Using spanwise flexibility of caudal fin to improve swimming performance for small fishlike robots

2018 ◽  
Vol 30 (5) ◽  
pp. 859-871 ◽  
Author(s):  
Dan Xia ◽  
Wei-shan Chen ◽  
Jun-kao Liu ◽  
Xiang Luo
Keyword(s):  
Swimming Performance ◽  
Caudal Fin ◽  
Spanwise Flexibility

scholarly journals Swimming capability of zebrafish is governed by water temperature, caudal fin length and genetic background

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yuma Wakamatsu ◽  
Kazutoyo Ogino ◽  
Hiromi Hirata
Keyword(s):  
Water Temperature ◽  
Genetic Background ◽  
Swimming Performance ◽  
Water Velocity ◽  
Critical Swimming Speed ◽  
Adult Zebrafish ◽  
Caudal Fin ◽  
Behavioral Traits ◽  
Maximum Water ◽  
Fin Length

Abstract Several zebrafish strains such as AB, Tübingen (TU), Wild India Kolkata (WIK) and Tupfel long fin (TL) have been established for genetic study. Each strain has its morphological and behavioral traits. Motor traits, however, have not been explored in zebrafish strains. We here applied a treadmill for fish (swimmill) and measured swimming capability of adult zebrafish by critical swimming speed, which is the maximum water velocity in which fish can keep swimming. First, we confirmed that swimming capability does not vary between female and male. Second, we found that the appropriate water temperature for swimming was between 16 and 30 °C. Third, our fin clip experiments using long-finned zebrafish revealed that they can exhibit high swimming capability when the caudal fin length was set between 3 and 10 mm, implying that long-finned zebrafish are unfavorable for fast swimming. Finally, we compared swimming capability of several zebrafish strains and demonstrated that WIK fish was significantly less capable of swimming despite that they have short caudal fin (~9 mm). The offspring of WIK fish were less capable of swimming, while hybrids of WIK and TU showed high swimming performance comparable to TU. Thus, lower swimming capability of WIK strain is inheritable as a motor trait.

scholarly journals Mechanical actuator for biomimetic propulsion and the effect of the caudal fin elasticity on the swimming performance

2012 ◽  
Vol 178 ◽  
pp. 164-174 ◽  
Author(s):  
A. Apalkov ◽  
R. Fernández ◽  
J.G. Fontaine ◽  
T. Akinfiev ◽  
M. Armada
Keyword(s):  
Swimming Performance ◽  
Caudal Fin

scholarly journals Functional Morphology of Endurance Swimming Performance and Gait Transition Strategies in Balistoid Fishes

2018 ◽  
Author(s):  
Andrew B. George ◽  
Mark W. Westneat
Keyword(s):  
Aspect Ratio ◽  
High Speed ◽  
Swimming Performance ◽  
Gait Transition ◽  
Caudal Fin ◽  
Large Power ◽  
High Speeds ◽  
Transition Strategies ◽  
Body Shapes ◽  
Median Fins

AbstractTriggerfishes and filefishes (Balistoidea) use balistiform locomotion to power slow steady swimming with their dorsal and anal fins and transition to a gait dominated by body and caudal fin (BCF) kinematics at high speeds. Fin and body shapes are predicted to be strong determinants of swimming performance and the biomechanics of gait transitions. The goal of this study was to combine morphometrics and critical swimming tests to explore relationships between balistoid fin and body shapes and swimming performance in a phylogenetic context in order to understand the evolution and diversification of the balistiform swimming mode. Among the 13 species of balistoid fishes examined, fishes with high aspect ratio fins tended to achieve higher critical swimming speeds than fishes with low aspect ratio fins. Species with long, large median fins and wide caudal peduncles tended to use the balistiform gait alone for a larger percentage of their total critical swimming speed than fishes with short, small median fins and narrow caudal peduncles. Fishes on both ends of the aspect ratio spectrum achieved higher swimming speeds using the balistiform gait alone than fishes with median fins of intermediate aspect ratios. Each species is specialized for taking advantage of one gait, with balistiform specialists possessing long, large median fins capable of the large power requirements of swimming at high speeds using the median fins alone, while BCF specialists possess short, small median fins, ill-suited for powering high-speed balistiform locomotion, but narrow caudal peduncles capable of efficient caudal fin oscillations to power high-speed locomotion.Summary Statement:Geometric morphometrics reveal that fin and body shapes are good predictors of endurance swimming performance and gait transition strategies of triggerfishes and filefishes.

