RotationalCoupling

[AHaumer]

Address #4012:

• Moved RotationalCopling to Modelica.Electrical.Machines.Utilities.
• Used IdealGear(ratio=-1) inside the coupling.
• Imrpoved documentation.

[dietmarw]

I think this implementation is much cleaner. However, the comparisonSignals and test models introduced in #3786 should get removed/updated

[tobolar]

I'm convinced with this solution.

But sorry for bother you again - I'm still stumbling upon the icon. To me, it makes an impression of a jaw coupling (#4012 (comment)) which in fact enables some very small relative rotation between the two flanges a and b - in fact, it is limited mechanically.
In contrast, considering the example Modelica.Electrical.Machines.Examples.DCMachines.DCPM_Drive, the relative angle between the two machines dcpm reaches several hunderts of radian.

We have obviously different points of view - while I'm focused on that one component only, you consider the whole drive test rig. Located in the Electrical library now, consider this as my last comment on this component and feel free to design the icon on your own.

[christiankral]

To have the coupling more obvious in the simulation example it would make sense to add two rotational speed sensors. The doumentation could then refer to speedSensor1.w and speedSensor2.w.

[christiankral]

OK for me.