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Continuous Rotation Servo — Parallax Forums

Continuous Rotation Servo

Josiah WoodJosiah Wood Posts: 16
edited 2004-09-21 18:30 in Robotics
Can the Continuous Rotation Servos from Parallax make several revolutions or can they just turn 360 degrees?· Also, do they work with the Parallax Servo Controller?· I'm new to robotics and microcontrollers still, so I'm still trying to figure everything out.

Thanks

Comments

  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-09-18 19:50
    By "continuous rotation" that means that they just keep going in the direction your specify (using PULSOUT). This allows them to be used as robot drive motors.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • Josiah WoodJosiah Wood Posts: 16
    edited 2004-09-18 20:12
    So instead of sending a signal that specifies the position you specify the direction? Would I still be able to use the Parallax Servo Controller? Would I be able to get position feedback from it?

    Thanks again.
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-09-18 20:19
    You can connect a continuous rotation servo to a servo controller, but the postion information now becomes speed information (and the speed curve is not linear, so not very useful).

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • Josiah WoodJosiah Wood Posts: 16
    edited 2004-09-18 20:23
    Thanks, that's exactly what I needed to know.
  • sponge johnsponge john Posts: 3
    edited 2004-09-19 15:48
    How long will the servo spin on one pulsout command? Or put another way, does pulsout need to be repeated a certain period to keep it going.

    I'm also trying to sort out in my head how this works. [noparse]:)[/noparse]

    These forums have answered many of my questions, have learned much from reading the other posts.

    Have been on other company's sites and waited a long time for any kind of answer. Here one can get answers very quickly, giving much more confidence to attempt more.

    Thank you
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-09-19 19:48
    Not very long with one PULSOUT -- the servo needs to be udpated every 20 milliseconds or so. Anything from 10 to 40 ms seems to work though.

    You may want to download our Robotics text; it has lots of good information (theory and practical) on using servos as robot drive motors.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • WNedWNed Posts: 157
    edited 2004-09-21 06:45
    Jon,
    I looked around the Parallax site quite a bit, but couldn't find the Robotics text you mentioned. I'm another guy trying to figure out the "correct" way to use CR Servos as drive motors (with the servo controller if practical).
    Thanks for the time you spend helping folks out.
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-09-21 14:14
    Here's a link to the book (PDF): http://www.parallax.com/detail.asp?product_id=28154

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • WNedWNed Posts: 157
    edited 2004-09-21 18:30
    ·· Hello,
    ·· Here's a little calibration program to help folks who are having difficulty understanding how
    Continuous Rotation Servos work with the Parallax Servo Controller. I hope it helps.
    ·· Remember, if you're using two CR servos as drive motors, for both of them to drive your
    vehicle in one direction, the two servos need to be given opposite commands.
    ·· Enjoy,
    ·· Ned

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