Tunable stiffness in fish robotics: mechanisms and advantages

Bioinspiration & Biomimetics ◽

10.1088/1748-3190/ac3ca5 ◽

2021 ◽

Author(s):

Daniel B Quinn ◽

George V Lauder

Keyword(s):

Water Channel ◽

Muscular Activity ◽

Gear Ratio ◽

The Body ◽

Or Efficiency ◽

Leaf Springs ◽

Driving Speed ◽

Body Joints ◽

Optimal Stiffness ◽

Tunable Stiffness

Abstract One of the emerging themes of fish-inspired robotics is flexibility. Adding flexibility to the body, joints, or fins of fish-inspired robots can significantly improve thrust and/or efficiency during locomotion. However, the optimal stiffness depends on variables such as swimming speed, so there is no one “best” stiffness that maximizes efficiency in all conditions. Fish are thought to solve this problem by using muscular activity to tune their body and fin stiffness in real-time. Inspired by fish, some recent robots sport polymer actuators, adjustable leaf springs, or artificial tendons that tune stiffness mechanically. Models and water channel tests are providing a theoretical framework for stiffness-tuning strategies that devices can implement. The strategies can be thought of as analogous to car transmissions, which allow users to improve efficiency by tuning gear ratio with driving speed. We provide an overview of the latest discoveries about 1) the propulsive benefits of flexibility, particularly tunable flexibility, and 2) the mechanisms and strategies that fish and fish-inspired robots use to tune stiffness while swimming.

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Sea stars generate downforce to stay attached to surfaces

Scientific Reports ◽

10.1038/s41598-021-83961-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mark Hermes ◽

Mitul Luhar

Keyword(s):

Body Shape ◽

Control Volume ◽

Water Channel ◽

Morphological Plasticity ◽

The Body ◽

Sea Star ◽

Sea Stars ◽

Hydrodynamic Loads ◽

Spherical Dome ◽

Star Models

AbstractIntertidal sea stars often function in environments with extreme hydrodynamic loads that can compromise their ability to remain attached to surfaces. While behavioral responses such as burrowing into sand or sheltering in rock crevices can help minimize hydrodynamic loads, previous work shows that sea stars also alter body shape in response to flow conditions. This morphological plasticity suggests that sea star body shape may play an important hydrodynamic role. In this study, we measured the fluid forces acting on surface-mounted sea star and spherical dome models in water channel tests. All sea star models created downforce, i.e., the fluid pushed the body towards the surface. In contrast, the spherical dome generated lift. We also used Particle Image Velocimetry (PIV) to measure the midplane flow field around the models. Control volume analyses based on the PIV data show that downforce arises because the sea star bodies serve as ramps that divert fluid away from the surface. These observations are further rationalized using force predictions and flow visualizations from numerical simulations. The discovery of downforce generation could explain why sea stars are shaped as they are: the pentaradial geometry aids attachment to surfaces in the presence of high hydrodynamic loads.

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The history of anabolic steroids and a review of clinical experience with anabolic steroids

Acta Endocrinologica ◽

10.1530/acta.0.109s00011 ◽

1985 ◽

Vol 110 (3_Suppla) ◽

pp. S11-S18 ◽

Cited By ~ 50

Author(s):

H. Kopera

Keyword(s):

Protein Synthesis ◽

Protein Metabolism ◽

Anabolic Steroids ◽

Muscular Activity ◽

Living Cells ◽

Cellular Protein ◽

Complex Compounds ◽

The Body ◽

Anabolic Effect ◽

Vital Functions

Metabolism is the term employed to embrace the various physical and chemical processes occurring within the tissues upon which the growth and heat production of the body depend and from which the energy for muscular activity, for the maintenance of vital activity and for the maintenance of vital functions is derived (Best & Taylor 1950). The destructive processes by which complex substances are converted by living cells into more simple compounds are called catabolism. Anabolism denotes the constructive processes by which simple substances are converted by living cells into more complex compounds, especially into living matter. Catabolism and anabolism are part of all metabolic processes, the carbohydrate, fat and protein metabolism. The term anabolic refers only to substances that exert an anabolic effect on protein metabolism and are unlikely to cause adverse androgenic effects. They shift the equilibrium between protein synthesis and degradation in the body as a whole in the direction of synthesis, either by promoting protein synthesis or reducing its breakdown. The protein anabolic effect of anabolic steroids is not restricted to single organs but is the result of stimulated biosynthesis of cellular protein in the whole organism.

