node-ar-drone | js client for controlling Parrot AR Drone | Continous Integration library

There are two ways you could do this.

First, the hard way. The protocol used by node-ar-drone to talk to the AR.Drone doesn't have any way to directly give the drone coordinates to fly to, but you could do the calculations yourself.

1. Enable the drone's magnetometer (see https://github.com/wiseman/webflight-traffic/blob/master/index.js#L19).
2. Calibrate the magnetometer: Command the drone to take off, then do client.calibrate(0) (see https://github.com/felixge/node-ar-drone#clientcalibratedevice_num).
3. Get the drone's magnetic heading from navdata.magneto.heading.fusionUnwrapped.
4. Get the drone's current coordinates from navdata.gps.latitude and navdata.gps.longitude.

5. Compute the desired heading to get from the drone's current position to the desination. There are subtleties to this, but for most applications you can follow the procedure described in http://www.movable-type.co.uk/scripts/latlong.html:

   θ = atan2( sin Δλ ⋅ cos φ2 , cos φ1 ⋅ sin φ2 − sin φ1 ⋅ cos φ2 ⋅ cos Δλ ) where φ1,λ1 is the starting point, and φ2,λ2 is the end point (Δλ is the difference in longitude).

   Since atan2 returns values in the range -π ... +π (that is, -180° ... +180°), to normalise the result to a compass bearing (in the range 0° ... 360°, with −ve values transformed into the range 180° ... 360°), convert to degrees and then use (θ+360) % 360, where % is (floating point) modulo.

6. Figure out if the drone needs to rotate clockwise or counter-clockwise to achieve the desired heading, and call client.clockwise or client.counterClockwise as appropriate.

7. When the drone is facing the correct heading, tell it to move forward with client.front.

Once the drone is headed in the right direction, every time you get new navdata, you should check the current heading, recompute the desired heading, and tell the drone to turn clockwise or counter-clockwise if needed. Once you're within some threshold (5 feet? 50 feet?) of your desired destination, tell the drone to stop with client.stop.

Besides the protocol that node-ar-drone uses, the AR.Drone also supports the MAVLink protocol, used by many hobbyist and commercial drones. That protocol has a way to tell the drone to move directly to specific coordinates. You could use an application like QGroundControl to send the drone to a particular latitude, longitude, or you can use one of the existing MAVLink libraries to send messages to the drone to do the same thing.

DroneKit-Python, for example, is a high-level library that lets you write code like this (taken from this example):