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Thread: Chasing a LASER pointer

  1. #1
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    Chasing a LASER pointer

    I've been playing off-and-on with using RoboRealm to get a 'bot to chase a LASER pointer.

    It's tougher than it looks at first-blush. Lighting plays a huge part, and it's amazing how much red light there is out there. The pointer I have is [never thought I'd say this] too collimated - the dot is too small.

    I've had limited success in a primitive sort of way. My algorithm for speed/direction control is written in the built-in BASIC interpreter - and it works a lot better turning than going straight, go figger. Just about the time the algorithm is working at the same time the vision system is bounding the pointer, the lighting changes, and I have to start over with the image processing chain.

    I'm too frustrated at the moment to continue debugging it, so I'm posting instead... Normally I wouldn't post a video of something this "unpolished". If I ever get it really working reliably - I'll see about posting some code.

    Windows Media 8, 500kbit/sec, ~5MB download or stream.

    http://www.jlrdesigns.com/robovids/robo-071.wmv

  2. #2

    Re: Chasing a LASER pointer

    Quote Originally Posted by Adrenalynn View Post
    Normally I wouldn't post a video of something this "unpolished". If I ever get it really working reliably - I'll see about posting some code.

    Windows Media 8, 500kbit/sec, ~5MB download or stream.

    http://www.jlrdesigns.com/robovids/robo-071.wmv
    This is still impressive! I think part of the problem might be the contrast between the laser pointer dot and the ground. Try it on a darker floor and see if your tracking doesn't improve.

    8-Dale
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  3. #3
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    Re: Chasing a LASER pointer

    Thanks, Dale!

    The surface in this case is a deliberate choice. I need to optimize to it.

    There are some newer features in the latest roborealm that are documented on the website but not, apparently, in the docs. Filters -> Flatten looks really promising as its a much more advanced averaging than what I've been doing.

    I've made some decent progress. I suspect that if I sleep on it, I'll get something figured out tomorrow. I'm always so impatient and expect my code will just work perfectly the first time. It's probably not all that bad for a first real attempt.

    New video after I have a nap.

    Thanks again!

    --- A

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    Re: Chasing a LASER pointer

    Its been a while since I built a vision system (college in fact!), so I might be off. Have you looked into the types of physical filters that you can put over the camera? I have tried to find filters for red laser pointers, but can't seem to find anything myself <$200.

    What about taping a IR laser next to your visible, and have the robot track the IR laser with a visible cutoff filter on the camera?

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    Re: Chasing a LASER pointer

    thread moved - Brains of my Robot is for SBCs, Laptops, Computers, etc.

    �In the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed�
    - Charles Darwin

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    Re: Chasing a LASER pointer

    Thanks Sienna - I was recommending bandpass filters to someone awhile back - wasn't it you? Sorry to here you didn't find one. They're out there, though!

    Bandpass is one way that might help, but this is NTSC - Never Twice Same Color. IR is crazy noisy, especially in commercial lighting. If this next idea doesn't work out, I'll consider both, though.

    I did wake up with an idea: modulating the laser. If I put a small microprocessor on the laser and pulse the laser in some known fashion, I should be able to junk everything that isn't laser, right?

    -----

    Sorry Alex, I didn't see anyplace fitting better. Machine Vision runs on PCs, and is the robot's "optic nerve" into the PC Brain.

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    Re: Chasing a LASER pointer

    Man, what a difference using a LASER that ... doesn'tsuck makes!

    I have a commercial Hilti laser measuring system. Switching to that instantly resolved my lighting issues. I could just threshold and be done. Very fast processing.

    I'm contemplating taking a hike up to OfficeStaplesDepotMax (tm) and seeing if they have a decently beefy pointer...

    I should probably move this to my blog, huh?

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    Re: Chasing a LASER pointer

    Quote Originally Posted by Adrenalynn View Post
    I did wake up with an idea: modulating the laser. If I put a small microprocessor on the laser and pulse the laser in some known fashion, I should be able to junk everything that isn't laser, right?
    I was thinking the exact same thing, but what worried me was that a camera system at 30Hz might not be able to see a modulation scheme, because its too slow. (don't they usually modulate IR at over 30kHz?)

    I have looked at the 50mW+ lasers on ebay... if you really wanted a powerful one, they aren't that expensive!

  9. #9
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    Re: Chasing a LASER pointer

    29.974ish Hz, as memory serves...

    I could modulate the laser as slow as I wanted, so as long as I kept the max rate in mind, it wouldn't really matter other than being unfortunately slow...

    I did switch to a stronger LASER (Class 4b), but my design requirements spec use in school, so that's just not gonna fly longer term, I'm afraid. I need to get it back down to a Class 2.

    Thanks, Sienna!

  10. #10
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    Re: Chasing a LASER pointer

    Baby steps...

    Forward tracking is working (drive rate was slowed down for debug)

    ~3MB MP4 AVI: http://www.jlrdesigns.com/robovids/laser-forward.avi

    Next up: Reverse. Although it's probably not required since turning works...

    Note: LASER pointer upgraded to the Hilti laser measuring/ranging system. I'll try a new pointer soon, but this does solve 100&#37; of my lighting issues...

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