The great indoors
June 20th, 2016
If you’ve ever seen behind-the-scenes footage of animated film or video game productions, you might be familiar with motion capture — the systems used to record movements and facial expressions of the actors and athletes you eventually see come to life on-screen.
At Lily, we don’t use this system to make movies or video games. We use it to collect meticulous data about the Lily Camera’s location in the world — specifically, in this case, the Lily Camera’s whereabouts within our indoor testing facility. This facility, fondly referred to as “The Cage,” allows us to properly validate that our flight software is performing up to our standards.
Nine OptiTrack cameras line the top parameter of The Cage. The cameras are outfitted with IR LEDs, emitting infrared light. These cameras are designed to track the series of small reflective spheres we attach to beta Lily Cameras during indoor testing.
Each OptiTrack camera captures a 2D image of the entire testing space, tracking any surface that’s reflecting IR light. The cameras are calibrated to know where they are in relation to each other, so they are then able to create a 3D map of the Lily Camera’s exact location in space. This map allows us to collect data regarding the attitude controller, position controller, PID tuning, and each of the device’s sensors (Accelerometer, three-axis gyro, magnetometer, barometer, front-facing camera, bottom-facing camera).
But what’s the point of testing the Lily Camera in this obsessively controlled environment if the device should be able to ruggedly endure the messy battle dome of mother nature? How does this system enable better flight control and motor tuning? Solid questions.
Imagine yourself riding a bike. You’re riding along, and suddenly you hear something near your pedals go “click-click-click-clank.” It sounds like it’s coming from your derailleur, but then again it could be the cassette. You’re not sure. It’s anyone’s guess. You have two options. You can hop off the bike, dust everything off, make some minor adjustments, then hop back on and hope for the best. Or, you can pop into your local bike shop for a tune up. You have a seasoned professional take your bike apart piece by piece, isolating the exact location of the issue, then rebuilding it anew.
It’s the same process in The Cage. When a feature is developed, we test in pristine indoor environmental conditions. Once validated there, we integrate the feature into to the full software build, and off it goes into the wild field testing frontier. Testers return from the field at the end of the day with a whole new set of data. We then strip down variables to isolate issues spotted in the field, fine tune, rinse, and repeat.