Undulatory ribbon- n-based propulsion is an appealing propulsion mechanism
due to its rich locomotor capabilities that can improve the propulsive performance
and maneuverability of underwater vehicles. For instance, the swimming mechanics
of weakly electric black ghost knife sh (Apteronotus albifrons) is of great interest
to study because of their high swimming e ciency at low speeds and extraordinary
agility such as rapid reversal swimming, hovering in presence of water disturbance,
rolling and vertical swimming. In this thesis work, to facilitate our understanding on
the
exible undulatory ribbon n propulsion, we have four research motivations. The
rst objective is to study how the use of
exible rays and di erent n morphology
can in
uence the propulsive performance of ribbon- n propulsion. It is possible that
natural swimmers using this locomotion method could take advantage of passive n
motion based on the coupling of
uid-structure interaction and the elasto-mechanical
responses of the undulating n. Therefore, the second objective is to understand
how an under-actuated undulating n can take advantage of natural dynamics of
the
uid-structure interaction for the propulsive force generation. In addition to the
impressive propulsive performance of the undulatory n propulsion, the exceptional maneuverability of knife sh is also a key motivation that drives this thesis work.
Thus, we dedicate to investigate how traveling wave shapes and actuation parameters
(frequency, wavelength) can manipulate the maneuvering behaviors of a swimmer
propelled by an undulating ribbon n. Lastly, we aim to uncover the e ect of varying
traveling wave amplitudes and pectoral ns on its maneuvering performances. Two
robotic devices were developed to study the propulsive performance of both fullyactuated
and under-actuated ribbon n propulsion and investigate the maneuver
control of a free-swimming underwater robot propelled by an undulatory n.
For the rst research aim, we study the e ect of
exible rays and di erent
n morphology on the propulsive performance of ribbon- n propulsion. A physical
model composed of fteen rays interconnected with an elastic membrane was used to
test four di erent ray
exural sti ness and four aspect ratios. Our results show that
exible rays can improve the propulsive e ciency compared to a rigid counterpart.
In addition, the morphology of the ribbon n a ects its propulsive performance as
well, and there could exist an optimal n morphology. To understand how an underactuated
undulating n can modify its active and passive n motion to e ectively
control the hydrodynamic force and propulsive e ciency. We did a series of experiments
using the same robotic n model but with some structural modi cations and
we measured n kinematics, net surge force and power consumption. We nd that the
under-actuated n can keep the equivalent propulsive e ciency as the fully-actuated
counterpart within our experimental parameter range. Moreover, our results demonstrate
that the thrust force and power consumption of an under-actuated n follow
the same scaling laws as the fully-actuated n.
To conduct the free-swimming maneuver study, we developed a self-contained,
free-swimming robot propelled by an undulatory n, which is able to perform the
following maneuvers: forward, reversed swimming and hovering motion. We also
performed V3V PIV experiments to capture the
ow structures generated by the robotic device. Our results show that the robot can reach higher swimming e ciency
at low frequencies. As the number of traveling waves increases, the robot swims
more stably in roll, pitch and yaw motions. For cases with varying wave amplitudes,
traveling wave with incremental wave amplitude can achieve free-swimming velocity
higher than that of decremental wave amplitude. However, the latter case can generate
higher pitch angles. For the robot with slightly negative-pitched pectoral ns,
it can perform slow diving maneuvers. These ndings demonstrate that we can take
advantage of the undulating ribbon n propulsion to achieve high maneuverability
for the future underwater vehicles in complex environment. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
| Identifer | oai:union.ndltd.org:fau.edu/oai:fau.digital.flvc.org:fau_34565 |
| Contributors | Liu, Hanlin (author), Curet, Oscar M. (Thesis advisor), Florida Atlantic University (Degree grantor), College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering |
| Publisher | Florida Atlantic University |
| Source Sets | Florida Atlantic University |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation, Text |
| Format | 146 p., application/pdf |
| Rights | Copyright © is held by the author, with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder., http://rightsstatements.org/vocab/InC/1.0/ |
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