UAVP-NG: GPS Tracking and KML files

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Hello everybody,

I would like to let you have the latest News: The NG is able to use the GPS for tracking!

After having implemented the GPS NMEA parser some while ago I left the GPS beside because to use GPS for controlling you need a working compass. Since the compass of the current hardware revision is not really useable for that sort of thing, I never got round to use the GPS for something sensible.

Last week I suddently realized that even trough it's not possible to use the GPS for controlling purposes without a compass it surly is possible to use it for tracking! So I started hacking on the GPS tracking feature. I store the GPS positions in RAM and for that I reduce the 3 double precision floats to 6 byte. That way it's easy possible to store 1000 points in the free RAM.

I also implemented a small XML generator which directly outputs KML standard files which can be directly loaded in Google Earth. Furthermore I wrote a new behavior action named gps.track() which takes one parameter telling it to switch it on or off.

Writing a behavior rule to switch on GPS tracking when reachin flightstate FLYING and a second rule to stop GPS tracking when leaving flightstate FLYING took another minute and was a two-liner in the NG console.

The first GPS tracking flight was done on the 11.July. A second GPS tracking flight was done 4 days later:

Wolferl-NG: Amir's maiden flight of his 38cm NG from Amir on Vimeo.



nice job, man. i really should get back to coding stuff for the NG project..

Tobi, you are welcome anytime... :)

Hi Amir,
Have been trying to get you over the mail.I guess you are busy.I have an idea for the real time GPS way point navigation in terms of the hardware.. :)

I left the GPS beside because to use GPS for controlling you need a working compass.

What about starting out in a random direction, and checking the GPS coordinates after like 50 meters? If the GPS is precise enough, you could deduce the angle you have to turn to reach your goal..
This is an oversimplification and just an idea, but still...
In my opinion, starting out in the wrong direction isn't wrong, as long as it's documented.

Really really great job, wish I could fly one of these one day :)

Hi Gabor, Yes, I already pondered this once. One could implemented a airplane-style GPS position hold that way and circle around the waypoint. I never found the time to implement this trough and since the new HW-0.20 now is able to use two different working 3D compasses (the MM3 and the MK3Mag) I don't think we will implement that just now... The real thing is more interesting... ;)



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This page contains a single entry by Amir published on July 17, 2008 10:12 PM.

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