Ambiguous Initial Position


I’m working with a Modell with a prismatic joint that should only take positive values and has two other segments attached, that should be pointing “upward” during the study.
The other two segments sometimes get loaded into AnyBody pointing “downward”, in that case though, AnyBody calculates the Models Initial Position to pointing be pointing downward, too, with negative values of the Prismatic Joint Position.
As I understand, you can’t constrain a joint to only take Positions within a certain range, correct?
I was already thinking about rotating the two segments when they get loaded to make sure they are pointing in certain direction, but that seems like a lot work…especially since there is no function to invert a Matrix, right? (To rotate RefFrames back towards the GRF…or could I use an AnyFunTransform for that?)
Do you have any suggestions?
Thanks in advance!

Hi Katharina,

  1. Actually we are working on the ‘range of motion’ implementation about any kind of kinematic measures.
    So it may be available at our next release. Please keep your attention on our website. :slight_smile:

  2. So the current possible suggestion is to define a soft driver with very low weight factor which will determine the direction of the segment.
    Of course this may affect the original driver. But it may be helpful to set the direction of that segment as what you want.

  3. Regarding the inversion of affine transformation matrix, you can just use the transpose of the matrix instead of calculating the inversion of the matrix directly.
    Of course you can do it in AnyScript because AnyScript has the operator for that (A’).

Best regards,

Thanks Mooki!

I actually ended up rotating the GRF according to how the segments were rotated in the load-in positions…
But you’re right, I could have just transposed the Matrix, too! Also - being a wise a…:wink: - you can do this because it is a orthogonal Matrix,!
Anyways, thanks again!:slight_smile:
Best regards,