Wake structures behind a swimming robotic lamprey with a passively flexible tail

The vertical tail buffet induced by the vortex breakdown flow is numerically investigated. The unsteady flow is calculated by solving the RANS equations. The structural dynamic equations are decoupled in the modal coordinates. The radial basis functions (RBFs) are employed to generate the deformation mesh. The buffet response of the flexible tail is predicted by coupling the three sets of equations. The results show that the presence of asymmetry flow on the inner and outer surface of the tail forced the structural deflection offsetting the outboard. The frequency of the 2nd bending mode of the tail structure meets the peak frequency of the pressure fluctuation upon the tail surface, and the resonance phenomenon was observed. Therefore, the 2nd bending responses govern the flow field surrounding the vertical tail. Finally, the displacement of the vertical tail is small, while the acceleration with a large quantitation forces the vertical tail undergoing severe addition inertial loads.

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Dynamic modeling and experiment of a fish robot with a flexible tail fin

Journal of Bionic Engineering ◽

10.1016/s1672-6529(13)60197-3 ◽

2013 ◽

Vol 10 (1) ◽

pp. 39-45 ◽

Cited By ~ 8

Author(s):

Phi Luan Nguyen ◽

Van Phu Do ◽

Byung Ryong Lee

Keyword(s):

Dynamic Modeling ◽

Fish Robot ◽

Flexible Tail

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Performance Assessment and Actuator Design of a Flexible Tail Propulsor in an Artificial Alligator

ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, Volume 1 ◽

10.1115/smasis2010-3841 ◽

2010 ◽

Author(s):

Michael Philen ◽

Wayne Neu

Keyword(s):

Hydrodynamic Model ◽

Smart Materials ◽

Preliminary Analysis ◽

Artificial Muscle ◽

Electroactive Polymer ◽

Flexible Tail ◽

Actuation System ◽

Resistive Forces ◽

Flexible Matrix Composite ◽

Actuator Design

The overall objective of this research is to develop analysis tools for determining actuator requirements and viable actuator technology for design of a flexible tail propulsor in an artificial alligator. A simple hydrodynamic model that includes both reactive and resistive forces along the tail is proposed and the calculated mean thrust agrees well with conventional estimates of drag. Using the hydrodynamic model forces as an input, studies are performed for a 1.5 m alligator having 5 antagonistic pairs of actuators distributed along the length of the tail. As a result of the large amplitude of the tail motion, large actuator forces and strains are required for an alligator swimming at speeds 0.3 to 1.8 body lengths/s. Several smart materials are considered for the actuation system, and preliminary analysis results indicate that the acrylic electroactive polymer and the flexible matrix composite actuators are potential artificial muscle technologies for the system.

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Magnetic dipole with a flexible tail as a self-propelling microdevice

Physical Review E ◽

10.1103/physreve.85.041502 ◽

2012 ◽

Vol 85 (4) ◽

Cited By ~ 9

Author(s):

Rūdolfs Livanovičs ◽

Andrejs Cēbers

Keyword(s):

Magnetic Dipole ◽

Flexible Tail

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Flexible Tail Lamp Design

ATZ worldwide ◽

10.1007/s38311-015-0158-y ◽

2015 ◽

Vol 117 (2) ◽

pp. 16-19

Author(s):

Jaehong Kim ◽

Yanggi Lee ◽

Sewook Oh ◽

Jeonggyu Yang

Keyword(s):

Flexible Tail

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Dynamic Modeling of Robotic Fish With a Base-Actuated Flexible Tail

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4028056 ◽

2014 ◽

Vol 137 (1) ◽

Cited By ~ 24

Author(s):

Jianxun Wang ◽

Philip K. McKinley ◽

Xiaobo Tan

Keyword(s):

Hydrodynamic Force ◽

Beam Theory ◽

Small Deformation ◽

Robotic Fish ◽

Free Swimming ◽

Flexible Tail ◽

In Series ◽

Optimization And Control ◽

And Control ◽

Body Theory

In this paper, we develop a new dynamic model for a robotic fish propelled by a flexible tail actuated at the base. The tail is modeled by multiple rigid segments connected in series through rotational springs and dampers, and the hydrodynamic force on each segment is evaluated using Lighthill's large-amplitude elongated-body theory. For comparison, we also construct a model using linear beam theory to capture the beam dynamics. To assess the accuracy of the models, we conducted experiments with a free-swimming robotic fish. The results show that the two models have almost identical predictions when the tail undergoes small deformation, but only the proposed multisegment model matches the experimental measurement closely for all tail motions, demonstrating its promise in the optimization and control of tail-actuated robotic fish.

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