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Title Change: turns out the magic word is "small" — Parallax Forums

Title Change: turns out the magic word is "small"

rjo__rjo__ Posts: 2,114
edited 2016-05-28 22:44 in Robotics
I would rather buy than build:)

I'm looking for something equivalent to a robotic arm but ... really really tiny. And I'm not finding anything.  "micromanipulater" doesn't turn up anything useful... bunch of cell research microscopes stuff. "Micro robotic arm" didn't turn up anything. "Mini robotic arm" turns up units that fit on a desk but not in my hand.

They must exist... where are they?

I've been at it for about an hour and I haven't even found a thesis.

Comments

  • rjo__rjo__ Posts: 2,114
    I'm planning to use visual feedback... so all I am really looking for is smooth action... steppers or servos shouldn't matter... motors should probably be in the base. Even nitinol should work... where are they?
  • Beau SchwabeBeau Schwabe Posts: 6,547
    How small is small?... we have micro CNC machines capable of removing microns at a time, but a CNC machine is probably not what you are after. One of the problems you will be faced with is that the smaller you scale down, what once was seemingly small incremental motions, now become very LARGE motions. A servo will not have the resolution and nitinol will be very slow with a poor feedback loop, even if that closed loop is a visual operator. What we use are stepper motors in a micro stepped mode that can dither about 200 thousand steps per revolution combined with a zero backlash lead screw. Additionally (for the Z axis) we use a linear drive that works like a voice coil... again dithered to provide several thousand micro-steps per cm of travel. In any case, the machines are not small.
  • rjo__rjo__ Posts: 2,114
    The smaller the better. For a start, I was looking for something that would fit in an Altoids tin. Maybe what I should do is look around for an arm that can be made with a laser cutter... and then scale it down... hmmm.
  • rjo__rjo__ Posts: 2,114
    That's the ticket... open STL models all over the place.

    Any takers?
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2016-05-28 14:35
    The mechanics are the easy part -- unless you pay big $$ the motors to work an arm won't fit in an Altoids can.

    I would start with getting a spec for the motors, and work from there. Laser cutting thin plastic isn't too hard. If cut from LD polypropylene, very shallow scoring can create hinges for joints (though this material is better cut with a CNC using a very small bit). And then there's 3D models, but I'd worry about strength.
  • rjo__rjo__ Posts: 2,114
    I think I found what I was looking for... real simple, quick build... just need to figure out moving the
    motors to the base and widgeting a manipulator.

    I'll be back:)
  • ercoerco Posts: 20,254
    Love the "arm in an Altoids tin" idea. I just ordered four 3.7g servos, I may have a go at making a simple 3 dof towers of Hanoi arm. Like I've made before, just scaled down. I'd use servos at the joints, IMO bottom-mounted servos & cables up to joints sounds like a mechanical nightmare.

    http://www.ebay.com/itm/Micro-3-7g-Mini-Servo-for-Control-Aeromodelling-aircraft-flight-direction-KK-/301738380483

  • rjo__rjo__ Posts: 2,114
    And I will be eternally in your debt.

  • rjo__rjo__ Posts: 2,114
    Depends upon how you parse that last message, but you know what I mean:)
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