I have a mechanism and I need to rotate a component (gray) 180° with a pin joint, but I need that the red component always be in vertical position (or bottom surface always parallel to the floor).
I tried different Kind of connections, but always failed. Could anyone help me telling me how can I add a parallel constraint to the bottom surface in order to always have a vertical position in the red component, while gray component is rotating?
If you simply want to keep that orientation while dragging, you can orient two datums as shown (the datum on the left is an assembly datum) and take a snapshot.
Then, whenever you need to drag the assembly, activate the snapshot.
What about adding a dummy link (in green) that constrains the red follower to be in the desired orientation:
The dummy link is constrained by 2 planar connections:
And then the red follower has a pin joint as one of the connections, and a planar constraint that will orient it to the dummy.
The resulting motion is what you seek in your description. The only downside of this method is the dummy component that needs to be handled elsewhere (e.g. layers for visibility, filters for presence in the BOM)...
Assemble the red part with a pin constraint and then add a second constraint set as "General" and make a datum or surface from the red part parallel to one of the assembly datum planes. That will force the red part to remain fixed instead of rotating with your gray part. Very basic example attached.