Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Study Some Fishy Behavior to Solve an Animal Locomotion Mystery

06.11.2013
A quirk of nature has long baffled biologists: Why do animals push in directions that don’t point toward their goal, like the side-to-side sashaying of a running lizard or cockroach? An engineer building a robot would likely avoid these movements because they seem wasteful. So why do animals behave this way?

A multi-institutional research team, led by Johns Hopkins engineers, says it has solved this puzzle. In an article published in the Nov. 4-8 online edition of Proceedings of the National Academy of Sciences, the team reported that these extra forces are not wasteful after all: They allow animals to increase both stability and maneuverability, a feat that is often described as impossible in engineering textbooks.

“One of the things they teach you in engineering is that you can’t have both stability and maneuverability at the same time,” said Noah Cowan, a Johns Hopkins associate professor of mechanical engineering who supervised the research. “The Wright Brothers figured this out when they built their early airplanes. They made their planes a little unstable to get the maneuverability they needed.”

When an animal or vehicle is stable, it resists changes in direction. On the other hand, if it is maneuverable, it has the ability to quickly change course. Generally, engineers assume that a system can rely on one property or the other -- but not both. Yet some animals seem to produce an exception to the rule.

“Animals are a lot more clever with their mechanics than we often realize,” Cowan said. “By using just a little extra energy to control the opposing forces they create during those small shifts in direction, animals seem to increase both stability and maneuverability when they swim, run or fly.”

Cowan said this discovery could help engineers simplify and enhance the designs and control systems for small robots that fly, swim or move on mechanical legs.

The solution to the animal movement mystery surfaced when the scientists used slow-motion video to study the fin movements of the tiny glass knifefish. These shy fish, each about 3 inches long, prefer to hide in tubes and other shelters, a behavior that helps them avoid being eaten by predators in the Amazon basin, their natural habitat. In a lab, the team filmed the fish at 100 frames per second to study how they used their fins to hover in these tubes, even when there was a steady flow of water in the fish tank.

“What is immediately obvious in the slow-motion videos is that the fish constantly move their fins to produce opposing forces. One region of their fin pushes water forward, while the other region pushes the water backward,” said Eric Fortune, a professor of biological sciences at the New Jersey Institute of Technology who was a co-author of the PNAS paper. “This arrangement is rather counter-intuitive, like two propellers fighting against each other.”

The research team developed a mathematical model that suggested that this odd arrangement enables the animal to improve both stability and maneuverability. The team then tested the accuracy of its model on a robot that mimicked the fish’s fin movements. This biomimetic robot was developed in the lab of Malcolm MacIver, an associate professor of mechanical and biomedical engineering at Northwestern University and a co-author of the PNAS paper.

“We are far from duplicating the agility of animals with our most advanced robots,” MacIver said. “One exciting implication of this work is that we might be held back in making more agile machines by our assumption that it’s wasteful or useless to have forces in directions other than the one we are trying to move in. It turns out to be key to improved agility and stability.”

The mutually opposing forces that help the knifefish become both stable and maneuverable can also be found in the hovering behavior of hummingbirds and bees, in addition to the glass knifefish examined in this study, said senior author Cowan, who directs the Locomotion in Mechanical and Biological Systems Lab within Johns Hopkins’ Whiting School of Engineering.

“As an engineer, I think about animals as incredible, living robots,” said study’s lead author, Shahin Sefati, a doctoral student advised by Cowan. “It has taken several years of exciting multidisciplinary research during my PhD studies to understand these 'robots' better.”

Other co-authors on the paper were Izaak D. Neveln and James B. Snyder, both Northwestern doctoral students in the Neuroscience and Robotics Laboratory supervised by MacIver; Eatai Roth, a former Johns Hopkins doctoral student now at the University of Washington; and Terence Mitchell; a former Johns Hopkins postdoctoral fellow now at the Campbell University School of Osteopathic Medicine.

This research was supported by National Science Foundation grants 0543985, 0845749 and 0941674, and by Office of Naval Research grant N000140910531.

Phil Sneiderman | Newswise
Further information:
http://www.jhu.edu

Further reports about: Amazon basin Animal PNAS locomotion physical mystery

More articles from Studies and Analyses:

nachricht Amputees can learn to control a robotic arm with their minds
28.11.2017 | University of Chicago Medical Center

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Plasmonic biosensors enable development of new easy-to-use health tests

14.12.2017 | Health and Medicine

New type of smart windows use liquid to switch from clear to reflective

14.12.2017 | Physics and Astronomy

BigH1 -- The key histone for male fertility

14.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>