The day we crashed the drone
|April 4, 2011||Posted by Michael under Drone, Issues, Testing||
Sometimes, tragic accidents just happen. Well, we were not exactly surprised by the one that affected us last week, when we damaged our AR.Drone so bad it couldn’t fly anymore, since we played with fire. Or rather with wind, to be precise. Besides, when you do numerous experiments with a really light device that can fly really high in the sky, you have to expect to perform some repairing, sooner or later.
Events were as follows. So far, our UAV had only been flying indoors, and we really wanted to try it outside, to watch its behavior in a different setting, to test the wireless range, its reactivity to navigation commands, its speed, its ability to hover despite the wind… We therefore took a laptop, and Xbox 360 controller and our drone in the courtyard next to our building, and started our first outdoor flights.
In spite of an overall mild weather, there was some wind regularly blowing and disturbing from time to time our controls. But the quadricopter proved to be quite steady on the whole and able to respond well, even while being 30 meters away from us. Except with sudden gusts of wind and an obstacle nearby. We crashed it a few times: a window and a vertical pole were its very first close encounters. Those happened however at heights of no more than 2-3 meters, and did not really damage the drone; its security system is indeed really efficient when it comes to shut down the rotors as soon as one of them is blocked. The last accident happened a little higher, around 5 meters; the AR.Drone then immediately stop to start its emergency fall and proceeded to a harsh landing on the concrete ground, using one of its rotors as a shock absorber. Not the best scenario.
As a result, a gear connected to one of the four motors was destroyed, and, worse, the central cross that hold the whole body together was broken at one of four parts. It was still possible to start the drone, but after around two seconds of initiating the rotors – the four of them were still working once the faulty gear removed – its internal sensors detected a problem and it automatically shut down (most probably because one motor wasn’t loaded enough).
The good thing with this accident is that we learned quite a lot on the drone itself, since we had to open it completely to perform the “surgery”. We have seen that it is highly modular, and its functions are well split into distinct parts: propellers, gears, shafts, motors, central cross, motherboard, navigation board, horizontal camera, hull, and so on. Replacement parts can be ordered and video for each kind of fixation are shown on Parrot official website, so the repairing is easily made, whatever the problem is. It is even possible to rebuild a new drone only thanks to replacement parts.
Even if we had to wait ten days to get the replacement parts, the good news are that our drone was then fully functional again. We then took the opportunity to make a video – see below – of us controlling the drone with a Xbox 360 controller linked to a PC which is connected to the drone’s hotspot (WD ARDrone and Xpadder were running on the laptop to enable this kind of flight). Watch how steady it is, and the accuracy provided with the gamepad.