WOLFRAM SYSTEMMODELER

PointGravityWithPointMasses2

Rigidly connected point masses in a point gravity field

Diagram

Wolfram Language

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Click for copyable input
SystemModel["Modelica.Mechanics.MultiBody.Examples.Elementary.PointGravityWithPointMasses2"]
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Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

This model demonstrates the usage of model Parts.PointMass in a point gravity field. 6 point masses are connected rigidly together. Translating such a model results in an error, because point masses do not define an orientation object. The example demonstrates that in such a case (when the orientation object is not defined by an object that is connected to a point mass), a "MultiBody.Joints.FreeMotion" joint has to be used, to define the the degrees of freedom of this structure.

In order to demonstrate that this approach is correct, in model "referenceSystem", the same system is again provided, but this time modeled with a generic body (Parts.Body) where the inertia tensor is set to zero. In this case, no FreeMotion object is needed because every body provides its absolute translational and rotational position and velocity as potential states.

The two systems should move exactly in the same way. The system with the PointMasses object visualizes the point masses in "red", whereas the "referenceSystem" shows its bodies in "blue".

Components (15)

pointMass1

Type: PointMass

Description:

pointMass2

Type: PointMass

Description:

pointMass3

Type: PointMass

Description:

pointMass4

Type: PointMass

Description:

pointMass5

Type: PointMass

Description:

pointMass6

Type: PointMass

Description:

fixedTranslation

Type: FixedTranslation

Description:

fixedTranslation1

Type: FixedTranslation

Description:

fixedTranslation2

Type: FixedTranslation

Description:

fixedTranslation3

Type: FixedTranslation

Description:

fixedTranslation4

Type: FixedTranslation

Description:

fixedTranslation5

Type: FixedTranslation

Description:

world

Type: World

Description:

freeMotion

Type: FreeMotion

Description:

referenceSystem

Type: SystemWithStandardBodies

Description: