Flying the Crazyflie with Leap Motion

The first time we saw the video for the Leap Motion we instantly thought “Wow, we have to fly the Crazyflie with this!”. So finally last week a fresh Leap Motion landed on our desk and we went to work. We were really happy to see that there was an SDK for Linux. Leap Motion listened to the community that thought that an early release of the code was better than nothing at all. The API is very nice to work with and you can easily get metrics for you hand (like elevation and roll/pitch). So we created a Leap Motion driver in the joystick layer that replaces the normal input device, and it’s flying! We are going to be honest, at first it wasn’t that fun. It was more the concept that was very exciting. But as we flew more and more it started getting really great! There’s just something magical about it :-)

You fly the Crazyflie using a single hand. Thrust is calculated using the elevation of you hand from the sensor, so holding your hand higher means larger thrust. Pitch/roll is controlled by tilting you hand the same way you want the Crazyflie platform to tilt. So tilting your hand forward tilts the Crazyflie forward. Lastly the yaw is controlled by rotating your hand in the X/Y plane (around the Z-axis). For thrust/pitch/roll the control values are absolute, but for yaw it’s the rate that you control (just like the normal controls in the Crazyflie client).

As a safety mechanism the Crazyflie will only respond if the Leap Motion detects 4 or more fingers. So holding your fist above the sensor does nothing, but the instant you open up your hand you can start to control the Crazyflie.

The code for flying with the Leap Motion is still on a development branch but if you are eager to try it then have a look at the instructions in the hacks section of the wiki for documentation on how to get flying! The plan is to merge the Leap Motion code into the main track once we are finished with the development.