Pantographic/ Scissor

Hallo everyone,

as known that a Pantograph or a Scissor works typically at least with 2 bars which are sharing a pivot, and, if needed, a fixed anchor:

there is a interesting topic about it by using kangaroo:

http://www.grasshopper3d.com/group/kangaroo/forum/topics/beginners-...

Daniel made a very nice example, which was done by splitting the lines at their hinge point then adding bending stiffness to keep the line straight.

I know some time we have to deal with software and give some tricky way, e.g. adding bending stiffness or give it a 'invisible' support:

But in reality, all the single bar are actually a rigid element which connected at the end and sharing a pivot in the middle of bar. So I started simulate it with the connections along they length instead of splitting the lines at their hinge.

The problem is, that the system don't behaviour like a truly pantograph. They move very randomized, because I couldn't fix the pivot in the middle of bars. 

Perhaps my approach is wrong, coz it really need deal with something tricky. But I am still wondering, how could I simulate a structure which looks like below.

The blue line is a continue element instead of splitted.

Have anyone an elegant idea?