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Laser Tracker Pan & Tilt — Parallax Forums

Laser Tracker Pan & Tilt

ercoerco Posts: 20,255
edited 2014-10-07 10:11 in Robotics
Four multiplexed lasers and a Hamamatsu S6986 sensor control two servos in a pan & tilt arrangement to actively track a moving Scotchlite reflector. These are the 21-cent lasers from Ebay China. :)

Comments

  • doggiedocdoggiedoc Posts: 2,239
    edited 2014-09-27 04:04
    When can I buy one?
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2014-09-27 06:05
    Alright! I see where this is headed - a laser guided flame thrower!
  • Martin_HMartin_H Posts: 4,051
    edited 2014-09-27 06:36
    The Predator would be proud.

    How did you do the multi plexing of the lasers? If I was doing it with a propeller chip I would have the laser sensor output go into a Propeller pin, and one cog would round robin the lasers, but only enabled them when the laser sensors input was high. With a BS2 I'd use four external AND gates to do the same thing.

    But both of these approaches seem too complicated for your more minimalist and direct style.
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2014-09-27 06:54
    Martin_H wrote: »
    The Predator would be proud.

    How did you do the multi plexing of the lasers? If I was doing it with a propeller chip I would have the laser sensor output go into a Propeller pin, and one cog would round robin the lasers, but only enabled them when the laser sensors input was high. With a BS2 I'd use four external AND gates to do the same thing.

    But both of these approaches seem too complicated for your more minimalist and direct style.

    He is using a PicAxe - http://www.picaxeforum.co.uk/showthread.php?26523-Laser-Tracker-Pan-amp-Tilt&p=271515#post271515
  • PublisonPublison Posts: 12,366
    edited 2014-09-27 06:57
    Well done good sir! I was just going to suggest "I bet he's using a picaxe"

    Any lenses in use?
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-09-27 09:19
    Fantastic erco!

    I love it. Just as I was thinking "is he using four sensors?" you kindly explain how you're using just one. Excellent.
  • ercoerco Posts: 20,255
    edited 2014-09-27 10:01
    Thanks guys. This was a quick impulse project that popped into my head yesterday and I knocked it out in a couple hours. Not a beautiful build at all, I just wanted to git'er done before I slept. Fortunately, it worked the first time, no fuss at all. It helped that the wife and kids are out of town for a week. No interruptions and the whole house to myself.

    The single central laser sensor is surrounded by 4 laser diodes which are all aimed and glued in place to maintain that square pattern. They are fired individually via 2N7000 mosfets in sequence so the sensor "knows" which laser is active, just as Scribbler's single central IR detector works by multiplexing the left and right IR LEDs for object detection.

    Per Martin_H, I keep my hardware and software simple. As Ron divulged (DOH, busted!) I used "another" processor since I was rushed and I had a leftover board built up from a different project. But a BS2 could easily handle this project. In fact the code is tiny, this would also work on a BS1 since it only uses seven I/O pins. One input from the sensor, two servo outputs and four laser outputs. Even with a BS1, there's one extra pin to trigger that flamethrower, Ron... :)

    Edit: No lenses used, Jim.
  • ercoerco Posts: 20,255
    edited 2014-09-30 15:45
    A BS1-IC version of my laser tracker is under construction. I need to right the wrong choice of processor I used. What the heck was I thinking?

    Note to self: order more lasers. Each tracker uses four lasers, 84 cents on the Ebay China market.
  • WhitWhit Posts: 4,191
    edited 2014-09-30 19:18
    Amazing work as usual erco!
  • GrandeNurseGrandeNurse Posts: 110
    edited 2014-10-01 08:00
    Predator (movie) used three, you might be able to save 84 cents.
  • WhitWhit Posts: 4,191
    edited 2014-10-01 19:05
    Predator (movie) used three, you might be able to save 84 cents.

    @GrandeNurse - LOL! - for a newcomer to the forums - you've got erco figured out!

    @erco - he's right...
  • TtailspinTtailspin Posts: 1,326
    edited 2014-10-01 19:38
    Predator (movie) used three, you might be able to save 84 cents.
    @erco, So how is this going to effect the Twins Collage fund?, is there some kind of Pro_rating of the 'Dollar per' bargain purchases? :)
  • ajwardajward Posts: 1,129
    edited 2014-10-01 21:58
    Cool stuff Erco!
  • davejamesdavejames Posts: 4,047
    edited 2014-10-02 09:56
    While this is a very cool project in itself, below is what really amazes me...
    erco wrote: »
    ...and I knocked it out in a couple hours..


    I can't seem to get anything (even simple) done is less than days....errrr, weeks......aw Smile, years!
  • mindrobotsmindrobots Posts: 6,506
    edited 2014-10-02 10:02
    davejames wrote: »
    While this is a very cool project in itself, below is what really amazes me...




