Hi Louis,
Here are some answers
- Am I right that AnyKinSPSheet wraps the ligament around the bone geometrically, but the sheet does not exert a wrapping force onto the bone?
No not exactly the sheet will act on the underlying surface being a cyl, ellipsoid or sphere. The force will be transmitted from the anchoring point on the surface to the segment it is attached on. So e.g. the muscles wraps a cylinder and create forces along the line, these forces are transmitted to the segment by three forces and three moments in the surface attachment point.
- If "question1." is wrong, and the AnyKinSPSheet does exert a wrapping force onto the bone. Am I right to say this force is not taken into account in the FDK-loop and therefore does not influence the knee-joint-kinematics?
No this is not correct the contact forces will be transmitted to the segment and it will influence the motion of the FDK dofs.
- I read that the class "AnyShortestPathMuscle" does exert a wrapping force. I was wondering whether this class's force is standardly included in the FDK-loop? Is it possible to include it in the FDK-loop to influence the kinematics?
Honestly i have never tried to do this, but i am certain that the contact forces will be accounted for. The FDK is simply an extra loop on the inverse kinematics.
- Is there a way for us to make AnyKinSPSheet influence the kinematics using FDK?
I have never tested this combination but i have absolutely no reason to think that AnyKinSPSheet would ot influence FDK (there could be other reasons for this, e.g. high forcetol or no activity in muscle). The combination of FDK and AnyKinSPSheet will be very slow. In the new AMS version 7.3.0 we have release a beta version of a new muscle wrapping, which is significantly faster than the old version, and for a FDK model this difference will be even bigger. Please see this page on the new AMMR version https://anyscript.org/ammr-doc/changelog.html#whats-new which includes a section on the muscle wrapping. Please also see this announcement on AMS AnyBody Modeling System v.7.3.0 released 🎉
- This would be my strategy to answer "question 4." above. As far as I understood, AnyKinSPSheet uses an iterative loop to find 'points of contact' between the sheet and a surface at each instant.I was wondering if it would be possible to assign a LinearMeasure 'between' 2 points of contact. Then I would assign a calculated force to the LinMeasure and change the CType of the LinMeasure to {ForceDep}.. Is this a reasonable strategy?
No, this will not be possible and the sheet should exert forces to the model and thus change the FDK. One simple question do you have any muscle activity in the sheet muscle? if not you will see no impact.
- I am quite new to AnyBody and not sure whether users commonly have access to the Source code of functions. Is it common or possible for users to see Source code of a couple of Classes and create new classes by e.g. combining features of some classes or writing new code?
I am sorry but this is not not possible you can not change functions and access source code, you can use a python hook to calculate things that is otherwise difficult to do in anyscript.
In your case i would strongly recommend to use regular shortest path lines AnyKinSPLine instead (you can introduce multiple of these instead). With the the new version this will be order of magnitudes faster to calculate than the sheet, so unless you have very specific reasons for wanting to have as a sheet please consider this.
Best regards
Søren