Wednesday, February 22, 2017

2017-02-22: Autonomy Incubator Welcomes Swarm of CICADAs

Danette pulls a Cicada from its crate to show PIs Rania Ghatas, Jim Neilan, and Matt Vaughan.

Four boxes of color-coded CICADA gliders arrived from the Naval Research Laboratory before lunch today, and we were all as excited as you'd expect someone who just received 150 tiny flying robots in the mail to be.

Kyle McQuarry with a fresh-from-the-box yellow CICADA.

These little guys will be dropped en masse from the Hive to gather atmospheric data on the upcoming OWLETS mission. Essentially, the Hive will carry them high into the air at the beginning of the route and release all 150 of them at the designated altitude, and then the CICADAs will autonomously navigate to the end point, collecting air quality data the whole way there.

Before that happens, though, we have to make sure they're all flight-ready and fully functional. That duty falls to PI Matt Vaughan.

"I'm checking to make sure that the GPS is working, that it powers on, that it knows right from left," he said. "We also need to check their pairing mechanism, where if you stack them they go into armed-for-flight mode."

Stacked and armed CICADAs.
One of the coolest features about the CICADA is the way they preserve battery life: they don't arm for flight until they're stacked in pairs, when magnets on the front and back ends of each vehicle align. Once they're armed, they don't switch on and start navigating until they're unpaired by the force of free-falling.

"When they separate from each other as they fall and tumble, they'll realize, 'Oh, I'm falling because I'm not paired anymore,' and then they'll enter spin recovery mode, get a GPS fix, and start gliding towards where the waypoint is," Matt explained.

Separated and ready-to-glide CICADAs.

Once the CICADA reaches its GPS waypoint, it enters a spiral pattern around the point until it hits the ground. All of the navigation happens onboard via a GPS sensor and two servos to adjust the wing flaps; communication with the ground station only involves streaming data and status updates of the sensors.

Ben is actually holding the CICADA right side-up—
they fly with the bulk of their bodies underneath them.

Before we can start dropping CICADAs anywhere, however, Matt must overcome one more logistical hurdle.

"I have to charge all of them," he said. "I need a lot of cables and a lot of chargers."

Note: If you're interested in reading more about CICADAs, here's a NRL press release, an article from AFCEA that I found helpful, and here's an AIAA conference paper from NRL explaining the design evolution. 

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