Tuesday, September 20, 2011

My new GPS unit...

In addition to playing with LEGO robots, I've been a keen geocacher for over four years. (In case you don't know, geocaching is a GPS-based treasure hunting game/sport/hobby/obsession.) As you might expect, there's always some discussion about the various pros & cons of the various GPS units that are available. With the advent of GPS-enabled smartphones, much of the discussion has been about how these compare with "real" GPS receivers (GPSr).

My first GPS unit, and one that I still use when I want a "real" GPSr, is a Garmin etrex Vista Cx, but these days I rarely cache without my iPhone 3GS (I mainly use the Geosphere app). Typically I go caching with both of these, but now I will have a third option...

This is a LEGO Mindstorms NXT with a Dexter Industries dGPS sensor. There are some guides for using this sensor with NXT-G, but I'm keen to see what I can do with LabVIEW for LEGO Mindstorms (LVLM). As a start, I downloaded the blocks for LVLM, wrote a quick datalogging program, and then went for my usual jog. When I came back home, I imported the data (with a little tweaking) in Google Earth. Unfortunately, I forgot to disable the sleep setting on my NXT brick, so I only got the first 10 minutes. Even so, the yellow line below gives a good indication of what the sensor is capable of doing...


I started on the eastern side of the map, and jogged anticlockwise around the hill. I set the NXT to collect the data every 10 seconds, and I'm impressed with how smooth the results were, over all. The start of the trip is a bit off, but this would be due to me hopping out of the car, and starting the journey without giving the dGPS a chance to settle down. The "wiggle" towards the ends of the log is no worse than what I get on my "real" GPSr from time to time on the same track.

Next, I'm going to do a side-by-side comparison of logging a journey on both my NXT and my Garmin, and then I've got to find a cache using only my new GPS unit!!

16 comments:

  1. Would you be so kind to make your program available please?

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  2. Yes, I'll certainly make my program available - but I would like to tidy it up a bit first...

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  3. My programming skills are lacking but my desire to try this out is not. I have just ordered the dGPS unit from Amazon and should have it here in a few days time.

    Thank you.

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  4. Okay ... next stop, an all-terrain lego robot that will "follow the arrow" to a cache all by itself. Now THAT would be awesome.

    (Especially if it can solve puzzle caches!)

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  5. My plan is to attach the NXT with dGPS to the LEGO Unimog 8110.

    See what this 17yr old girl did just days after it was released.
    http://thenxtstep.blogspot.com/2011/08/unimog-nxtification-by-anika.html

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  6. johnrichey - Nice idea. Yes, that is a cool video!

    helen - That's the whole point of a GPS robotics receiver (GPSrr? - could be handy on 'talk like a pirate' day!), isn't it? Not sure about the puzzle solving, but I've got some ideas for the "arrow".

    Dexter - You're welcome! I'm also looking forward to getting those NXTBee's talking to each other in LVLM, but there's plenty left to do with the dGPS first.

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  7. dGPS arrived today. What is the first thing I can do to test that it's working please?

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  8. Not sure how to add a photo, but here is a link to Facebook.

    https://www.facebook.com/photo.php?fbid=10150386355740242&set=a.51945500241.77535.751565241&type=1&theater

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  9. FB isn't showing me that photo for some reason, sorry. As far as support goes, I haven't played with the dGPS in NXT-G yet - only LabVIEW for LEGO MINDSTORMS. I've tidied up my simple data logging program though and intend to write a post about it (including at the very least a screenshot of it) by mid-next week. In the mean time, we've got two big days of RoboCup Junior Australia (www.robocupjunior.org.au) this weekend!

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  10. https://picasaweb.google.com/112041732523333870347/LEGOUnimog#5655786485839255394

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  11. So I wrote my first NXT program tonight using the Google Earth example from the Dexter website but seem to be having an issue with the getting the output file written to the NXT's memory. I must have the data access block incorrectly programmed. Any help would be appreciated. I posted my program here - http://www.johnrichey.com/Google.zip.

    Thanks, jMr
    p.s. HelloWorld example program runs fine - confirmation the dGPS is working. ;-)

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  12. Never mind previous post - found how to get the txt files from the NXT now. Was not selecting "other" in the memory.

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  13. I've uploaded a tidied up version of my LVLM data logging program here... https://sites.google.com/site/robtorok/

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  14. This is really easy to use. Thank you very much. Truck Tracking

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