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Steppers - worth the effort? — Parallax Forums

Steppers - worth the effort?

HeadShotHeadShot Posts: 5
edited 2005-03-27 13:52 in Robotics
I have been playing around with the old Howard Industries steppers from Parallax. I can only get them to rotate about 14 degrees per pulse with the PAUSE 10 delay. After figuring out and using the 2803, I can't get enough torque to move the motors with 3 inch wheels. All the books say "Don't bother with steppers for moving your bot."· Lost cause? Or should I continue to figure them out as motors for my bot?

thanks
dan

Comments

  • Robert SchwartzRobert Schwartz Posts: 141
    edited 2005-03-17 23:11
    Unless you need good accuracy, there is no point in using them.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-03-17 23:37
    If you say that your stepper motor is having trouble moving 3 inch wheels, the wayward ant straying in the path of your bot may just hang it up. There are more powerful steppers availible, but if your going to buy something new Id just go for a continuous servo or H-Bridged DC motor, they are less complex to drive than a stepper and unless your using your bot as a giant spirograph (hey anyone do this? Id be cool to see someone make a giant plotter bot), you won't need the positional accuracy stepper's provide you.
  • BeanBean Posts: 8,129
    edited 2005-03-18 00:49
    Stepper motors have greatest torque at their slowest speed. A decent sized stepper usually cannot be held back with your bare fingers, so if the motor cannot turn a 3" wheel I would suspect that you are either not driving them with the proper voltage/current or you are not stepping them with the proper pattern or trying to make it spin too fast.

    As for a drive system. I wouldn't recommend it for a generic robot. They use more power than a servo. and require more interfacing.

    Bean.

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  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-03-26 17:31
    Regarding that GIANT SPRIOGRAPH, I have been trying to get my little two wheeled bot programed to pull a piece of chalk around a parking lot for just that purpose. I suppose you could call it robotic graphitti. Others may call it art. Nonetheless, it may be a way for a robot geek to meet a pretty girl on a Saturday at the park. Let your bot unleash your creativity.

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  • Ray IddingsRay Iddings Posts: 47
    edited 2005-03-26 20:02
    Spirograph...check it out, http://www.parallax.com/html_pages/resources/custapps/app_boebot_art.asp

    I tryed a couple of these out by taping big butcher paper to the floor, my kids loved it and now "porkchop" (our robots name, thats what happens when you leave naming duties to a 4 year old) has a piece of artwork hanging on the fridge too.


    Ray
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-03-27 13:52
    You might be able to get 'end rolls' of newsprint at newpaper publishers. These are 5 or 6 foot wide newsprint rolls and wonderful for large artwork. They are what remains at the end of very large newsprint rolls that are used in printing for your daily newspaper.

    Many many years ago, they were free for the asking, but now there may be a price.

    I wish I could get some in Taiwan, but I just don't know how to ask.

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