{"208861":{"#nid":"208861","#data":{"type":"news","title":"Sea Turtles and FlipperBot Show How to Walk on Granular Surfaces like Sand","body":[{"value":"\u003Cp\u003EFor sea turtle hatchlings struggling to reach the ocean, success may depend on having flexible wrists that allow them to move without disturbing too much sand. A similar wrist also helps a robot known as \u201cFlipperBot\u201d move through a test bed, demonstrating how animals and bio-inspired robots can together provide new information on the principles governing locomotion on granular surfaces.\u003C\/p\u003E\u003Cp\u003EBoth the baby turtles and FlipperBot run into trouble under the same conditions: traversing granular media disturbed by previous steps. Information from the robot research helped scientists understand why some of the hatchlings they studied experienced trouble, creating a unique feedback loop from animal to robot \u2013 and back to animal.\u003C\/p\u003E\u003Cp\u003EThe research could help robot designers better understand locomotion on complex surfaces and lead biologists to a clearer picture of how sea turtles and other animals like mudskippers use their flippers. The research could also help explain how animals evolved limbs \u2013 including flippers \u2013 for walking on land.\u003C\/p\u003E\u003Cp\u003EThe research was published April 24 in the journal \u003Cem\u003EBioinspiration \u0026amp; Biomimetics\u003C\/em\u003E. The work was supported by the National Science Foundation, the U.S. Army Research Laboratory\u2019s Micro Autonomous Systems and Technology (MAST) Program, the U.S. Army Research Office, and the Burroughs Wellcome Fund.\u003C\/p\u003E\u003Cp\u003E\u201cWe are looking at different ways that robots can move about on sand,\u201d said \u003Ca href=\u0022https:\/\/www.physics.gatech.edu\/user\/daniel-goldman\u0022\u003EDaniel Goldman\u003C\/a\u003E, an associate professor in the \u003Ca href=\u0022http:\/\/www.physics.gatech.edu\/\u0022\u003ESchool of Physics\u003C\/a\u003E at the Georgia Institute of Technology. \u201cWe wanted to make a systematic study of what makes flippers useful or effective. We\u2019ve learned that the flow of the materials plays a large role in the strategy that can be used by either animals or robots.\u201d\u003C\/p\u003E\u003Cp\u003EThe research began in 2010 with a six-week study of hatchling loggerhead sea turtles emerging at night from nests on Jekyll Island, one of Georgia\u2019s coastal islands. The research was done in collaboration with the Georgia Sea Turtle Center.\u003C\/p\u003E\u003Cp\u003ENicole Mazouchova, then a graduate student in the Georgia Tech \u003Ca href=\u0022http:\/\/www.biology.gatech.edu\/\u0022\u003ESchool of Biology\u003C\/a\u003E, studied the baby turtles using a trackway filled with beach sand and housed in a truck parked near the beach. She recorded kinematic and biomechanical data as the turtles moved in darkness toward an LED light that simulated the moon.\u003C\/p\u003E\u003Cp\u003EMazouchova and Goldman studied data from the 25 hatchlings, and were surprised to learn that they managed to maintain their speed regardless of the surface on which they were running.\u003C\/p\u003E\u003Cp\u003E\u201cOn soft sand, the animals move their limbs in such a way that they don\u2019t create a yielding of the material on which they\u2019re walking,\u201d said Goldman. \u201cThat means the material doesn\u2019t flow around the limbs and they don\u2019t slip. The surprising thing to us was that the turtles had comparable performance when they were running on hard ground or soft sand.\u201d\u003C\/p\u003E\u003Cp\u003EThe key to maintaining performance seemed to be the ability of the hatchlings to control their wrists, allowing them to change how they used their flippers under different sand conditions.\u003C\/p\u003E\u003Cp\u003E\u201cOn hard ground, their wrists locked in place, and they pivoted about a fixed arm,\u201d Goldman explained. \u201cOn soft sand, they put their flippers into the sand and the wrist would bend as they moved forward. We decided to investigate this using a robot model.\u201d\u003C\/p\u003E\u003Cp\u003EThat led to development of FlipperBot, with assistance from Paul Umbanhowar, a research associate professor at Northwestern University. The robot measures about 19 centimeters in length, weighs about 970 grams, and has two flippers driven by servo-motors. Like the turtles, the robot has flexible wrists that allow variations in its movement. To move through a track bed filled with poppy seeds that simulate sand, the robot lifts its flippers up, drops them into the seeds, then moves the flippers backward to propel itself.