Friday, July 10, 2015

2015-07-10: Autonomy Incubator Hatches Flock of Micro UAVs

Robotics engineers at institutions all over the globe have begun using very small UAVs for autonomy research this year, from the Technical University of Munich to MIT to USC (the one in California, not the Gamecocks).  Called either "micro" or "nano" UAVs, these tiny machines can fit in an outstretched hand and can be used to support much of the same research as full-size UAVs.  One Master's student in Germany even used one to do research on one of our specialties, visual odometry.

So popular are micro UAVs in the research community, and so intriguing are their possibilities, that Autonomy Incubator (AI) intern Gil Montague has chosen them for the focus of a new collaboration between himself and the coordinated flight trajectory research of interns Javier Navarro and Bilal Mehdi.

Part of what makes micro UAVs so intetesting to work with is the challenges their minuscule surface area presents.

"How do things change when you don't have as much real estate?" Gil said of the main question driving micro UAV research. "While these are fun, they're being used as real research vehicles."

For their spartan cargo capacity, however, they also bring in a few distinct advantages for coordinated flight research: because they're so small, hundreds of them could fly simultaneously in our indoor operational area. The possibilities are astonishing; imagine a demo with an entire fleet of miniature UAVs maneuvering together in a flock or simulating a fleet of different types of aircraft in our National Airspace System (NAS).

Gil's first goal after integrating the micro UAVs into the AI framework is to design a physical demonstration of a simulation called the Pursuit Domain, in which four "predator" entities try to autonomously find and surround the "prey."

"The hardware platform [of a UAV demonstration] is to show in the physical world the capabilities being developed in the simulated world," he said.  So far, the only demo of that kind is robot soccer.  Peter Stone, a professor at the University of Texas and Gil's "favorite person," gave a TedxYouth talk about how using robots to play soccer allowed him to explore machine learning and "ad hoc teamwork." (Here's his paper, if you'd rather read.)

Just like Dr. Stone used robot soccer to further machine learning research, Gil wants to use a live, physical version of the Pursuit Domain. There are a number of ways to run the Pursuit Domain—letting the predators communicate, making them work independently, adjusting how much the prey can move at one time—which makes it an excellent avenue for research as well as a compelling, entertaining demo.

"You can imagine a demo of these [micro UAVs] trying to corner a ... drone," Gil said.

The AI currently has a fleet of eleven micro UAVs, all Crazyflie 2.0TM drones made by Bitcraze.  In order to both shield the tiny props and provide a place to mount fiducials, intern Josh Eddy designed and 3D printed protective bumpers that can be snapped onto the vehicle body without the use of tools.

Because we have so many of them, Gil also plans to explore flocking behaviors with the micro UAVs.  Think of how starlings can fly in massive clouds together, instinctively staying close to each other while staying away from obstacles and predators. Now, imagine replacing the birds with tiny robots, and replicating the birds' natural behavior through autonomous, agile coordinated flight. Because the Crazyflies are so small, Gil says, we could conceivably implement a flocking demo inside Building 1222, in addition to the Pursuit Domain demo.

Besides carrying on the AI's legacy of showstopping demos, the micro UAVS also show promise in the practical applications we're focused on, specifically scientific research and search-and-rescue  implementations. Gil used the example of a building on fire—instead of immediately sending in firefighters to manually search every single room for people, someone on the squad could release a fleet of ten or so micro UAVs with cameras to do a wide-range primary search, saving time and, potentially, lives. And, because they are so affordable, they can be left behind if the situation becomes too dangerous to collect them.

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