The vast majority of the fancy autonomous flying we've seen from quadrotors has relied on some kind of external localization for position information. Usually it's a motion capture system, sometimes it's GPS, but either way, there's a little bit of cheating involved. This is not to say that we mind cheating, but the problem with cheating is that sometimes you can't cheat, and if you want your quadrotors to do tricks where you don't have access to GPS or the necessary motion capture hardware and software, you're out of luck. Researchers are working hard towards independent autonomy for flying robots, and we've seen some impressive examples of drones that can follow paths and avoid obstacles using only onboard sensing and computing. The University of Pennsylvania has been doing some particularly amazing development in this area, and they've managed to teach a swarm of of a dozen 250g quadrotors to fly in close formation, even though each one is using just one small camera and a simple IMU.

Quadrotors are capable of doing some incredible stunts, like flying through narrow windows and thrown hoops. Usually, when we talk about quadrotors doing stuff like this, we have to point out that there are lots of very complicated and expensive sensors and computers positioned around the room doing all of the hard work, and the quadrotor itself is just following orders. Vijay Kumar's lab at the University of Pennsylvania is often responsible for some of the most spectacular quadrotor stunts, but their latest research is some of the most amazing yet: They've managed to get quadrotors flying through windows using only onboard sensing and computing, meaning that no window is safe from a quadrotor incursion. When you watch quadrotors flying indoors, if you look closely, you'll almost always see a motion-capture system in the background: Arrays of external cameras mounted on the walls that work together to collect very precise positional information hundreds of times every second. With the data that a system like this provides, a computer has no problem issuing very precise commands to a quadrotor flying under remote control to get it to do just about whatever you want.