\u201cWe want to help people who study wildlife better track small animals that have been tagged with tiny tracking devices, and we want other labs to take what we\u2019ve learned and improve on it so that biologists have cost-effective tools that best suit their needs,\u201d <\/strong>Shafer said.<\/p>\n\n\n\n Rising\nabove the ground noise<\/strong><\/p>\n\n\n\n For more\nthan 50 years, scientists studying small birds and animals\u2014such as bats, mice\nand lizards\u2014have used a tried-and-true tagging technology that uses very high\nfrequency (VHF) radio beacons to track them. These tags are lightweight,\naffordable and easy to deploy in the field. Nevertheless, the data collected\nhas been sparse because detecting the transmissions and determining exactly\nwhere the signals are coming from are arduous tasks. <\/p>\n\n\n\n After tagging\nand releasing an animal, a field tracker might spend hours or even days combing\nan area for transmissions by using a hand-held or pole-mounted antenna to pick\nup signals, attempting to triangulate the subject\u2019s location. Time is the enemy\nin this research. The tag can come loose or be damaged, and even if it remains\nstable and secure, the battery eventually dies. That means finding and\nrecording the transmissions within a short period is vital. Using UAVs to\nelevate antennas is one way to make tracking more manageable.<\/p>\n\n\n\n \u201cThe\nfundamental idea was to get off the ground,\u201d Shafer said. \u201cWildlife scientists\nhave told me that if they had a 400-foot pole to mount an antenna on, locating\nthe transmissions would be easier. The higher the antenna is from the ground,\nthe better it can pick up distant transmissions because there isn\u2019t as much\nground interference between the antenna and the tag.\u201d<\/p>\n\n\n\n Students design first-generation prototype device<\/strong> <\/p>\n\n\n\n Mechanical\nengineering students in Shafer\u2019s Dynamic and Active\nSystems Lab<\/a> designed the first-generation prototype UAV-mounted antenna to\nhelp scientists home in on transmissions. Unlike a pole, the drone is far more\nagile because it can spin and travel up to 1.5 kilometers.<\/p>\n\n\n\n \u201cWe know\nthat once the antenna is in the air, it can hear the tags\u2019 transmissions much farther\naway than a tracker on the ground can,\u201d Shafer said. \u201cThink of it as a radio\nvacuum cleaner. As it gains altitude, it sucks up all the radio data. For\nexample, we could have it fly a kilometer transect off the road, and when it\ncomes back, we can replay that audio to see whether we hear the tag.\u201d <\/p>\n\n\n\n At this\npoint, detecting the signal is entirely manual. Trackers still use headphones\nand hand-held devices to pick up the signal, but now they can send a UAV to\nfind out approximately where the signal is coming from. In future iterations of\nthe device, Shafer plans to improve signal detection capabilities.<\/p>\n\n\n\n \u201cWe want\nto make improvements to our detection algorithms to make that process easier.\nThat\u2019s something we will pursue in the near future,\u201d he said.<\/p>\n\n\n\n The\nvehicle is fairly large (about 40 inches across and 14 inches tall) because\nShafer said he asked his students to overdesign the first-generation system.<\/p>\n\n\n\n \u201cI told\nthem to overbuild it so that we could pick and choose the parts we want without\nworrying about payload. Most drones aren\u2019t designed to carry much weight, so if\na payload is added, there\u2019s a real drop in flight time. We also built it with\nredundancies so if one motor fails, the vehicle won\u2019t fall out of the sky.\u201d<\/p>\n\n\n\n Providing\nthe know-how to a broad community<\/strong><\/p>\n\n\n\n As part of\nthe NSF grant requirements, Shafer and his team are sharing how they created\nthe device and what they have learned. In the published paper, Shafer, Flikkema\nand graduate students Gabriel Vega<\/strong>\nand Kellan Rothfus<\/strong> provide\ninstructions and a list of the exact materials they used, such as the model of motors,\nthe software they developed and all the other hardware specifications. The team\nalso shared the information on a new website<\/a>.\n<\/p>\n\n\n\n By sharing\nexactly how they constructed their device, Shafer and his team hope that other\nlabs and life scientists will adapt the technology to meet a suite of research\nneeds. <\/p>\n\n\n\n \u201cIf\nscientists are looking for a really small animal on the ground, the antenna can\nbe configured straight down, but if they are looking for a songbird in a tree,\nobviously, the antenna should scan outward,\u201d Shafer said. \u201cThere\u2019s a learning\ncurve, and the users will need to use what they know about animal behavior as\nthey configure the device to work best for them. They will need to experiment\nwith it.\u201d<\/p>\n\n\n\n Shafer joined the faculty of NAU\u2019S Department of Mechanical Engineering<\/a> in 2013. His research interests include unmanned aerial robotic systems, advanced actuation technologies, small scale energy harvesting and bio-inspired engineering systems. <\/p>\n\n\n\n Photo credit: Jose Gabriel Martinez-Fonseca and NAU\u2019s Dynamic and Active Systems Lab<\/em><\/p>\n\n\n\n
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