Posted by John Gantner on June 10, 2009 at 11:20pm
This post is about a live (simulated) FPV system using Google Earth, relaying data over a cellular GPRS/3G network. A while ago I saw a commercial OSD setup that used Google Earth to simulate an FPV display. Needless to say, I was immediately smitten. However, video TX gear is expensive and a hassle, so Google Earth here serves as a simulated FPV. Hopefully this will eventually mature into a Google Earth HUD (like the Flight Sim easter egg already in it, but real-life!) Comments/Questions/Suggestions welcome. This is just a proof of concept for now, so it is really just an experiment to help me learn KML.
Basically, it is:[Controller]--Serial-->[Bluetooth module]--Bluetooth-->[Cellphone]--GPRS/3G-->[Server]<--GPRS/3G/Wifi/Wired-->[Ground Station]The server, and the roundabout, non-streaming nature of the system, is required because of NATing, and carrier APNs generally not allowing anything but straight HTTP and outgoing connections (and generally being terribly unreliable).So here's some simple PHP scripts. PHP was used because I found a free host that offered it. These have very little error-checking and are generally hacky. There isn't really anything written up about how to use them yet. Caveat emptor.kmlupdate.php - Called by the UAV. Takes any POST/GET data and appends it to a csv file on the server.loadkml.php - Generates a KML file for GE that has 2 NetworkLinks in it. The ground station calls this page once at the beginning of the flight to setup for live telemetry.lightkml.php - This one is called by GE via the KML NetworkLinks that loadkml generated. It dynamically returns (only) the latest data in a 3D point form and in a simulated FPV form. It's called lightkml because it is designed to use only a small amount of bandwidth, useful if the ground station is on costly GPRS/3G. I could really cut it down by building the file locally, but I can't really be bothered to do it right now.heavykml.php - Still working on this one. It has a rollercoaster-like animated FPV tour and 2D/3D line tracks. It returns the entire flight each time it is called, not just the last point, so it is only suitable for post-flight review.I don't actually have the Bluetooth module yet (or the actual controller for that matter, but I do have a program spitting out simulated datapoints for testing), so I won't upload the J2ME stuff until I get a chance to test it. Right now I am only simulating the Bluetooth and the UAV data on a J2ME emulator. Theoretically, it should work on any Bluetooth J2ME phone that properly implements JSR-82 with RFCOMM and has HTTP available.To try it out you can load the scripts somewhere then do something like://Some simulated data stored at "test". Google Earth's camera roll/pitch/yaw is not like a plane. Altitude is absolute.http://127.0.0.1/kml/kmlupdate.php?filename=test&latitude=37.796037&longitude=-122.390736&altitude=200&roll=-40&pitch=82&yaw=178//Generate the KML file. Save this and rename it to a .kmlhttp://127.0.0.1/kml/loadkml.php?filename=test//Start Google Earth and load the "loadkml.kml" file//Select one of the 2 types of views, static view 3D point or animated FPV. The annoying "bouncy" effect on FPV will be removed soon. It will autoupdate every second, so try entering new data in kmlupdate and watch the results. It only displays the last point to (eventually) save on bandwidth. To stop the bouncing or to stop updating uncheck the boxes.Files: phpkml.zip
The concept sounds great. I have many recorded UAV flights that I would love to see from google earths perspective as though I was flying again. To do it real time via cellular uplink would be even better.
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