(2019-12-06, 21:09)N. W. Perry Wrote: I think the trouble with that will be that when the hand is rotated, so does the point where the control stick is supposed to sit, because that point doesn't lie on the part's Z axis. I think I'd have to find the rotational disc of this point and compound it with the disc of the arm, which I guess would form, what, some kind of donut? Or I guess it would be a cylinder?
Follow up: No, after messing around with it, it appears to be a donut after all. The combined rotation of the arm and the control point in the hand seems to describe an irregular torus with an elliptical cross section, so its intersection with the sphere would form a tiny ellipse on the surface, and you'd have to figure out which point on that ellipse represents the hand aligned with the stick.
I have no idea how you'd calculate such an intersection, so if we remove the requirement of rotating the hand, we're just left with figuring the intersection points of the arm disc with the lever's sphere—there must be a formula or online calculator out there that can do this, but I haven't found it yet…