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Thread: Dynamics Help Is it possible ?

  1. #1
    Registered User 3dhotshot's Avatar
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    Dynamics Help Is it possible ?

    Scene file here not finding success to make the ball make the wheel turn ....

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  2. #2
    RETROGRADER prometheus's Avatar
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    The wheel is set to kinematic, you can not push a kinematic object with the help of another rigid body.

  3. #3
    Registered User 3dhotshot's Avatar
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    ALRIGHT so whats the right way to make it work....

  4. #4
    Steam username: Carm3D Carm3D's Avatar
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    Maybe a bullet motor on the wheel to make it turn?
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  5. #5
    Registered User 3dhotshot's Avatar
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    I was trying to make it turn with just the ball rotating

  6. #6
    Steam username: Carm3D Carm3D's Avatar
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    Maybe you would need to model some ledges on the inside for the ball to get caught in. If there's no resistance I would imagine there would not be much rotation caused by the ball.
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  7. #7
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    You may also need some kind of spring constraint to press the ball into the wheel.

  8. #8
    Registered User darkChief's Avatar
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  9. #9
    Electron wrangler jwiede's Avatar
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    Quote Originally Posted by 3dhotshot View Post
    I was trying to make it turn with just the ball rotating
    Aside from ensuring the wheel isn't kinematic, you'll need quite a bit of friction between ball and wheel (inner and outer wheels, if you keep that config) for the ball rotation to transfer into the wheel(s). As noted, having a spring pressing everything together might not hurt either. This kind of stuff works fine in C4D's Bullet (with just high friction), but I should mention I've had problems getting LW's Bullet to properly "transfer rotation" between circular objects (gear-type shapes seem to work more reliably).

    Making the ball have some uniform projections, and putting some "steps" inside/outside the wheels might help. Try to make sure the scale is decently large (as in ball and wheel(s) in meter scale), and try to boost up the mass of the ball pretty high as well (with wheel significantly lower).
    John W.
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  10. #10
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    I'm not an expert, but I think the only force that's going to turn the wheel in this model setup is either (a) the force of the ball against the side of the small cylinder, or (b) the very slight imbalance caused by the ball being offset from the symmetric center of the wheel. Neither of these is going to be very large, and the friction of the axle and bushing may exceed their ability to move the wheel.

    Also, even if you do get the wheel to rotate by moving / rotating the ball, the wheel will only rotate until the small cylinder is at the bottom, inertia will move it slightly up the opposite side, and then it will reverse several times until it damps down and stops with the small cylinder at the bottom. No matter what you do to the ball, the wheel will mostly remain stationary with the small cylinder's weight at the bottom of the wheel.

    What are you actually trying to accomplish? This seems like an odd variation on a planetary gear system, so you might research those for more standard, real-world rotary motor systems similar to this.

    Good luck!
    mTp

  11. #11
    Super Member XswampyX's Avatar
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    Quite.

    The only way I could get it to work was drive the wheel and let the ball bounce around free inside it.

    What are you trying to achieve?

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  12. #12
    LightWave Fan Boi
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    Challenge accepted!

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