scholarly journals Hybrid metachronal rowing augments swimming speed and acceleration via increased stroke amplitude

2021 ◽  
Author(s):  
Mitchell P. Ford ◽  
William J. Ray ◽  
Erika M. DiLuca ◽  
S. N. Patek ◽  
Arvind Santhanakrishnan
Keyword(s):  
Swimming Speed ◽  
Aquatic Invertebrates ◽  
Antarctic Krill ◽  
Power Stroke ◽  
Peak Acceleration ◽  
Wake Structure ◽  
Mantis Shrimp ◽  
Burst Swimming ◽  
Recovery Stroke ◽  
Stroke Amplitude

AbstractNumerous aquatic invertebrates use drag-based metachronal rowing for swimming, in which closely spaced appendages are oscillated starting from the posterior, with each appendage phase-shifted in time relative to its neighbor. Continuously swimming species such as Antarctic krill generally use “pure metachronal rowing” consisting of a metachronal power stroke and a metachronal recovery stroke, while burst swimming species such as many copepods and mantis shrimp typically use “hybrid metachronal rowing” consisting of a metachronal power stroke followed by a synchronous or nearly synchronous recovery stroke. Burst swimming organisms need to rapidly accelerate in order to capture prey and/or escape predation, and it is unknown whether hybrid metachronal rowing can augment acceleration and swimming speed compared to pure metachronal rowing. Simulations of rigid paddles undergoing simple harmonic motion showed that collisions between adjacent paddles restrict the maximum stroke amplitude for pure metachronal rowing. Hybrid metachronal rowing similar to that observed in mantis shrimp (Neogonodactylus bredini) permits oscillation at larger stroke amplitude while avoiding these collisions. We comparatively examined swimming speed, acceleration, and wake structure of pure and hybrid metachronal rowing strategies by using a self-propelling robot. Both swimming speed and peak acceleration of the robot increased with increasing stroke amplitude. Hybrid metachronal rowing permitted operation at larger stroke amplitude without collision of adjacent paddles on the robot, augmenting swimming speed and peak acceleration. Hybrid metachronal rowing generated a dispersed wake unlike narrower, downward-angled jets generated by pure metachronal rowing. Our findings suggest that burst swimming animals with small appendage spacing, such as copepods and mantis shrimp, can use hybrid metachronal rowing to generate large accelerations via increasing stroke amplitude without concern of appendage collision.

Kinematics of Swimming in Two Species of Idotea (ISOPODA: Valvifera)

1988 ◽  
Vol 138 (1) ◽  
pp. 37-49 ◽  
Author(s):  
DAVID E. ALEXANDER
Keyword(s):  
Swimming Speed ◽  
Respiratory Function ◽  
Important Determinant ◽  
Power Stroke ◽  
Stroke Frequency ◽  
Recovery Stroke ◽  
Abdominal Appendages ◽  
Stroke Amplitude

Individuals of Idotea resecata and I. wosnesenskii were videotaped at 200 frames s−1. while swimming freely. Propulsion is provided by the first three pairs of abdominal appendages (pleopods), which may also function as gills. Unlike typical crustacean metachronal beating, in Idotea all three pairs of propulsive pleopods begin their recovery strokes simultaneously. Each pair then carries out its power stroke in sequence: third pleopods have a short power stroke, then second pleopods have an intermediate power stroke, finally first pleopods have a long power stroke. After these power strokes, there is a pause before the next recovery stroke begins. The duration of the power stroke of any pair of pleopods, as well as the overlap with other pleopods' power stroke, is variable and is not directly related to swimming speed. Stroke amplitude is approximately constant, but stroke frequency is significantly correlated with swimming speed. Other stroke variables which could affect swimming speed are also loosely correlated with frequency, but it appears that frequency is the most important determinant of swimming speed. The unusual stroke pattern in Idotea may be related to the respiratory function of the pleopods.

scholarly journals On the role of phase lag in multi-appendage metachronal swimming of euphausiids

