Angular velocity

Multibody dynamics technique, real objects and its dynamical models

Angular velocity

Postby kjjbryan » Mon Feb 16, 2015 10:05 am

If I have body1 rotating both around body2 and also around itself, how do I measure each angular velocity separately. The wizard of variables seems to only provide one measure that includes one angular velocity.
kjjbryan
 
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Re: Angular velocity

Postby Vladislav Yazykov » Tue Feb 17, 2015 8:16 am

Any body in UM should have a joint connecting it to another body. If you need to output angular velocity of one body relative to another one, use the "Angular variables" tab of the Wizard of variables. It has such a feature, see the "Relative to body" group.
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Re: Angular velocity

Postby kjjbryan » Tue Feb 17, 2015 10:47 am

Using /samples/education/sky, How would I measure 1. angular velocity (magnitude) of earth centre around the sun 2. angular velocity (magnitude) of earth around its own axis
The "Ang Var" tab of the wizard has no facility to measure 2. and appears to measure 1+2 when you use the "relative to body" group.
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Re: Angular velocity

Postby Vladislav Yazykov » Tue Feb 17, 2015 4:56 pm

In this model, there are no rotational degrees of freedom. Actually, all bodies are material points. So:
1. The angular velocity of Earth around the sun can be calculated by using components of linear velocity of Earth relative to the sun and radius-vector value. Use the "Expression" and "Linear variables" tabs in the Wizard of variables.
2. There is no angular velocity of Earth around its own axis in this model. Earth is a material point here.
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