Big news: we've finally got a version of the Lego UAV that's based on GPS! The previous versions used a compass sensor as a proof of concept, but we've now upgraded it to use a third-party GPS receiver, connecting to the Mindstorms NXT brick by Bluetooth. This allows us to employ proper waypoints and to navigate to specific geographic locations, including returning home. Right now the code is in an early beta, but the key bits work. You can download the RobotC code here.

Special thanks go to a number of people. Dick Swan, the creator of RobotC, was the first to create a Bluetooth interface to a GPS device. Steve Hassenplug created an excellent GPS parser for his Green Monster outdoor wheeled Lego robot and was kind enough to share the code. And Ralph Hempel, the creator of pbLua, helped a lot in the early stages of solving the Bluetooth interface problem. Although we ended up going with RobotC, not Lua, in the end, he showed the way.

Coming up next: I've got to tweak the code to work properly in the air, and film a demonstration using real-time telemetry and aerial video to show how well it follows its waypoints when under autopilot control. And after that? Well, we've got some prototype hardware the promises to remove the mechanical complexity of the Lego-to-control-surfaces problem entirely. It would also allow us to bring the elevator under autopilot control, allowing us to do a proper altitude hold. Finally, there's a possibility that we may be able to also do aircraft stabilization with Mindstorms using inertial sensors, which would allow us to eliminate the FMA Co-Pilot that we're currently using. I can't say more about this yet, because it's using unreleased hardware, but stay tuned.

We've only just begun!

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Comment by roger on February 17, 2008 at 7:22pm

I tried using the beta code (uav2.c) you posted above on my brick. Quick question ... looking at the text of the code and on the fifth line it states

"const tSensors kCompass= (tSensors) S1;"

tried looking at the rest of the code and there's no reference to the compass sensor. So, is the fifth line code an artifact of the compass simulated GPS system you indicated in previous posting? I have no background on C or RobotC for that matter so an innocent question is will deleting the fifth line not affect the working of the code?


3D Robotics
Comment by Chris Anderson on February 17, 2008 at 7:28pm
Yes, that's left over from the previous version and can be safely deleted. Sorry for the mess!
Comment by Laggylarry on February 24, 2009 at 2:38pm
Hi, do you think that you could send me the Green Monster source code by Steve Hassenplug. I am trying to make a GPS robot.
p.s. your guys code is really good.

3D Robotics
Comment by Chris Anderson on February 24, 2009 at 4:27pm
I'm afraid you'll have to get that from Steve. It's not ours to distribute.
Comment by Laggylarry on February 24, 2009 at 4:49pm
fair enough, i tryed emailing him from the contact part of his page a couple of days agao but still have no reply. do you have an email adress that i can reach him at?

3D Robotics
Comment by Chris Anderson on February 24, 2009 at 4:53pm
Yes, but I can't give that out either. Sorry to be unhelpful, and I hope he'll respond to your contact page query.
Comment by Laggylarry on February 24, 2009 at 4:56pm
Not a problem thanks any ways :(
Comment by Steve Hassenplug on February 24, 2009 at 6:27pm
I just replied to your e-mail from last night.



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