2020 ◽  
Author(s):  
Mitchell P. Ford ◽  
Arvind Santhanakrishnan
Keyword(s):  
Swimming Speed ◽  
Large Scale ◽  
Antarctic Krill ◽  
Swimming Performance ◽  
Body Position ◽  
Phase Lag ◽  
Wake Structure ◽  
Weight Support ◽  
Metabolic Expenditure

AbstractMetachronal paddling is a common method of drag-based aquatic propulsion, in which a series of swimming appendages are oscillated, with the motion of each appendage phase-shifted relative to the neighboring appendages. Ecologically and economically important euphausiid species such as Antarctic krill (E. superba) swim constantly by stroking their paddling appendages (pleopods), with locomotion accounting for the bulk of their metabolic expenditure. They tailor their swimming gaits for behavioral and energetic needs by changing pleopod kinematics. The functional importance of inter-pleopod phase lag (ϕ) to metachronal swimming performance and wake structure is unknown. To examine this relation, we developed a geometrically and dynamically scaled robot (‘krillbot’) capable of self-propulsion. Krillbot pleopods were prescribed to mimic published kinematics of fast-forward swimming (FFW) and hovering (HOV) gaits of E. superba, and the Reynolds number and Strouhal number of the krillbot matched well with those calculated for freely-swimming E. superba. In addition to examining published kinematics with uneven ϕ between pleopod pairs, we modified E. superba kinematics to uniformly vary ϕ from 0% to 50% of the cycle. Swimming speed and thrust were largest for FFW with ϕ between 15%-25%, coincident with ϕ range observed in FFW gait of E. superba. In contrast to synchronous rowing (ϕ=0%) where distances between hinged joints of adjacent pleopods were nearly constant throughout the cycle, metachronal rowing (ϕ >0%) brought adjacent pleopods closer together and moved them farther apart. This factor minimized body position fluctuation and augmented metachronal swimming speed. Though swimming speed was lowest for HOV, a ventrally angled downward jet was generated that can assist with weight support during feeding. In summary, our findings show that inter-appendage phase lag can drastically alter both metachronal swimming speed and the large-scale wake structure.

scholarly journals Observation and analysis of diving beetle movements while swimming

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Debo Qi ◽  
Chengchun Zhang ◽  
Jingwei He ◽  
Yongli Yue ◽  
Jing Wang ◽  
...  
Keyword(s):  
Swimming Speed ◽  
High Speed ◽  
Kinematic Model ◽  
Movement Pattern ◽  
Unmanned Vehicles ◽  
Power Stroke ◽  
Cross Sectional ◽  
Motion Data ◽  
The Cross ◽  
Diving Beetle

AbstractThe fast swimming speed, flexible cornering, and high propulsion efficiency of diving beetles are primarily achieved by their two powerful hind legs. Unlike other aquatic organisms, such as turtle, jellyfish, fish and frog et al., the diving beetle could complete retreating motion without turning around, and the turning radius is small for this kind of propulsion mode. However, most bionic vehicles have not contained these advantages, the study about this propulsion method is useful for the design of bionic robots. In this paper, the swimming videos of the diving beetle, including forwarding, turning and retreating, were captured by two synchronized high-speed cameras, and were analyzed via SIMI Motion. The analysis results revealed that the swimming speed initially increased quickly to a maximum at 60% of the power stroke, and then decreased. During the power stroke, the diving beetle stretched its tibias and tarsi, the bristles on both sides of which were shaped like paddles, to maximize the cross-sectional areas against the water to achieve the maximum thrust. During the recovery stroke, the diving beetle rotated its tarsi and folded the bristles to minimize the cross-sectional areas to reduce the drag force. For one turning motion (turn right about 90 degrees), it takes only one motion cycle for the diving beetle to complete it. During the retreating motion, the average acceleration was close to 9.8 m/s2 in the first 25 ms. Finally, based on the diving beetle's hind-leg movement pattern, a kinematic model was constructed, and according to this model and the motion data of the joint angles, the motion trajectories of the hind legs were obtained by using MATLAB. Since the advantages of this propulsion method, it may become a new bionic propulsion method, and the motion data and kinematic model of the hind legs will be helpful in the design of bionic underwater unmanned vehicles.

