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Robot dc motors help

Discussion in 'Robotics & Mechatronics' started by fortion, Aug 26, 2013.

  1. fortion

    fortion Member

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    i am making a robot with a rotating disk of 8KG and diameter of 1.5 ft . i want to rotate this disc using DC gear motor at a speed of 100 RPM . by my calculation that would require a an output power of 30 W . can someone confirm this calculation ??? it looks wrong to me . also if i use four 30W gear motors of different RPMs namely 100 , 200 , 300 , 400 and use them simultaneously to run the disc will the disc achieve 400 RPM ??? will this assembly work ??? i am building this robot as a hobby to compete in robo war on a local level . if anyone can help i will appreciate it
     
  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Why repeat your question?
     
  3. fortion

    fortion Member

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    i found out i had posted my question under the wrong heading and this is the place to pose questions about robot building so i posted it again :(
     
    Last edited: Aug 26, 2013
  4. dave

    Dave New Member

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  5. remon7

    remon7 Active Member

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    Why do u use Disc? and Which purpose(Rotating) ?
     
  6. remon7

    remon7 Active Member

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    Why do you use Disc? And which rotates purpose for what?
     
  7. panic mode

    panic mode Well-Known Member

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    i think he is attempting to build some sort of Hypnodisc clone.
    described disc will have inertia of about I=0.2kg*m^2
    here is nice reference: http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

    btw strapping motors with different speeds together will not make them move at top speed, there will be some equilibrium which is between slowest and fastest. you can imagine strapping turtle and rabbit togeter. rabbit on his own may be fast but - not as fast if he also needs to pull turtle.
     
  8. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Strap a rabbit and a turtle together with some carrots and potatoes. Salt and pepper. Hot water.
    Very hungry.....I should go eat.

    PanicMode I like your picture.
     
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  9. fortion

    fortion Member

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    Panic mode you are absolutely right . i am trying to build a sort of hypn-disc clone. it is supposed to be my first year project. and by the way isn't moment of inertia of a disk 0.5 m r^2.
     
  10. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    What does this have to do with robots?
     
  11. panic mode

    panic mode Well-Known Member

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    yes, that is inertia equation for solid uniform disc of radius R.
    to compute inertia you need to convert all units to same unit system.
    in SI unit of length is meter, not foot.
    1ft=0.3048m
    1.5ft = 1.5 * 0.3048m=0.4572m
    but radius is half of diameter or R=0.2286m
    m=8kg
    I=0.5*m*R^2=0.5*8kg*(0.2286m)^2
    I=0.20903184 kg*m^2

    now compare this to value in my previous post (just rounded to 0.2)
     

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