Inside the netted flight test facility at UNLV, two unmanned aerial vehicles (UAVs) glide effortlessly around each other in what appears to be an ethereal dance.
But this isn’t just for show. The UAVs are performing an important function: remotely detecting and identifying radioactive materials on the ground. Their closely coordinated movements prevent them from crashing into one another and ensure they optimally cover the area they’re flying over.
Mechanical engineering professors Alexander Barzilov and Woosoon Yim developed these drones with radiation detection and navigation capabilities so they could carry out dynamically tracked radiation measurements where terrestrial (ground) robot deployment might not be possible—for example, in areas where there is considerable debris, steep downgrades, or deep water. Mechanical engineering doctoral student Jameson Lee, who specializes in dynamics and controls, has also been working with Yim and Barzilov on the project.
In the wake of nuclear accidents and natural disasters such as Fukushima and Hurricane Harvey, researchers like Barzilov, Yim, and Lee have increasingly turned their attention to the role robots can play in assisting emergency response teams with damage inspection, chemical detection, and even search-and-rescue efforts.
“With the ability to monitor over large areas, UAVs can effectively enhance the situational awareness capabilities of first responders,” Yim said.
“For this test, our UAVs are set up with sensors to detect radiation,” Barzilov added. “However, they could just as easily be equipped with chemical sensors, thermal imaging cameras—whatever type of sensor the situation calls for.”
Taking to the Sky
The use of drones by hobbyists and some professionals (such as photographers) has proliferated over the past few years. In general, what they fly are remote-controlled UAVs. A “pilot” controls the movements of the vehicle with a stick and rudder. To a lesser extent, some may use vehicles which are preprogrammed to fly a certain route, adding a layer of automation.
In contrast, unmanned aerial systems (UAS) like Yim and Barzilov’s encompass an entire suite of resources that work together, including the UAV, a ground-based controller, and the system of communications connecting the two. The researchers’ system also incorporates adaptive technology, meaning the UAVs have been programmed to identify different situations and respond accordingly. They can also automatically sense, detect, and avoid fixed obstacles while in flight—including moving ones like birds and other UAVs.
On a rooftop at UNLV, a graduate student sits at the control computer monitoring two UAVs as they run through their motions. The small net-enclosed space limits the number of UAVs that can be flown at one time. With a 4.5-foot diameter, these are not small machines, but they appear to glide effortlessly all the same.
When out in the field, the number of UAVs would increased substantially and be referred to as a “swarm.” By working in cooperative swarms, UAVs can carry out and accomplish complex missions that a single drone couldn’t easily do on its own. They can be programmed to move together or perform individual missions, carrying out their own defined task but always remaining in constant contact with each other and/or the home base to meet project goals.
In short, they collaborate to get the job done.
And since battery life and payload weight pose the two biggest challenges for UAVs, working with multiple units is not only more efficient; it also provides more accurate and comprehensive data. Unmanned ground vehicles (UGVs) can also complement the effort since one of the team’s large UAVs can only be airborne for approximately 30 minutes, whereas the battery of a UGV might last for hours. Collaborative operation of UAVs with UGVs can provide the best of both worlds, in some cases.
Plug and Play
Surprisingly, Barzilov and Yim’s project—which was supported by $893,698 in funding from Savannah River Nuclear Solutions—originally started with the task of developing interchangeable plug-and-play components for UAVs with mobile manipulation capabilities. The plug-and-play functionality of on-board sensors allows for “hot plugging,” the ability to add and remove devices (in this case, sensors) to a computer system while the computer is running and do so in a way the operating system automatically recognizes.
“It’s basically a USB-based device that anyone can use,” Barzilov said.
Plug-and-play components enable those in the field to quickly and easily swap out sensors, which becomes extremely helpful in situations where users on the ground may be first responders or experts in hazardous materials but may not know much about computer software and hardware.
Sensors can include chemical detectors, radiation detectors, and infrared cameras. The UAVs are even equipped with an automated arm that can either pick up samples and bring them back to home base or deploy sensor packages in the field.
With the radiation detection sensor Barzilov and Yim have equipped their UAVs with, the swarm can distinguish between neutron and photon radiation signatures based on signal parameters. A team-developed mapping algorithm helps create visual maps of radiation levels and hone in on the source of a leak or spill.
The team has tested its approach via a source-seeking experiment using a simulated light source, but the real test will be when they get a chance to use their UAVs and sensors in a real-world scenario. Considering Nevada’s history in the nation’s nuclear testing program, there are ample opportunities right here.
There are concerns regarding the feasibility of using robots—whether aerial or terrestrial—for prolonged periods of time in radiation-contaminated areas. High levels of radiation can cause hardware and software to malfunction, and if the radiation is strong enough, it would be almost impossible to equip a UAV with the amount of shielding necessary to protect it without adding too much weight. But it’s certainly a better alternative than jeopardizing the health of humans who might be involved in detecting such materials.
“Our systems and sensors need to be built economically, with the acceptance that we may only get a certain amount of use from them, and then they must be replaced,” Barzilov said. “In a sense, they’re designed to be disposable.”
Although their current research is focused on radiation mapping, Barzilov and Yim envision that the team’s UAV technology could easily make its way into the commercial sector, given its plug-and-play nature. In addition to disaster relief operations, UAVs equipped with various sensors can be used for routine maintenance checks and inspections around nuclear reactor sites, chemical plants, power lines, and bridges. They can help create maps for geographic regions too difficult for humans to access and monitor government land and wildlife as well.
Of course, not every company that could utilize the technology would be able to employ an Federal Aviation Administration-licensed drone pilot, but Barzilov and Yim’s technology could open up opportunities for new companies specializing in UAVs to form and provide such services—an interesting diversification prospect for Nevada’s economy.
About the Artist
Name: Samantha Meredith
Colleges: Honors and Fine Arts
Major: Graphic Design
Specialties: Drawing, painting, and graphic design
Artistic philosophy: “I’m currently working as a designer for a custom T-shirt design company in Las Vegas and enjoy listening to clients’ ideas to create things they can wear. Whether it’s a sketch, painting, design, or illustration, my work is often colorful and aims to make people happy.”
Contact: To collaborate on a project, email Meredith.