Bifold panels


#1

Hi!
I’m trying to animate bifolding panels like the ones in the image attached. For such the top panel needs to rotate as the second one moves and rotates without disconnecting from the top panel. Has anyone done this successfully? Any advice would be greatly appreciated.

Thank you!


(Luc Adriaenssen) #2

This kind of mechanisms can be solved by using either Forward Kinematics or Inverse Kinematics (IK)
May I suggest you take a look at the tutorial video on Bongo’s website http://bongo.rhino3d.com/video/whys-of-ik explaining the basics of such.

Shutters.3dm (78.4 KB) shows a example of both options.
In both systems the panels are linked in a Hierarchical chain (making the lower child of the top panel) and the top one is rotated via keyframes. To make the panels rotate along the appropriate axis their pivots are moved to the top (using the BongoMovePivot command).

In the FK version I used an expression (-#Object 1.RotateX#*2) to make the lower panel fold back. One could also give it individual rotation data (-170° at keyframe 50). But then using an expression gives you the opportunity to manipulate the hole system via only a single (not double) keyframe-set controlling the angle, speed etc…

Only when both panel have the same height the Forward Kinematic version is this simple. Various lengths or more complex hinging mechanisms make Inverse Kinematics a more practicable angle of incidence.
To conceive the IK structure it’s best to look at the real life shutter and examine were the hinges and the sliders are located.

If any more questions, just ask.