Comments

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  Bot Thoughts February 24, 2013 at 10:52pm

  @Vijay -- I second that recommendation. It's boosted SNR by 10dB on both my SiRFIII and Venus GPSs.

  @KM6VV -- cool! I wanted a tiny form factor that would plug in right next to the sensor with a dedicated ADC and careful PCB layout for better performance (yet to be verified, but I think it'll be good). Prototype Rev0.1 pictured at right.

  @ben -- when your robot is bookin' along at > 25mph trying not to slam into 55 gal barrels and lose the race, ... well... gotta have that obstacle detection :D  But I do have a safety cutover circuit where I have manual control an instant after I turn it on.
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  Bot Thoughts February 24, 2013 at 8:02pm

  I had bad experiences with the MediaTek GPS I had. I love the Venus 638FLPX I am using now. I haven't tried the uBlox yet but have a test one that I keep meaning to play with.
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  Bot Thoughts February 24, 2013 at 8:02pm

  Regarding the IR sensors... I may be able to supply approximate calibration data for both the 150cm and 550cm sensors as I used (or tried to use) both on my rover.

  Also, I am working on an I2C adapter for all Sharp IR rangers if that would be of any use (like, If APM has an I2C port and if the code can support such stuff). The adapter would enable up to 9 sensors on a single I2C bus. It'd either replace the JST connector or would be wired in close to the board. LMK if you want more details.
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  Bot Thoughts February 24, 2013 at 12:13pm

  @ben - I did a lot of testing in empty parking lots and a playground nearby... where are you located? buried under snow? We're getting a pretty heavy snow today but thankfully it melts within a week, usually.
• Dave February 22, 2013 at 11:59am

  another good use for multiple channels is a 4 wheel steering chassis.  (right turn, left turn, right sideways, left sideways) think RC crawler.  right now I use a reversing Y cable to only allow right/left steering but i could think of times when a "slide right/left" would also help.

  Dave P
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  Anthony White February 22, 2013 at 6:26am

  I second Doug's sentiment!
• T3

  healthyfatboy February 16, 2013 at 9:02am

  Try this out first. You'll get three positions out of the two-way switch after this mod. I tried it and it works. It's a little delicate work but it'll be faster than adding an Arduino to it.

  http://traxxas.com/forums/showthread.php?8953226-How-to-Convert-sto...
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  Bot Thoughts February 13, 2013 at 6:55pm

  @KM6VV - are you looking to do the Chibots, RoboGames or another Robomagellan? The RoboGames one says they give you coords with WGM84 (but yeah who knows how accurate the position is, how it was measured, etc) with precision carried out to the thousandths of minutes place.
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  Bot Thoughts February 12, 2013 at 3:37pm

  @KM6VV the main link to read is the oreillynet one. The summary is there are so many sources of error that unless you can do some fancy stuff, two GPS aren't better than one. I confess I don't grok it, but I sorta-kinda get the gist.

  My poise entering the circle is usually within several degrees of the waypoint, at least in practice. On asphalt. But easily within FOV of any normal camera.

  I haven't coded my bot for RoboMagellan but I would do like you said and have a vision system, like CMUcam, provide the angle. That could be fused in with the other sensors, I'm sure.

  Probably good to have a sanity check for expected angle from poise estimate versus what the camera reports to prevent chasing a poodle in an orange sweater :)

  Do the competitors know the exact coords of the cone ahead of time? If so then the cone is essentially a beacon / calibration point all by itself.
• Randy Brazeau February 12, 2013 at 3:06pm

  Could this setup with the GPS be considered as beacons? I was looking at beacons awhile back as a solution for myself. Cell towers but can't get the resolution then perhaps a number of small beacons using frequency, IR for example in my yard.
  Randy