    I can't seem to get anything (even simple) done is less than days....errrr, weeks......aw Smile, years!

    My thoughts and feelings exactly......it should be motivational and inspirational to see what he can do in a couple hours. Should be......
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2014-10-02 11:57
    Nice project Erco! Are you going to write this up for one of the magazines? It would be a good topic to cover.

    Robert
  • ercoerco Posts: 20,255
    edited 2014-10-02 17:57
    davejames wrote: »
    While this is a very cool project in itself, below is what really amazes me...

    ...and I knocked it out in a couple hours..

    I can't seem to get anything (even simple) done is less than days....errrr, weeks......aw Smile, years!

    I was a bachelor for three weeks, the wife & kids were in Ohio dealing with her parents' estate. I had the house to myself. Had 7 different projects going. Some home improvement, some honeydos. two paying gigs, and so I didn't feel bad about sneaking in an afternoon for a fun project. Those were productive weeks with no interruption, and I kept the pace up high. Plenty of beer, pizza, and junk food got me thru a SoCal heat wave when I also got caught up on some long overdue miles of running and biking. I'm back on track for 1000 and 5000 miles respectively.

    Family's back now, so my pace in all things will revert to normal. :)
  • davejamesdavejames Posts: 4,047
    edited 2014-10-03 08:24
    erco wrote: »
    ...dealing with her parents' estate.

    ...um, that doesn't sound good.
  • KMyersKMyers Posts: 433
    edited 2014-10-03 09:37
    erco, you da man! Very nice project.
  • ercoerco Posts: 20,255
    edited 2014-10-05 21:14
    Here's my BS-1 based tracker, a neater build than my first one. It actually works better although it only uses ~67% of the BS1's 256-byte memory (~172 bytes). And my quickie code could be crunched even more. That's just a battery box in the base. All electronics are on the moving PCB. Photo attached.
    1024 x 614 - 83K
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2014-10-06 07:08
    2/3rds on a bs1? Who woulda thot? Oh, that's right...erco!
    That is wayyyy cool :thumb:
    -MattG
  • ercoerco Posts: 20,255
    edited 2014-10-06 15:18
    Next steps... I should start a poll to see if people would rather see this tracking device control a flamethrower (yawn) or a taser, demoed on a laser-targeting drone at SXSW: http://www.cnn.com/video/data/2.0/video/tech/2014/03/09/segall-sxsw-stun-drone.cnn.html
  • JonnyMacJonnyMac Posts: 8,992
    edited 2014-10-06 17:19
    I got to see this up close and personal at the Hackaday party -- VERY COOL little board, and very reminiscent of the Predator tracker. Funny, the guy who created the Predator for Stan Winston (Steve Wang) is a friend and client.
  • ercoerco Posts: 20,255
    edited 2014-10-06 17:54
    Thanks Jon, that's high praise and quite a compliment from you. I thought you'd get a kick out of seeing a new BS1 project since you have done so many over the years.

    You can't tell from the video, but it's tracking nearly twice as fast as when you saw it at Hackaday. It was just hours old then (became functional at 3am that day) and since then I got the tracking routine dialed in and sped up.

    I'm making a second BS1 tracker to send to Parallax. Between this laser-seeking unit and the flamethrowing BoeBot I gave Ken, someone in legal is going to have a meltdown. :)
  • Ken GraceyKen Gracey Posts: 7,387
    edited 2014-10-06 20:51
    Great project, erco. Your rate of project completion is currently about 10x mine and Matt's put together! Seeing you do all these neat things inspires us to do the same.
  • ercoerco Posts: 20,255
    edited 2014-10-07 07:53
    Thanks Boss. Now my head is really swelling. Of course my projects are all very simple in nature, 'Cuz I'm a toy guy. If they take more than an hour or two then I made some missteaks along the way :)
  • WhitWhit Posts: 4,191
    edited 2014-10-07 08:57
    @erco - don't be modest!

    @Ken - erco's change of employment has meant an explosion of new ideas!
  • NikosGNikosG Posts: 705
    edited 2014-10-07 10:11
    A M A Z I N G !!!!!!

    Congratulations erco!!!!
    erco wrote: »
    .....I should start a poll to see if people would rather see this tracking device control .....

    My suggestion: Add to your device and a second X-Y base (much more stronger) that will do the same movements as the first base with the laser tracker. Users will be free to put on this second base everything they want (a camera, a rubber gun , a burning laser etc.)

    Edit: You can give the choice the second base to follow the movements of the first base after the user's demand and not every time
  • ercoerco Posts: 20,255
    I just saw this video showing a great application of a laser tracker, teaching a path to a robot. The wheels in my mind are turning!

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