this research opens a new idea which with further tests may result in developing a new quiet undulating propulsion for BUV’s.

Thrust Measurement of Biomimetic Underwater Vehicle with Undulating Propulsion

Abstract In the recent years, a dynamical development of an underwater robotics has been noticed. One of the newest group of underwater robots are biomimetic underwater vehicles. These vehicles are driven by undulating propulsion imitating fins of underwater creatures, e.g. a fish, a seal, etc. This paper undertakes problem of thrust measurement of new biomimetic underwater vehicle equipped with undulating propulsion. At the beginning, the stand for thrust measurement is described. Then, two constructions of BUVs imitating a fish and a seal are presented. Further, the results of thrust measurement for two different undulating propulsions are inserted. At the end of the paper containing conclusions from performed measurements and foreseen research is included.

Report on Research with Biomimetic Autonomous Underwater Vehicle — Navigation and Autonomous Operation

Abstract The paper presents the second part of the final report on all the experiments with biomimetic autonomous underwater vehicle (BAUV) performed within the confines of the project entitled ‘Autonomous underwater vehicles with silent undulating propulsion for underwater ISR’, financed by Polish National Center of Research and Development. The report includes experiments on the swimming pool as well as in real conditions, that is, both in a lake and in the sea. The tests presented in this part of the final report were focused on navigation and autonomous operation.

Report on Research with Biomimetic Autonomous Underwater Vehicle — Low Level Control

Abstract The paper presents the first part of the final report on all the experiments with biomimetic autono-mous underwater vehicle (BAUV) performed within the confines of the project entitled ‘Autonomous underwater vehicles with silent undulating propulsion for underwater ISR’, financed by Polish National Center of Research and Development. The report includes experiments in the swimming pool as well as in real conditions, that is, both in a lake and in the sea. The tests presented in this part of the final report were focused on low-level control.

Development of CyberFish – Polish Biomimetic Unmanned Underwater Vehicle BUUV

Paper presents gradual progress in the development of biomimetic mobile underwater robot with undulating propulsion starting from the rugged but functional first version of CyberFish through very agile and manoeuvrable second and third version till fifth one – accurately imitating real fish. Trends in BUUV technology is briefly described in the introduction. The second and third sections describe previous, and actual state of CyberFish project successfully carried out at Cracow University of Technology and focusing on the succeeding robots design and construction. Paper is summarized with problems of the BUUV technology development yet to be solved.

전산유체역학 기법을 이용한 물고기 유영에 관한 연구

The aim of the present study is to investigate the flow interference between two adjacent undulating fish-like body, and its effect on the undulating propulsion. For this purpose, unsteady two dimensional incompressible flow calculations were conducted using an unstructured mesh flow solver, coupled with an overset mesh technique. To deal with mesh deformation due to fish locomotion, spring analogy is utilized. The fish body used in the simulation is constructed from the NACA0012 airfoil. The study indicates that the propulsion of undulating fish is proportional to frequency and wavelength of the midline oscillation when there is no adjacent fish. It also reveals that average thrust was increased when the vortex shedding from the tail was conserved well and pressure difference between upper and lower sides of the fish was magnified due to flow interference. From this study, which relative position and phase difference of locomotion between two fishes can generate maximum thrust was known among six different cases.

1P1-E05 圧電繊維複合材料を用いた生物模倣型ソフト水中ロボットの研究開発 : ウミヘビ型ロボットの試作(水中ロボット・メカトロニクス(2))

Aimming to design a soft robotic fish for more flexible and efficient fish-like motion by biomimetic method, we are developing a snake-like robot with body undulating propulsion using the piezoelectric fiber composite (PFC) as soft actuator by mimicking the sea snake. Due to the large deformation of flexible structure and complicated dynamics with fluid, the design method for soft fish robots has not been established, and we need to study it by considering the coupling between them. In this paper, the sea snake-like robot using PFC is developed by the analytical simulation with considering the coupling between flexible structure and fluid. The efficient body undulating propulsion based on meandering motion is realized successfully from the prototype, and its swimming efficiency is similar to the real sea snake's.

Dynamic Modelling of a CPG-Controlled Amphibious Biomimetic Swimming Robot

This paper focuses on the modelling and control problems of a self-propelled, multimodal amphibious robot. Inspired by the undulatory body motions of fish and dolphins, the amphibious robot propels itself underwater by oscillations of several modular fish-like propelling units coupled with a pair of pectoral fins capable of non-continuous 360 degree rotation. In order to mimic fish-like undulating propulsion, a control architecture based on Central Pattern Generator (CPG) is applied to the amphibious robot for robust swimming gaits, including forward and backward swimming and turning, etc. With the simplification of the robot as a multi-link serial mechanism, a Lagrangian function is employed to establish the hydrodynamic model for steady swimming. The CPG motion control law is then imported into the Lagrangian-based dynamic model, where an associated system of kinematics and dynamics is formed to solve real-time movements and, further, to guide the exploration of the CPG parameters and steady locomotion gaits. Finally, comparative results between the simulations and experiments are provided to show the effectiveness of the built control models.

Conception of Research on Bionic Underwater Vehicle with Undulating Propulsion

Fish-like swimming has been attracting scientists and engineers attention since many years resulting in attempts of mathematical description of fish movement and its implementation in many interesting prototypes of underwater vehicles. In this paper, conception of research on simulation, implementation and control of bionic underwater vehicle BUV with undulating propulsion is presented. In the next sections, introduction and mathematical model of bionic underwater vehicle motion are included. Then, the last implementation of the robotic fish called CyberFish, which movement is based on the presented mathematic description is presented and shortly described. In the last sections, conception of research on control system of BUV and conclusions are presented.

Numerical Visualization of Flow around Oscillating Caudal Fin

The hydrodynamics and undulating propulsion of were studied using a newly developed two-dimensional finite difference method. The mechanism of thrust generation associated with the oscillating caudal fin is discussed. In this paper, the equations of motion are solved together with the incompressible flow to simulate the flow field induced by the undulate motions. In order to investigate flow/structure interaction varies with time, the analysis is performed on the moving meshes. The arbitrary Lagrangian–Eulerian (ALE) method is applied to the Navier-Stokes equations. Grid points are generated along with the fish camber line by using algebraic method at each time step. The results of these computation shows that the kinematics of oscillating caudal fin produces a jet-stream propulsion between inverse Karman vortex with high propulsive efficiency. Investigation of the effect of Reynolds number indicates that the turning radius increases with increasing Reynolds number with no ceiling in generating the jet-stream propulsion.

A computational fluid dynamics study of tadpole swimming

The hydrodynamics and undulating propulsion of tadpoles were studied using a newly developed two-dimensional computational fluid dynamics (CFD) modeling method. The mechanism of thrust generation associated with the flow patterns during swimming is discussed. Our CFD analysis shows that the kinematics of tadpoles is specifically matched to their special shape and produces a jet-stream propulsion with high propulsive efficiency, as high as that achieved by teleost fishes. Investigation of the effect of Reynolds number indicates that the Froude efficiency increases with increasing Reynolds number with no ceiling in generating the jet-stream propulsion. Further studies using tadpole- and fish-shaped models with hindlimbs added to their body profiles reveal that the tadpole shape &shy; a globose head with a tapered tail and hindlimbs at the base of the tail &shy; allows tadpoles, but not fish, to develop hindlimbs with very little handicap on propulsion. The shapes and kinematics of tadpoles appear to be specially adapted to the requirement of these organisms to transform into frogs.