Neural-Based Control of Compliant Foils With Spanwise Flexibility

2019 ◽  
Author(s):  
Annika-verena Haecker ◽  
Gabriel N. Carryon ◽  
James L. Tangorra ◽  
Thomas Sattel
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
Sensory Feedback ◽  
Flexural Rigidity ◽  
Swimming Performance ◽  
Coupled System ◽  
Neural Oscillator ◽  
Feedback Signal ◽  
Spatially Varying ◽  
Spanwise Flexibility

Abstract The ability to change the spatial distribution of a compliant foil’s flexural rigidity can enhance the foil’s swimming performance capabilities but pose challenges to neural-based control of these types of foils. The same property that makes these foil’s effective propulsors also makes them challenging to control with a neural oscillator, namely the variation in the mechanical properties will cause the amplitude and phase of the sensory feedback signal to vary depending upon the placement of the sensor. In this study we investigate the effect of sensor placement on the entrainment characteristics of a coupled-system consisting of a neural oscillator driving a series of compliant foils with spanwise flexibility (i.e. spatially varying mechanical properties in the dorsal-ventral direction). We find that acquiring sensory feedback from the foil’s stiff region produces a broader range of frequencies over which entrainment occurs compared to acquiring feedback from the compliant region of a foil. Additionally, we characterize the thrust and lift forces generated by spanwise foils as a function of the foil’s flapping frequency and flexural rigidity.

Topology Optimization of the Caudal Fin of the Three-Dimensional Self-Propelled Swimming Fish

2014 ◽  
Vol 6 (06) ◽  
pp. 732-763 ◽  
Author(s):  
Zhiqiang Xin ◽  
Chuijie Wu
Keyword(s):  
Topology Optimization ◽  
Swimming Speed ◽  
Moving Boundary ◽  
Swimming Performance ◽  
Three Dimensional ◽  
The Body ◽  
Caudal Fin ◽  
Swimming Efficiency ◽  
Vorticity Flux ◽  
3D Topology

AbstractBased on the boundary vorticity-flux theory, topology optimization of the caudal fin of the three-dimensional self-propelled swimming fish is investigated by combining unsteady computational fluid dynamics with moving boundary and topology optimization algorithms in this study. The objective functional of topology optimization is the function of swimming efficiency, swimming speed and motion direction control. The optimal caudal fin, whose topology is different from that of the natural fish caudal fin, make the 3D bionic fish achieve higher swimming efficiency, faster swimming speed and better maneuverability. The boundary vorticity-flux on the body surface of the 3D fish before and after optimization reveals the mechanism of high performance swimming of the topology optimization bionic fish. The comparative analysis between the swimming performance of the 3D topology optimization bionic fish and the 3D lunate tail bionic fish is also carried out, and the wake structures of two types of bionic fish show the physical nature that the swimming performance of the 3D topology optimization bionic fish is significantly better than the 3D lunate tail bionic fish.

scholarly journals Optimum Curvature Characteristics of Body/Caudal Fin Locomotion

2021 ◽  
Vol 9 (5) ◽  
pp. 537
Author(s):  
Yanwen Liu ◽  
Hongzhou Jiang
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Swimming Performance ◽  
Beat Frequency ◽  
Reaction Force ◽  
Body Motion ◽  
Entire Body ◽  
Cost Of Transport ◽  
Caudal Fin ◽  
Swimming Mode