Design and Dynamic Modeling of a Flexible Feathering Joint for Robotic Fish Pectoral Fins

2014 ◽  
Author(s):  
Sanaz Bazaz Behbahani ◽  
Xiaobo Tan
Keyword(s):  
Dynamic Model ◽  
Robotic Fish ◽  
Power Stroke ◽  
Hydrodynamic Drag ◽  
Pectoral Fin ◽  
Flexible Joint ◽  
Blade Element Theory ◽  
Pectoral Fins ◽  
Flexible Part ◽  
Recovery Stroke

In this paper, we propose a novel design for a pectoral fin joint of a robotic fish. This joint uses a flexible part to enable the rowing pectoral fin to feather passively and thus reduce the hydrodynamic drag in the recovery stroke. On the other hand, a mechanical stopper allows the fin to maintain its motion prescribed by the servomotor in the power stroke. The design results in net thrust even when the fin is actuated symmetrically for the power and recovery strokes. A dynamic model for this joint and for a pectoral fin-actuated robotic fish involving such joints is presented. The pectoral fin is modeled as a rigid plate connected to the servo arm through a pair of torsional spring and damper that describes the flexible joint. The hydrodynamic force on the fin is evaluated with blade element theory, where all three components of the force are considered due to the feathering degree of freedom of the fin. Experimental results on robotic fish prototype are provided to support the effectiveness of the design and the presented dynamic model. We utilize three different joints (with different sizes and different flexible materials), produced with a multi-material 3D printer, and measure the feathering angles of the joints and the forward swimming velocities of the robotic fish. Good match between the model predictions and experimental data is achieved, and the advantage of the proposed flexible joint over a rigid joint, where the power and recovery strokes have to be actuated at different speeds to produce thrust, is demonstrated.

The Swimming of Nymphon Gracile (Pyconogonida)

1971 ◽  
Vol 55 (1) ◽  
pp. 273-287
Author(s):  
ELFED MORGAN
Keyword(s):  
Angular Velocity ◽  
Hydrodynamic Force ◽  
Beat Frequency ◽  
High Elevation ◽  
Dorsal Side ◽  
Constant Angular Velocity ◽  
Power Stroke ◽  
Lateral Thrust ◽  
Constant Depth ◽  
Recovery Stroke

1. The organization of the swimming legs of N. gracile has been described. The legs beat ventrally so the animal swims with the dorsal side foremost. The joints between the major segments of the leg are extended for most of the power stroke, but the distal segments articulate sequentially later in the beat, commencing with the flexion of the femoro-tibial joint at the end of the power stroke. Continued flexion reduces the leg radius considerably during the recovery stroke. 2. Animals swimming at constant depth were found to have a leg-beat frequency of about 1 beat/s. Above this the rate of ascent increased rapidly with increasing frequency of beat. Abduction or adduction of the leg usually occurred prior to the start of the power stroke with the femur in the elevated position. 3. Assuming a fixed limb profile at constant angular velocity, maximum lift was calculated to have occurred with the femur inclined at an angle of about 50° to the dorso-ventral body axis. The outward component of the lateral thrust decreased to zero at this point, and with further declination of the femur the lateral forces became inwardly directed. Of the different segments of the leg, tibia 2 and the tarsus and propodium contribute most of the hydrodynamic force. 4. The angular velocity of the leg varied during the power stroke, and the actual forces generated during two beats having the same amplitude and angular velocity but of high and low elevation were calculated. Greater lift occurred during the high-elevation beat when the leg continued to provide lift throughout the power stroke, whereas the low-elevation beat acquired negative lift values towards the end of the power stroke. The lateral thrust was now directed entirely inwards.

