Auto Pilot

Discussion in 'The Projects Forum' started by circuitbob, May 25, 2012.

  1. circuitbob

    Thread Starter New Member

    Aug 29, 2011
    15
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    Hi, due to disabilities, I’m am having a custom pontoon built. What I would like to do is build an auto pilot system that works like this:

    the pontoon is manually driven from point a to point b
    While this is happening, a GPS must be recording and storing the points
    Now, when I want to get back to point A from B, the GPS must be read and sent to my steering system(can be designed to work with whatever I come up with here or another forum)
    While moving back to point A, the GPS must be monitored to make sure the boat is in correct path.
     
  2. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    Hey circuitbob, you are from lansing huh? I am in lansing now (I work here but live in Vermontville). This sounds very doable.... I have written a few GPS programs and do work with automation a lot (thats what I do for a living.) So if you need some help let me know where you are at and we may be able to get together, (I most likely have everything you would need except for the GPS receiver).
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    Sorry..just had to write this....
    I would call that system the "designated driver" :) I could use that on a Friday night
    I can get to the bar easy..getting home..that's a different story. :)
     
  4. circuitbob

    Thread Starter New Member

    Aug 29, 2011
    15
    0
    Re: Bmorse, I actually live in Dimondale. How would I contact you?
     
  5. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    I will PM you my number....
     
  6. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    sorry to bump this thread mods,
    Did you get my PM CircuitBob? We could start the discussion of what you want done on here to get things started, and so others can maybe benefit from somethings we may come up with for your project.....
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,126
    3,048
    I use my GPS a lot when I boat or run. It usually records a track with good precision, easily within 10 feet or so. But not always, and sometimes tracks are 100 feet off or more.

    I'm suggesting you need to consider how to deal with worst-case gps error, so you don't end up beached. It's much easier if you're on open water and your only precision issue is the last few yards returning to a dock. But on the river where I boat, I'd be quite nervous to hand over control to ANY system. Rivers have other boaters and floating debris to dodge as well, but even without those, the next sand bar or gravel shoal is never far away.
     
  8. BMorse

    Senior Member

    Sep 26, 2009
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    If the system is logging the course, as long as the boat stays in the same position heading back, it should be okay, since the path logged I am sure is free of sandbars, ;)......

    As for obstructions such as other boaters, etc, I already have some ideas in implementing some sort of vision system for obstacle avoidance, etc. Most likely the system will be controlled from a laptop of some sort for map displays etc, so implementing a vision system using a common webcam and utilizing OpenCV libraries should be pretty straightforward...
     
  9. wayneh

    Expert

    Sep 9, 2010
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    But that's my point; the gps precision may vary from usually very good (5-10ft) to occasionally awful (>50ft), and you won't know which it was when the track was laid down, or how it is coming home. Going back to a track point that's 50 ft off could be a bad thing.

    But if you add another layer of security as you've described, that should help a lot.
     
  10. BMorse

    Senior Member

    Sep 26, 2009
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    I have written a few GPS apps before for my own personal use just because the ones available in the market are very inaccurate, but with my program I can get within a couple feet of a targeted destination, and also, locking onto more than 4 satellites and using the coast guard land beacon as another point of reference really helps with the "accuracy".
     
  11. wayneh

    Expert

    Sep 9, 2010
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    I'm skeptical. My GPS receiver uses as many satellites as it can see, is WAAS-enabled, and generally gets me within 2 meters, which is as good as expected for that technology, see below. But the problem is not with when it's working well, it's when it's at its worst. Cloudy day, trees, rain, solar storm, changing ionosphere, whatever.

    Granted, my tracking software is probably smoothing (introducing error into) the raw GPS data. I think running apps do that so that the random bouncing of the signal doesn't get logged as distance you've run. Otherwise I could sit here on my porch and run a nice 10K.

    From the WAAS wiki:

    The WAAS specification requires it to provide a position accuracy of 7.6 metres (25 ft) or better (for both lateral and vertical measurements), at least 95% of the time.[2] Actual performance measurements of the system at specific locations have shown it typically provides better than 1.0 metre (3 ft 3 in) laterally and 1.5 metres (4 ft 11 in) vertically throughout most of the contiguous United States and large parts of Canada and Alaska.[3] With these results, WAAS is capable of achieving the required Category I precision approach accuracy of 16 metres (52 ft) laterally and 4.0 metres (13.1 ft) vertically.[4]
     
  12. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    WAAS is just an augmentation for the GPS specifically tailored for aircraft...... which uses a lot of ground based reference stations...... so I can see if using it on the ground would be inaccurate since it is meant for things that are flying above ground.... :)
     
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