Fish propelled by body and/or caudal fin (BCF) locomotion can achieve high-efficiency and high-speed swimming performance, by changing their body motion to interact with external fluids. This flexural body motion can be prescribed through its curvature profile. This work indicates that when the fish swims with high efficiency, the curvature amplitude reaches a maximum at the caudal peduncle. In the case of high-speed swimming, the curvature amplitude shows three maxima on the entire body length. It is also demonstrated that, when the Reynolds number is in the range of 104–106, the swimming speed, stride length, and Cost of Transport (COT) are all positively correlated with the tail-beat frequency. A sensitivity analysis of curvature amplitude explains which locations change the most when the fish switches from the high-efficiency swimming mode to the high-speed swimming mode. The comparison among three kinds of BCF fish shows that the optimal swimming performance of thunniform fish is almost the same as that of carangiform fish, while it is better not to neglect the reaction force acting on an anguilliform fish. This study provides a reference for curvature control of bionic fish in a future time.

Effects of fin size on swimming performance, swimming behaviour and routine activity of zebrafish Danio rerio

2000 ◽  
Vol 203 (4) ◽  
pp. 813-820 ◽  
Author(s):  
I. Plaut
Keyword(s):  
Danio Rerio ◽  
Swimming Performance ◽  
Activity Level ◽  
Routine Activity ◽  
Swimming Behaviour ◽  
Water Tunnel ◽  
Activity Levels ◽  
Wild Type ◽  
Caudal Fin ◽  
No Tail

The zebrafish Danio rerio exhibits substantial morphological variability in the sizes and shapes of the body and the caudal fin. The present study describes swimming performance, swimming behaviour and routine locomotor activity patterns in three of the major morphotypes: wild-type, long-finned and no-tail. Wild-type and long-finned differ in total length (TL), fork length (FL), caudal fin length (CFL) and caudal fin height (CFH). No-tail has no caudal fin and is significantly smaller in standard length (SL) than the other types. Critical swimming speeds (U(crit)) were measured at 28 degrees C in a modified Brett-type water tunnel. U(crit) of wild-type fish was 56.0+/−4.8 cm s(−1) or 15.5 SL s(−)(1) (mean +/− s.d., N=21), significantly faster than the U(crit) of long-finned fish (43.7+/−6.8 cm s(−1) or 12.5 SL s(−1), N=17); both were significantly faster than the U(crit) of no-tail fish (19. 8+/−4.7 cm s(−1) or 6.9 SL s(−1), N=15). When forced to swim in the water tunnel, zebrafish tended to turn and swim downstream for short periods at slow water velocities. Turning frequencies (turns per minute, f(T)) at the slowest velocity (4 cm s(−1)) were 10. 1+/−6.5 min(−)(1) (N=63) and 8.6+/−4.7 min(−1) (N=51) for wild-type and long-finned, respectively, significantly different from that of the no-tail fish, 4.7+/−2.8 min(−1) (N=45). These frequencies decreased below 1 min(−1) at 56%, 64% and 61% of U(crit) in wild-type, long-finned and no-tail fish, respectively. Activity levels of wild-type fish were generally significantly higher than those of long-finned fish, and the levels of both were significantly higher than those of no-tail fish. The pattern of differences in relative activity levels between types was similar to that for U(crit). The results show that the wild-type fish, on a size-scaled basis, is one of the fastest-swimming fishes ever measured, reaching the maximum predicted theoretical sustained swimming speed. U(crit) of long-finned fish was 22% lower than that of wild-type fish, and U(crit) of no-tail fish was 65% lower. Similar differences were found in turning frequencies and routine activity level.

scholarly journals Hydrodynamics study of dolphin's self-yaw motion realized by spanwise flexibility of caudal fin

2021 ◽  
Author(s):  
Zhihan Li ◽  
Dan Xia ◽  
Jiabo Cao ◽  
Weishan Chen ◽  
Xingsong Wang
Keyword(s):  
Caudal Fin ◽  
Spanwise Flexibility
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