\u003C\/p\u003E\u003Cp\u003EMazouchova, now a Ph.D. student at Temple University, studied many variations of gait and wrist position and found that the free-moving mechanical wrist also provided an advantage to the robot.\u003C\/p\u003E\u003Cp\u003E\u201cIn the robot, the free wrist does provide some advantage,\u201d said Goldman. \u201cFor the most part, the wrist confers advantage for moving forward without slipping. The wrist flexibility minimizes material yielding, which disturbs less ground. The flexible wrist also allows both the robot and turtles to maintain a high angle of attack for their bodies, which reduces performance-impeding drag from belly friction.\u201d\u003C\/p\u003E\u003Cp\u003EThe researchers also noted that the robot often failed when limbs encountered material that the same limbs had already disturbed. That led them to re-examine the data collected on the hatchling turtles, some of which had also experienced difficulty walking across the soft sand.\u003C\/p\u003E\u003Cp\u003E\u201cWhen we saw the turtles moving poorly, they appeared to be suffering from the same failure mode that we saw in the robot,\u201d Goldman explained. \u201cWhen they interacted with materials that had been previously disturbed, they tended to lose performance.\u201d\u003C\/p\u003E\u003Cp\u003EMazouchova and Goldman then worked with Umbanhowar to model the robot\u2019s performance in an effort to predict how the turtle hatchlings should respond to different conditions. The predictions closely matched what was actually observed, closing the loop between robot and animal.\u003C\/p\u003E\u003Cp\u003E\u201cThe robot study allowed us to test how principles applied to the animals,\u201d Goldman said.\u003C\/p\u003E\u003Cp\u003EWhile the results may not directly improve robot designs, what the researchers learned should contribute to a better understanding of the principles governing movement using flippers. That would be useful to the designers of robots that must swim through water and walk on land.\u003C\/p\u003E\u003Cp\u003E\u201cA multi-modal robot might need to use paddles for swimming in water, but it might also need to walk in an effective way on the beach,\u201d Goldman said. \u201cThis work can provide fundamental information on what makes flippers good or bad. This information could give robot designers clues to appendage designs and control techniques for robots moving in these environments.\u201d\u003C\/p\u003E\u003Cp\u003EThe research could ultimately provide clues to how turtles evolved to walk on land with appendages designed for swimming.\u003C\/p\u003E\u003Cp\u003E\u201cTo understand the mechanics of how the first terrestrial animals moved, you have to understand how their flipper-like limbs interacted with complex, yielding substrates like mud flats,\u201d said Goldman. \u201cWe don\u2019t have solid results on the evolutionary questions yet, but this certainly points to a way that we could address these issues.\u201d\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThis research has been supported by the National Science Foundation under grant CMMI-0825480 and the Physics of Living Systems PoLS program, the U.S. Army Research Laboratory\u2019s (ARL) Micro Autonomous Systems and Technology (MAST) Program under cooperative agreement W911NF-08-2-0004, the U.S. Army Research Office (ARO) and the Burroughs Wellcome Fund Career Award. Any conclusions are those of the authors and do not necessarily represent the official views of the NSF, ARL or ARO.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECITATION\u003C\/strong\u003E: Nicole Mazouchova, Paul B. Umbanhowar and Daniel I. Goldman, \u201cFlipper-driven terrestrial locomotion of a sea turtle-inspired robot, (Bioinspiration \u0026amp; Biomimetics, 2013).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EResearch News\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E177 North Avenue\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia\u0026nbsp; 30332-0181\u0026nbsp; USA\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EMedia Relations Contact\u003C\/strong\u003E: John Toon (404-894-6986)(\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003Cbr \/\u003E\u003Cbr \/\u003E\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EBased on a study of both hatchling sea turtles and \u0022FlipperBot\u0022 -- a robot with flippers -- researchers have learned principles for how both robots and turtles move on granular surfaces such as sand.