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Boundaries Influence on the Flow Field Around an Oscillating Sphere

Volume 7: CFD and VIV ◽

10.1115/omae2013-11385 ◽

2013 ◽

Cited By ~ 3

Author(s):

Domenica Mirauda ◽

Antonio Volpe Plantamura ◽

Stefano Malavasi

Keyword(s):

Free Surface ◽

Flow Field ◽

Boundary Conditions ◽

Damping Ratio ◽

Water Channel ◽

Open Water ◽

Free Surface Flows ◽

The Body ◽

Sphere Diameter ◽

Oscillating Sphere

This work analyzes the effects of the interaction between an oscillating sphere and free surface flows through the reconstruction of the flow field around the body and the analysis of the displacements. The experiments were performed in an open water channel, where the sphere had three different boundary conditions in respect to the flow, defined as h* (the ratio between the distance of the sphere upper surface from the free surface and the sphere diameter). A quasi-symmetric condition at h* = 2, with the sphere equally distant from the free surface and the channel bottom, and two conditions of asymmetric bounded flow, one with the sphere located at a distance of 0.003m from the bottom at h* = 3.97 and the other with the sphere close to the free surface at h* = 0, were considered. The sphere was free to move in two directions, streamwise (x) and transverse to the flow (y), and was characterized by values of mass ratio, m* = 1.34 (ratio between the system mass and the displaced fluid mass), and damping ratio, ζ = 0.004. The comparison between the results of the analyzed boundary conditions has shown the strong influence of the free surface on the evolution of the vortex structures downstream the obstacle.

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Control System for the Mountainous Orchard Electric-Drive Monorail Transporter

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.738-739.935 ◽

2015 ◽

Vol 738-739 ◽

pp. 935-940 ◽

Cited By ~ 1

Author(s):

Zhen Li ◽

Pei Xu ◽

Yu Ping Ouyang ◽

Shi Lei Lv ◽

Qiu Fang Dai

Keyword(s):

Control System ◽

Electric Drive ◽

Gear Ratio ◽

System A ◽

Speed Measurement ◽

Driving Speed ◽

Current Consumption ◽

Operation Risk ◽

Load Weight ◽

Steep Hill

In order to reduce operation risk and working intensity in mountainous orchard transportation and to realize optimized control for the mountainous orchard electric-drive monorail transportation system, a mountainous orchard electric-drive monorail transporter control system was designed and developed in this study. The system mainly consists of modules as: manual and remote control, positioning, obstacle avoidance, speed measurement, motor control, electric-magnetic break, and the position limit. The driving speed, current consumption, break control, and battery pack running ability experiments were conducted to test the control system. Results indicated that, the transporter’s driving speed is 0.60~0.58 m/s when it is running on the ground with the load weight from 0 to 100kg. This speed is little affected by the load weight. The transporter’s driving speed is 0.45~0.28 m/s when it is climbing a steep hill with an angle of 39°. That speed is critically affected by the load weight. In further improvements, a shift mechanism will be introduced so that adjustable gear ratio could be achieved thus solve the current overload problem in a full load situation.

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The Oxygen Consumption of an Echiuroid, Bonellia Viridis Rolando

Journal of Experimental Biology ◽

10.1242/jeb.48.2.427 ◽

1968 ◽

Vol 48 (2) ◽

pp. 427-434

Author(s):

A. E. BRAFIELD

Keyword(s):

Oxygen Consumption ◽

Body Size ◽

Continuous Flow ◽

Muscular Activity ◽

Dry Weight ◽

The Body ◽

Body Region ◽

Rate Of Oxygen Consumption

1. The oxygen consumption of the echiuroid Bonellia viridis has been investigated by means of a continuous-flow polarographic respirometer. 2. The general rate of oxygen consumption per unit dry weight is similar to that characteristic of polychaetes, and declines exponentially with increasing body size. 3. The rate of oxygen consumption rises in the light and falls again if darkness is restored. 4. The oxygen consumption of the isolated proboscis plus that of the isolated body region corresponds closely to that of the entire animal. 5. The oxygen consumption per unit dry weight of the proboscis is considerably higher than that of the body region. 6. The oxygen consumption of an isolated body region increases in the presence of light, but that of an isolated proboscis does not. 7. These findings are discussed in relation to the biology of the animal, observed muscular activity, and the occurrence of the pigment bonellin.

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Computer Simulation for Ergonomic Bus Operator Workstation Design With Validation

Volume 2: 24th Design Automation Conference ◽

10.1115/detc98/dac-5635 ◽

1998 ◽

Author(s):

H. You ◽

B. Oesterling ◽

B. Lowe ◽

B. J. Gilmore ◽

A. Freivalds

Keyword(s):

