Torsion in a polyline

Hello, 

Browsing through the forum I did not find any discussion related to curve torsion. 

In the image attached, I have a polyline that comes from rhino, manually drawn. Evaluating it with the PerpFrame component I see that at the parameter t (the starting point of each exploded segment) the orientation of the plane differs. Each of this segment lays on its plane (physical surface). I have been trying to play around with vectors in order to adjust it, rotate it and so on, but I cannot find a good solution. 

First, which is the generative concept (from rhino) that makes this happen? how could I redraw the base poly in order to avoid the issue?

Then, in case the above mentioned is not doable, what could the grasshopper solution be?

Thanks

Lorenzo