Robot Kinematics

Such a lovely demo:

Comments

  • Fascinating! Complex control of those movements - This would take some time to really get your head around this.
  • Beautiful math behind this!
  • Open source, six axis.

    I bet one of our resident wizards could have this ported to P2 in a weekend :lol:

    https://www.anninrobotics.com/
  • Impossible! :wink:
  • Mickster wrote:
    I bet one of our resident wizards could have this ported to P2 in a weekend
    Why? I think a P1 could do it with power to spare!

    -Phil
  • Mickster wrote:
    I bet one of our resident wizards could have this ported to P2 in a weekend
    Why? I think a P1 could do it with power to spare!

    -Phil

    I have pondered this but as per..

    To represent real world robotics, we need to be talking closed loop servos not steppers.
    Absolute encoders would be ideal but I see incremental being the preferred solution. So we are looking at 18 inputs to cover 6 axes of A, B, I.
    I guess that home sensors could be handled via I²C.
    Motor commands require a minimum of 6 outputs of PWM, assuming that the servo drives can handle anti-phase or the +/- 10v analog filter that you came up with for @JonnyMac. Otherwise we need a further 6 outputs for direction signals.

    Annin have upgraded from open loop to closed loop steppers but without some form of torque limiting of the drives to enable compliance during teach mode, these things will be next to useless.

    The thread over on the P2 section about a good demo for the P2? This could be it.
  • ercoerco Posts: 19,719
    All I need is to see both of those robots racing to operate a labyrinth-style tilt ball maze game using vision to sense the ball location.

    That's ALL I need.

    And this paddle ball game. And this remote control.

    And a BASIC Stamp.

  • @erco - and a pair of optigrab glasses.

    But that's ALL I need.
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  • ercoerco Posts: 19,719
    You got it! Nice job, Boss.

    BTW I can't wait on those jokers above, so I just ordered my own Labyrinth. Can't wait, must automate!
  • [
    erco wrote: »
    I just ordered my own Labyrinth.

    Which one?
    Maybe some of us want to play along.

  • ercoerco Posts: 19,719
    But I'm afraid you'll beat me to it Duane! I'm distracted working on my Corvair for the first time in 20 years! https://www.ebay.com/itm/293414657604

  • 'Always wondered how the turn signal auto-return worked. Thanks for the clear photo!

    Is the stock gas pedal really shaped like a bare foot, or did you add a custom one?

    -Phil
  • ercoerco Posts: 19,719
    It's an add-on. Just as tacky as fuzzy dice. :)

    Unrelated to robots, but nearly as tantalizing. I just got this 1980-vintage Heathkit SB-104A ham rig off Ebay. It's dead, but fixable. Heathkits tend to be serviceable since they are homebuilt, but this will be my most complex Heathkit ever.

    Phipi, pay no attention to the 1941 Phil---co radio in the background. I guess I just like old stuff.

    IMG_1002.JPG


    sb104a.png
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  • ercoerco Posts: 19,719
    edited 2020-06-25 - 04:56:11
    Duane Degn wrote: »
    [
    erco wrote: »
    I just ordered my own Labyrinth.

    Which one?
    Maybe some of us want to play along.

    Mine arrived today, looks good. Bottom panel is just stapled on, should be easy to servo-ize. Comes with two steel ball bearings, could sense those in variety of ways.

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  • ercoerco Posts: 19,719

  • ercoerco Posts: 19,719
    Maybe I got the jump on Duane this time. Here's what I did in a couple hours today.

  • Nicely done!

    Now, why not put an RC receiver in there, and control the axes from one of the transmitter joysticks?

    -Phil
  • ercoerco Posts: 19,719
    Sure could, Tough Guy!

    But I plan to program the servo motions... just hard-coded... to do it automatically. So I can sip Mojitos as the labyrinth plays with itself... wait, that sounds bad...
  • erco wrote:
    But I plan to program the servo motions... just hard-coded... to do it automatically.
    Awesome! Any idea what you're gonna do for position sensing?

    -Phil
  • ercoerco Posts: 19,719
    Thanks for asking, I've thought about this matter in great depth.

    Absolutely NOTHING.

    I'm hoping that brute force and empirical calibration will suffice, in lieu of a plan.
  • ercoerco Posts: 19,719
    (Backup plan: put clear tape over every hole)
  • erco wrote: »
    (Backup plan: put clear tape over every hole)

    LOL
  • You know you want to wire up a grid of hall effect sensors.
  • Maybe glue a 2-axis accelerometer to the underside of the platform, so you can at least calibrate it to level when the program starts?

    I like the clear tape idea! An alternative might be a solenoid under each hole to poke the ball out if it tries to fall through -- kinda like a pinball bumper. :)

    -Phil
  • ercoerco Posts: 19,719
    The time is nigh for Wile E's portable hole.

  • erco wrote: »
    Sure could, Tough Guy!

    But I plan to program the servo motions... just hard-coded... to do it automatically. So I can sip Mojitos as the labyrinth plays with itself... wait, that sounds bad...

    Not at all. I do it all the time....

    Nothing wrong with a few Mohitos. :lol:
  • ercoerco Posts: 19,719
    edited 2020-06-27 - 01:01:12
    This was actually fun to code, even if through brute force testing & calibration. I only got halfway done so far, the cat keeps lounging on the labyrinth. Pic & video attached.



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  • Okay, that's madly impressive! Bang bang control rules!

    -Phil
  • ercoerco Posts: 19,719
    Always wondered how the turn signal auto-return worked.

    Just for you, PhiPi.



  • Thanks, Erco!

    -Phil
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