Computer Simulation ◽

The Body ◽

Medium Size ◽

Kinematic Constraints ◽

Test Track ◽

Human Models ◽

Workstation Design ◽

Body Joints ◽

Bus Operator ◽

Simulation Package

Abstract Bus operator’s workstations neglecting ergonomic features can cause overall discomfort and injuries to the users. This paper presents use of JACK®, a human work simulation package, in designing and evaluating a bus operator workstation which can provide sufficient visibility, natural reach, and comfortable posture for operators who range from the 5th percentile female to the 95th percentile male as defined by SAE J833 (SAE, 1994). Three human models representing the two extremes and their medium size person were created and performed 15 bus operating tasks on the bus workstation implemented in JACK®. Kinematic constraints were defined between the human models and the workstation to simulate the tasks in a realistic manner. While the human models simulated the tasks, the body joints were monitored to determine if they exceeded their comfort ranges recommended by Diffrient et al. (1981) and the workstation was evaluated in terms of visibility, reach, comfort, and adjustability. After the workstation design was refined by iterative modifications and the required component adjustment ranges were determined, the workstation design was prototyped into an actual working bus. A jury of bus operators evaluated the workstation design by operating the prototype on a test track. The response from the operators indicated that the workstation would accommodate the intended population.

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Effect ofAtractylodes macrocephalaon Hypertonic Stress-Induced Water Channel Protein Expression in Renal Collecting Duct Cells

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2012/650809 ◽

2012 ◽

Vol 2012 ◽

pp. 1-11 ◽

Cited By ~ 9

Author(s):

Yong Pyo Lee ◽

Yun Jung Lee ◽

So Min Lee ◽

Jung Joo Yoon ◽

Hye Yoom Kim ◽

...

Keyword(s):

Protein Expression ◽

Collecting Duct ◽

Water Channel ◽

Immunoblot Analysis ◽

The Body ◽

Apical Plasma Membrane ◽

Diuretic Effect ◽

Hypertonic Stress ◽

Abnormal Accumulation ◽

Atractylodes Macrocephala

Edema is a symptom that results from the abnormal accumulation of fluid in the body. The cause of edema is related to the level of aquaporin (AQP)2 protein expression, which regulates the reabsorption of water in the kidney. Edema is caused by overexpression of the AQP2 protein when the concentration of Na+in the blood increases. The rhizome ofAtractylodes macrocephalahas been used in traditional oriental medicine as a diuretic drug; however, the mechanism responsible for the diuretic effect of the aqueous extract fromA. macrocephalarhizomes (AAMs) has not yet been identified. We examined the effect of the AAM on the regulation of water channels in the mouse inner medullary collecting duct (mIMCD)-3 cells under hypertonic stress. Pretreatment of AAM attenuates a hypertonicity-induced increase in AQP2 expression as well as the trafficking of AQP2 to the apical plasma membrane. Tonicity-responsive enhancer binding protein (TonEBP) is a transcription factor known to play a central role in cellular homeostasis by regulating the expression of some proteins, including AQP2. Western immunoblot analysis demonstrated that the protein and mRNA expression levels of TonEBP also decrease after AAM treatment. These results suggest that the AAM has a diuretic effect by suppressing water reabsorption via the downregulation of the TonEBP-AQP2 signaling pathway.

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Planning to Minimize the Human Muscular Effort during Forceful Human-Robot Collaboration

ACM Transactions on Human-Robot Interaction ◽

10.1145/3481587 ◽

2022 ◽

Vol 11 (1) ◽

pp. 1-27

Author(s):

Luis F. C. Figueredo ◽

Rafael De Castro Aguiar ◽

Lipeng Chen ◽

Thomas C. Richards ◽

Samit Chakrabarty ◽

...

Keyword(s):

Muscular Activity ◽

The Body ◽

Force Output ◽

Content Type ◽

Joint Torques ◽

Shared Object ◽

Muscular Load ◽

Robot Configuration ◽

Human Robot Collaboration ◽

Muscular Effort

This work addresses the problem of planning a robot configuration and grasp to position a shared object during forceful human-robot collaboration, such as a puncturing or a cutting task. Particularly, our goal is to find a robot configuration that positions the jointly manipulated object such that the muscular effort of the human, operating on the same object, is minimized while also ensuring the stability of the interaction for the robot. This raises three challenges. First, we predict the human muscular effort given a human-robot combined kinematic configuration and the interaction forces of a task. To do this, we perform task-space to muscle-space mapping for two different musculoskeletal models of the human arm. Second, we predict the human body kinematic configuration given a robot configuration and the resulting object pose in the workspace. To do this, we assume that the human prefers the body configuration that minimizes the muscular effort. And third, we ensure that, under the forces applied by the human, the robot grasp on the object is stable and the robot joint torques are within limits. Addressing these three challenges, we build a planner that, given a forceful task description, can output the robot grasp on an object and the robot configuration to position the shared object in space. We quantitatively analyze the performance of the planner and the validity of our assumptions. We conduct experiments with human subjects to measure their kinematic configurations, muscular activity, and force output during collaborative puncturing and cutting tasks. The results illustrate the effectiveness of our planner in reducing the human muscular load. For instance, for the puncturing task, our planner is able to reduce muscular load by 69.5\% compared to a user-based selection of object poses.

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