- Feb 2021
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www.scienceintheclassroom.org www.scienceintheclassroom.org
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We took advantage of the regular and symmetrical shape of the quadruped to illustrate camouflage strategies that can break up recognizable silhouettes
By using a common geometrical shape the authors were able to better camouflage the robot by using the idea that the robot fit in with the normal geometry found in nature. If the robot was designed in a way that caused it to have an abnormal shape it would have a harder time hiding in specific environments where there was more repeated normal patterns.
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Simple image analysis performed on the camouflaged and uncamouflaged robot
Through the different experiments preformed on the robot grayscale thresholding was used as a way of determining which if the specific intensities of the the color layers on the robot matched those of the background. Also infrared thermal imaging was used on the robot to note how color change in the color layers affect the camouflage of the robot in the IR spectrum
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Ecoflex, unlike the materials used in commercially available flexible electronic displays, has a Young’s modulus that is compatible with the flexible bodies
Mechanical Property tests were run for Ecoflex comparing it to polydimethylsiloxane and polycarbonate. Here it was observed that the great elasticity of Ecoflex made it better suited to be used on the robot based on the movement patterns of the robot.
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The translucency of Ecoflex also helped the machines blend in with their surroundings
Previous test were run on Ecoflex and while it was not a translucent as substances such as polycarbonate it showed greater ability to stretch than other competitors which made it ideal for robot.
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The color layers are easily fabricated
Color layers were fabricated using soft lithograpy of Ecoflex in combination with a thin film. They were then coated with a liquid and attached to the robot
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Although there are technologies, such as electrowetting (25) and electrofluidics (26), that use microfluidics to tune color, they rely on electric fields to move fluid and are not immediately compatible with our compressed-air power source.
Electrowetting is a method by which electric fields are used in order to manipulate liquids on the surface of an object. For example, water droplets on the surface of paper can be manipulated in order to create a reflective surface.
Electrofluidics is technique that is a successor to electrowetting. Here liquid dispersion forces are used in order to pull colored oil from a reservoir and into an observable area greatly increasing the ability to see color.
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J. Heikenfeld et al., Nat. Photonics 3, 292 (2009)
This paper details a technique that rivals conventional electrowetting techniques. Here liquid dispersion forces are used in order to pull colored oil out of a reservoir and into an observable area greatly increasing the ability to see color while enhancing contrast.
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R. A. Hayes, B. J. Feenstra, Nature 425, 383 (2003)
This paper describes the process of electrowetting. This process is a way of taking paper and using electric fields to manipulate water droplets that are found on the surface of the paper. In terms of application this paper uses electrowetting as a way of creating a reflective surface that can be altered.
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24. A. Rogalski, Prog. Quantum Electron. 27, 59 (2003).
This paper was published in 2003 and highlighted advances in the field of thermal imaging. Specifically advancements in infrared detection was made. Here the author highlights three new techniques to detecting infrared waves.
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Semiconductor technology has expanded our ability to see into the IR (24), and we explored techniques for camouflage or display in the IR
In 2003 Antoni Rogalski published his work on detectors that can see into the infrared spectrum (IR) here he highlighted three different IR detection mechanism and presented their specific benefits over conventional photon detectors. Here he highlighted resistive bolometers, pyroelectric detectors, and termopile as ways of detecting IR waves. Specifically these techniques make vast improvements in terms of thermal imagining which is used for detecting creatures using camouflage.
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initial approaches to change the color, contrast, pattern, apparent shape, luminescence, and infrared (IR) emission (that is, surface temperature) of soft machines fabricated from elastomers and flexible reinforcing sheets (6–8)
In the past Robert Shephard has been a pathfinder in the field of soft robotics. He has published several articles that introduce the world to what soft robotics are and detail his work building soft robotic machine such as his soft quadrupedal robot. References 6 and 7 detail his previous work more extensively
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These animals typically change color using specialized cells, such as chromatophores or iridophores (4, 9, 10), not simple microchannels
In the past scientist have conducted multiple studies as to how and why different organisms change colors. In nature, organisms rely on specialized cells in order to change color where the author it turning to less biomechanical techniques and using microchannels instead.
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Although specific demonstrations of camouflage vary among species, the strategies used have common themes: background matching, disruptive coloration, and disguise (3, 11, 12)
Past studies have derived that different species may use camouflage for different reasons. However, the techniques that most organism use are widely the same. All organisms will use either background matching, disruptive coloration, or disguise. The author uses these principles for further development for soft robotics. For example, if a doctor was using a soft machine in a surgery and was having a difficult time differentiating the device from its environment. They could utilize the principle of disruptive coloration in order to differentiate the device from a background.
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D. Stuart-Fox, A. Moussalli, Philos. Trans. R. Soc. B Biol. Sci. 364, 463 (2009)
In this piece we start with a review detailing how different studies of color changing organisms has led to what we currently know about camouflage. The paper then goes onto describe how organisms do not only change color based on their background but potentially also the number of predators that are threatening them.
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6. F. Ilievski, A. D. Mazzeo, R. F. Shepherd, X. Chin, G. M. Whitesides, Angew. Chem. Int. Ed. 50, 1890 (2011)
Robert Shephard, who is an author of this work, teamed up with several of his collages in order to help introduce soft robotics to the world. Here he defines what constitutes as soft robotics and how it can be useful to different fields of study.
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