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Re: [SeattleRobotics] Johnny5 head control

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  • Claus
    What about electric pistons?
    Message 1 of 15 , Mar 1, 2002
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      What about electric pistons?


      Mensaje citado por: Kenneth Maxon <kmaxon@...>:

      > Quite often PWM is used to drive a solenoid to a particular extension.
      > This
      > can be coupled with closed loop feedback, however with some careful
      > measurements open loop control will work.
      >
      > -Kenneth
      > (Unit 3\'s in trouble and it\'s scared out of its wits) -Geddy Lee
      > ----- Original Message -----
      > From: <BusterBot@...>
      > To: <SeattleRobotics@yahoogroups.com>
      > Sent: Wednesday, February 27, 2002 2:54 PM
      > Subject: [SeattleRobotics] Johnny5 head control
      >
      >
      > > What is the two items on each side of Johnny5\'s neck to control the
      > tilting
      > > of his head? They look like solenoids, but can u control how much the
      > bar
      > of
      > > a solenoid comes out like that to have fine motion?
      > >
      > > Rob Rivera
      > > http://www.simplesquared.8k.com/
      > >
      > >
      > > [Non-text portions of this message have been removed]
      > >
      > >
      > > Visit the SRS Website at http://www.seattlerobotics.org
      > >
      > > To unsubscribe from this group, send an email to:
      > > SeattleRobotics-unsubscribe@yahoogroups.com
      > >
      > >
      > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
      > >
      > >
      > >
      >
      >
      > Visit the SRS Website at http://www.seattlerobotics.org
      >
      > To unsubscribe from this group, send an email to:
      > SeattleRobotics-unsubscribe@yahoogroups.com
      >
      >
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      >
      >
    • FThompson9@aol.com
      How about putting a long bolt on the end of a motor shaft. Attach motor to collar bone and nut (threaded rod coupler is better) to head. A linear pot for
      Message 2 of 15 , Mar 1, 2002
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        How about putting a long bolt on the end of a motor shaft. Attach
        motor to collar bone and nut (threaded rod coupler is better) to head. A
        linear pot for feedback and you have a linear servo. (A string wrapped
        around the shaft of a ten turn pot could also substitute for the linear pot.)
        If your computer has analog input, you can use it to directly drive an H
        bridge.

        Just a thought
        Pherd
        Somers, CT



        [Non-text portions of this message have been removed]
      • Mark Medonis
        That works, sure. However I found that method too slow for my own animatronic head. In fact, you can buy stepper motors with a threaded shaft running straight
        Message 3 of 15 , Mar 1, 2002
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          That works, sure. However I found that method too slow for my own
          animatronic head. In fact, you can buy stepper motors with a threaded shaft
          running straight thru them. Marlin P. Jones & Assoc. catalog usually has a
          couple for sale. http://www.mpja.com

          A linear solenoid or true linear motor would be preferable for another
          reason, too. In direct drive, under PID control, you can have compliance. So
          if you push against the head, it has a certain amount of give. Much more
          similar to human muscle control, and also aids in shock absorption. This
          compliance is under software control automatically because of the nature of
          PID, just as the compliance in your neck varies depending on how tense your
          neck muscles are.

          The Honda Humanoid robots P2, P3, and Asimo don't use linear motors, BTW.
          They use rotary motors, but have torque sensors on the output shaft for
          force control.

          Mark Medonis

          >
          > How about putting a long bolt on the end of a motor shaft. Attach
          > motor to collar bone and nut (threaded rod coupler is better) to head. A
          > linear pot for feedback and you have a linear servo. (A string wrapped
          > around the shaft of a ten turn pot could also substitute for the linear pot.)
          > If your computer has analog input, you can use it to directly drive an H
          > bridge.
          >
          > Just a thought
          > Pherd
          > Somers, CT
          >
          >
          >
          > [Non-text portions of this message have been removed]
          >
          >
          > Visit the SRS Website at http://www.seattlerobotics.org
          >
          > To unsubscribe from this group, send an email to:
          > SeattleRobotics-unsubscribe@yahoogroups.com
          >
          >
          > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
          >
          >
        • Bob Dyer
          Tom Carroll should step into this discussion. He s developed several robots for Hollywood including Number 5 for the movie Short Circuit. Tom where are you?
          Message 4 of 15 , Mar 1, 2002
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            Tom Carroll should step into this discussion. He's developed several robots
            for Hollywood including "Number 5" for the movie Short Circuit. Tom where
            are you?

            -------------------------
            Consider Carefully... Act Boldly!
          • twcarroll@aol.com
            Bob and the SRS, You sent the following: Tom Carroll should step into this discussion. He s developed several robots for Hollywood including Number 5 for
            Message 5 of 15 , Mar 1, 2002
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              Bob and the SRS,
              You sent the following: "Tom Carroll should step into this
              discussion. He's developed several robots for Hollywood including "Number 5"
              for the movie Short Circuit. Tom where are you?"

              Well, I decided to sit back and watch the different responses,
              rather than doing my usual bit of purposely placing a lively bit of
              controversy on the list server and watching the resulting flames. But, you
              forced my hand, Bob.
              I've been reading the comments about the Short Circuit #5 and the "so
              called" actuator cylinders. This multi-million dollar project by Gary
              Foster, Dennis Jones, Aric Allerd and others used lots of small players like
              me to do sub-systems. I was a full-time engineer at Rockwell at the time
              doing space robotics for NASA. If I recall, those cylinders were dampers
              used as props to simulate actuators. To use pneumatics on a mobile prop is
              quite difficult and noisy. I've seen the robot "opened up for all its glory"
              and I believe the head actuation used an x-y joint with some rather large
              gearmotors attached to move that heavy head. As you might remember, #5 had
              a rather large head with some very heavy surplus optical lens assemblies with
              the motorized irises.
              If the person trying to duplicate the 'apparent motion" of two linear
              actuators, he could use a better version of the "string method" mentioned
              later in the responses. Using two sail winch servos made for R/C sail boats
              and a small diameter steel cable to pull the head in two axes, and using
              springs to counterbalance the mass of the head, I think he could pull off
              this head control quite well. He could use the 1-2 ms pulse train to control
              it with R/C, or use a microcontroller and two sets of "H" bridges to control
              a modified set of servos with software.
              Anyway, that's my two bits,
              Tom


              [Non-text portions of this message have been removed]
            • David VanHorn
              ... I ve always used the working assumption that what you see, in a movie prop, is chosen for it s looks, and what does the work may be entirely different, and
              Message 6 of 15 , Mar 1, 2002
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                At 03:59 PM 3/1/2002 -0500, twcarroll@... wrote:
                > If I recall, those cylinders were dampers used as props to simulate
                > actuators. To use pneumatics on a mobile prop is quite difficult and noisy.


                I've always used the working assumption that what you see, in a movie prop,
                is chosen for it's looks, and what does the work may be entirely different,
                and behind the scenes.

                Come to think of it, the actors more or less follow the same rule :)
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