Team Minuteman: Sparkfun AVC ground vehicle--Ardupilot-based


I will be competing in the Sparkfun AVC competition this year using Ardupilot hardware in a ground vehicle. My car is called Minuteman, and works on simple dead reckoning. It uses Ardupilot hardware, with an optical encoder and a gyro as the only sensors. No GPS, no compass, no proximity sensors. Testing has been really simplified by using the ardupilot, because with my 3 channel radio, I can easily switch between auto and manual mode with the push of a button. I can first map-out a course by driving it manually and using my 3rd channel to set waypoints. Then I can put the car in auto mode, and have it re-trace the course. It's pretty simple in theory, but took a lot of fine-tuning to get working.

 

Making this project work with ardupilot required a complete re-purposing of almost everything on the ardupilot. A few modifications were made to the board to facilitate testing, and a fully custom firmware was written. It's hard to say how things will go this weekend at the competition, as I will not have a chance to pre-run the course (until the day of the competition). In near-by parking lots, it performs well. I'm optimistic! 

 

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Comment by Ritchie on April 20, 2011 at 11:28am
Excellent concept and should easily complete the course using the "dummy" run information. Will you be allowed to do a dummy run before your timed entry though?
Comment by Nathan on April 20, 2011 at 11:30am
Yes, there will be time to pre-run the course. I just have to ensure the same initial conditions on each run (position and orientation).
Comment by Paul Mather on April 20, 2011 at 12:48pm
Excellent Nathan, I'll see you there! I'm not competing...just going to meet some of you guys and support my GCS if anyone wants to use it.

Developer
Comment by Randy on April 20, 2011 at 4:50pm

When you say 'optical encoder' what are you referring to?  is that something look at the wheels or looking at the ground?

 

Best of luck this weekend!!

Comment by Nathan on April 20, 2011 at 5:58pm
It looks at a small disk (from an old computer mouse) that is attached to the input shaft of the transmission. It outputs a 0.4V to 4.5V signal, so that it can be read directly by an external interrupt on the ardupilot. That way it just runs in the background.
Comment by Ritchie on April 21, 2011 at 1:48am
May I suggest for next years version a GPS start position would be good. That way you could do your pre-run toggle that it is in GO state and it could find the start automatically.
I am currently trying out something that may help ground and air vehicles alike in sensing but as it's just me it's taking a while.
Comment by Nathan on April 21, 2011 at 2:22pm

Hmm, I have to be pretty accurate with my starting position, but mostly with my starting angle. I don't think GPS would give me the accuracy I need. A good mark on the ground seems to work well. Also my vehicle's navigation system doesn't understand latitude and longitude or any geo-referenced coordinate system. It just knows where it is in relation to where it started. 

 

What is it that you are working on, BTW? 

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