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Coordinates
2D/3D

Coordinates is an option for Reaction and Loads that specifies whether the force and moment vectors returned are in Global or Local coordinates.
Coordinates is also an option for RelativeVelocity and InstantCenter that specifies whether the results are returned in Global or Local coordinates.
• In Modeler3D, Coordinates is also an option for SetSymbols that determines whether angular velocity and acceleration are calculated in Global or Local coordinates.
• In Modeler3D, Coordinates is also an option for Alpha and Omega that specifies whether angular velocity and acceleration are returned in Global or Local coordinates.

• In Modeler2D, the setting of the Coordinates option for Reaction affects only the value of the force; the moment is a scalar, unaffected by the coordinate system.
• In Modeler3D, the setting of the Coordinates option for Reaction affects the direction, but not the magnitude, of both the force and moment vectors.
• The default setting is Coordinates->Global for all functions accept Loads. The default setting for Loads is Coordinates->Automatic, which causes results to be returned in the modeling coordinate system specified with SetSymbols.
• In Modeler3D, Coordinates is also an option for cylindrical and spherical coordinate conversion functions that specifies the base reference frame for the right-hand rule Cartesian coordinate system. Settings are
XYZ, YZX, and ZXY.
• The default setting for coordinate conversion functions is Coordinates->XYZ.
• See also: CylindricalToXYZ, SphericalToXYZ, XYZToCylindrical, XYZToSpherical.

Further Examples

Load the Modeler3D package and define a simple model.

Here is the angular velocity of the link body in global and local coordinates. Note that the expressions differ only slightly.

Here are the loads applied to the link body in global and local coordinates. Note that the expression for the moment in local coordinates agrees with our knowledge that the moment is applied in the local Z direction with a magnitude of 1.0.

The loads can also be expressed in the modeling coordinate system which, in this case, means that the moment is expressed in Euler parameters space.

See HelpModel3D.


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