Mechanics of Escape Responses in Crayfish (Orconectes Virilis)

1979 ◽  
Vol 79 (1) ◽  
pp. 245-263 ◽  
Author(s):  
P. W. WEBB
Keyword(s):  
Muscle Power ◽  
Total Duration ◽  
Power Stroke ◽  
Pressure Drag ◽  
Drag Forces ◽  
Added Water ◽  
Recovery Stroke ◽  
Low Efficiency ◽  
Lift Off ◽  
Tail Flip

Measurements of acceleration performance of crayfish (mean mass 0.018 kg) were made during lateral giant mediated tail flips (LG tail flips) and truncated tail flips at 15°C. The LG tail flip power stroke was composed of a lift-off phase, when crayfish accelerated vertically from the substrate, and a free swimming phase. The total duration of the power stroke was 44 ms, followed by a recovery stroke lasting 173 ms. Truncated tail flips were used in acceleration and swimming by crayfish free of the substrate. Power strokes had a mean duration of 36 ms, and recovery strokes 92 ms. Net velocities, acceleration rates, and distances travelled by the centre of mass were similar for both types of tail flips. Thrust was generated almost entirely by the uropods and telson. Velocities and angles of orientation to the horizontal of abdominal segments were similar for both types of tail flip. Angles of attack were large, varying from 30° to 90°. Pressure (drag) forces were considered negligible compared to inertial forces associated with the acceleration of added water mass. Thrust forces, energy and power were determined for exemplary tail flips. Thrust was 0.92 and 0.42 N for LG tail flip lift-off and swimming phases respectively, and 0.29 N for the swimming truncated tail flip. Rates of working were 0.39, 0.19, and 0.18 W respectively. The efficiency of converting muscle power to backward motion was estimated to be 0.5 for power strokes and 0.68 for complete swimming cycles. Comparisons with fish performance suggested fish would be less efficient (0.1-0.2). The low efficiency is attributed to energy lost in lateral recoil movements.

scholarly journals Fluid Dynamics of Biomimetic Pectoral Fin Propulsion Using Immersed Boundary Method

2016 ◽  
Vol 2016 ◽  
pp. 1-22 ◽  
Author(s):  
Ningyu Li ◽  
Yumin Su
Keyword(s):  
Fluid Dynamics ◽  
Three Dimensional ◽  
Reconstruction Algorithm ◽  
Power Stroke ◽  
Hydrodynamic Characteristics ◽  
Ring Vortex ◽  
Immersed Boundary ◽  
Pectoral Fin ◽  
Local Flow ◽  
Recovery Stroke

Numerical simulations are carried out to study the fluid dynamics of a complex-shaped low-aspect-ratio pectoral fin that performs the labriform swimming. Simulations of flow around the fin are achieved by a developed immersed boundary (IB) method, in which we have proposed an efficient local flow reconstruction algorithm with enough robustness and a new numerical strategy with excellent adaptability to deal with complex moving boundaries involved in bionic flow simulations. The prescribed fin kinematics in each period consists of the power stroke and the recovery stroke, and the simulations indicate that the former is mainly used to provide the thrust while the latter is mainly used to provide the lift. The fin wake is dominated by a three-dimensional dual-ring vortex wake structure where the partial power-stroke vortex ring is linked to the recovery-stroke ring vertically. Moreover, the connection of force production with the fin kinematics and vortex dynamics is discussed in detail to explore the propulsion mechanism. We also conduct a parametric study to understand how the vortex topology and hydrodynamic characteristics change with key parameters. The results show that there is an optimal phase angle and Strouhal number for this complicated fin. Furthermore, the implications for the design of a bioinspired pectoral fin are discussed based on the quantitative hydrodynamic analysis.

Dynamic Analysis of a Robotic Fish Propelled by Flexible Folding Pectoral Fins

Robotica ◽  
2019 ◽  
Vol 38 (4) ◽  
pp. 699-718 ◽  
Author(s):  
Van Anh Pham ◽  
Tan Tien Nguyen ◽  
Byung Ryong Lee ◽  
Tuong Quan Vo
Keyword(s):  
Power Stroke ◽  
Swimming Velocity ◽  
Force Model ◽  
Flexible Joints ◽  
Pectoral Fin ◽  
Pectoral Fins ◽  
Recovery Stroke ◽  
Turning Radius ◽  
Relationship Of ◽  
The Relationship