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Researchers have learned principles for how both robots and turtles move on granular surfaces."}],"uid":"27303","created_gmt":"2013-04-23 16:52:25","changed_gmt":"2016-10-08 03:14:08","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2013-04-23T00:00:00-04:00","iso_date":"2013-04-23T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"208811":{"id":"208811","type":"image","title":"FlipperBot testing4","body":null,"created":"1449180001","gmt_created":"2015-12-03 22:00:01","changed":"1475894869","gmt_changed":"2016-10-08 02:47:49","alt":"FlipperBot testing4","file":{"fid":"196827","name":"flipper-bot136.jpg","image_path":"\/sites\/default\/files\/images\/flipper-bot136_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/flipper-bot136_0.jpg","mime":"image\/jpeg","size":2321339,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/flipper-bot136_0.jpg?itok=BZr2RJM8"}},"208801":{"id":"208801","type":"image","title":"FlipperBot testing3","body":null,"created":"1449180001","gmt_created":"2015-12-03 22:00:01","changed":"1475894869","gmt_changed":"2016-10-08 02:47:49","alt":"FlipperBot testing3","file":{"fid":"196826","name":"flipper-bot80.jpg","image_path":"\/sites\/default\/files\/images\/flipper-bot80_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/flipper-bot80_0.jpg","mime":"image\/jpeg","size":1837999,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/flipper-bot80_0.jpg?itok=GfB0Vk-n"}},"208791":{"id":"208791","type":"image","title":"FlipperBot testing2","body":null,"created":"1449180001","gmt_created":"2015-12-03 22:00:01","changed":"1475894866","gmt_changed":"2016-10-08 02:47:46","alt":"FlipperBot testing2","file":{"fid":"196825","name":"flipper-bot66.jpg","image_path":"\/sites\/default\/files\/images\/flipper-bot66_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/flipper-bot66_0.jpg","mime":"image\/jpeg","size":1829132,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/flipper-bot66_0.jpg?itok=xe80mYl0"}},"208821":{"id":"208821","type":"image","title":"FlipperBot testing5","body":null,"created":"1449180001","gmt_created":"2015-12-03 22:00:01","changed":"1475894869","gmt_changed":"2016-10-08 02:47:49","alt":"FlipperBot testing5","file":{"fid":"196828","name":"flipper-bot218.jpg","image_path":"\/sites\/default\/files\/images\/flipper-bot218_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/flipper-bot218_0.jpg","mime":"image\/jpeg","size":3108178,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/flipper-bot218_0.jpg?itok=wPjnjyU_"}},"208781":{"id":"208781","type":"image","title":"FlipperBot testing","body":null,"created":"1449180001","gmt_created":"2015-12-03 22:00:01","changed":"1475894866","gmt_changed":"2016-10-08 02:47:46","alt":"FlipperBot testing","file":{"fid":"196824","name":"flipper-bot48.jpg","image_path":"\/sites\/default\/files\/images\/flipper-bot48_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/flipper-bot48_0.jpg","mime":"image\/jpeg","size":1729881,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/flipper-bot48_0.jpg?itok=sFKFcg7Z"}},"208831":{"id":"208831","type":"image","title":"Sea turtle","body":null,"created":"1449180001","gmt_created":"2015-12-03 22:00:01","changed":"1475894869","gmt_changed":"2016-10-08 02:47:49","alt":"Sea turtle","file":{"fid":"196829","name":"sea-turtle3801.jpg","image_path":"\/sites\/default\/files\/images\/sea-turtle3801_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/sea-turtle3801_0.jpg","mime":"image\/jpeg","size":2531103,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/sea-turtle3801_0.jpg?itok=JNSemOvx"}}},"media_ids":["208811","208801","208791","208821","208781","208831"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"150","name":"Physics and Physical Sciences"},{"id":"152","name":"Robotics"}],"keywords":[{"id":"59331","name":"bio-inspired"},{"id":"47881","name":"Dan Goldman"},{"id":"64831","name":"flipper"},{"id":"64821","name":"FlipperBot"},{"id":"1357","name":"granular"},{"id":"1356","name":"robot"},{"id":"166937","name":"School of Physics"},{"id":"169569","name":"sea turtle"}],"core_research_areas":[{"id":"39481","name":"National Security"},{"id":"39521","name":"Robotics"}],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJohn Toon\u003C\/p\u003E\u003Cp\u003EResearch News\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E(404) 894-6986\u003C\/p\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}