SUMMARYBiological fish can create high forward swimming speed due to change of thrust/drag area of pectoral fins between power stroke and recovery stroke in rowing mode. In this paper, we proposed a novel type of folding pectoral fins for the fish robot, which provides a simple approach in generating effective thrust only through one degree of freedom of fin actuator. Its structure consists of two elemental fin panels for each pectoral fin that connects to a hinge base through the flexible joints. The Morison force model is adopted to discover the relationship of the dynamic interaction between fin panels and surrounding fluid. An experimental platform for the robot motion using the pectoral fin with different flexible joints was built to validate the proposed design. The results express that the performance of swimming velocity and turning radius of the robot are enhanced effectively. The forward swimming velocity can reach 0.231 m/s (0.58 BL/s) at the frequency near 0.75 Hz. By comparison, we found an accord between the proposed dynamic model and the experimental behavior of the robot. The attained results can be used to design controllers and optimize performances of the robot propelled by the folding pectoral fins.

scholarly journals Differential regulation of Paramecium ciliary motility by cAMP and cGMP.

1988 ◽  
Vol 106 (5) ◽  
pp. 1615-1623 ◽  
Author(s):  
N M Bonini ◽  
D L Nelson
Keyword(s):  
Swimming Speed ◽  
Cyclic Nucleotides ◽  
Differential Regulation ◽  
Power Stroke ◽  
Permeabilized Cells ◽  
Ciliary Motility ◽  
Camp And Cgmp

cAMP and cGMP had distinct effects on the regulation of ciliary motility in Paramecium. Using detergent-permeabilized cells reactivated to swim with MgATP, we observed effects of cyclic nucleotides and interactions with Ca2+ on the swimming speed and direction of reactivated cells. Both cAMP and cGMP increased forward swimming speed two- to threefold with similar half-maximal concentrations near 0.5 microM. The two cyclic nucleotides, however, had different effects in antagonism with the Ca2+ response of backward swimming and on the handedness of the helical swimming paths of reactivated cells. These results suggest that cAMP and cGMP differentially regulate the direction of the ciliary power stroke.

The Mechanics of Labriform Locomotion I. Labriform Locomotion in the Angelfish (Pterophyllum Eimekei): An Analysis of the Power Stroke

1979 ◽  
Vol 82 (1) ◽  
pp. 255-271
Author(s):  
R. W. BLAKE
Keyword(s):  
Total Energy ◽  
Thrust Force ◽  
The Body ◽  
Power Stroke ◽  
Pectoral Fin ◽  
Propulsive Efficiency ◽  
Rate Of Increase ◽  
Element Approach ◽  
Total Thrust ◽  
Recovery Stroke

1. A blade-element approach is used to analyse the mechanics of the drag-based pectoral fin power stroke in an Angelfish in steady forward, rectilinear progression. 2. Flow reversal occurs at the base of the fin at the beginning and at the end of the power stroke. Values for the rate of increase and decrease in the relative velocity of the blade-elements increase distally, as do such values for hydrodynamical angle of attack. At the beginning and end of the power stroke, negative angles occur at the base of the fin. 3. The outermost 40% of the fin produces over 80% of the total thrust produced during the power stroke, and doe8 over 80% of the total work. Small amounts of reversed thrust are produced at the base of the fin during the early and late parts of the stroke. 4. The total amount of energy required during a cycle to drag the body and inactive fins through the water is calculated to be approximately 2.8 × 10−6 J and the total energy produced by the fins over the cycle (ignoring the recovery stroke) which is associated with producing the hydrodynamic thrust force, is about 1.0 × 10−5 J; which gives a propulsive efficiency of about 0.26. 5. The energy required to move the mass of a pectoral fin during the power stroke is calculated to be approximately 2.6 × 10−7 J. Taking this into account reduces the value of the propulsive efficiency by about 4% to about 0.25. The total energy needed to accelerate and decelerate the added mass associated with the fin is calculated and added to the energy required to produce the hydrodynamic thrust force and the energy required to move the mass of the fins; giving a final propulsive efficiency of 0.18.

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