I have got Plug-in-Gait data with some poor marker placements at the lateral thigh and lateral tibia. This has led to a shift in the orientation of the joint axes with both being rotated externally.
Is there a way to correct this in Anybody before calculation of joint force? Could I for example rotate the tibia so that its frontal plane aligns with that of the foot?
Is it possible to create a virtual marker on the tibia which is offset from the original tibia marker so that the tibia rotation can be corrected. I believe that the alignment of the foot is correct and would like to use it as a reference as to the rotation of the joint axis of the tibia.
I appreciate any input and am happy to clarify what I am trying to say if it is difficult to understand. Many thanks
I would only like to use a virtual marker in order to calibrate the joint axes. I would not like this marker however to be tracked during kinematic analysis. If I change the values in Markers.any this will change the initial guess for the marker positions on the model.
Is there a way to calibrate joint axes with a virtual marker but have the motion tracked by the original marker?
Fundamentally this is possible it will however require a bit of work to do this, since the model is not prepared for this setup specifically.
We have in the model a definition of a knee joint axis which is controlled by two points, but these points are not created to be editable.
If you open the LegTLEM/Seg.any file and search for “BONY_LANDMARK_DEFINED_JOINTAXIS”
you will find the definition of this joint using points.
I would suggest you do the following:
[ul]
[li]use AnyMechObjectExclude to exclude the knee joint (see small example in AnyBodyStudy object in the reference manual)
[/li][li]create your own knee joint definition similar to the one mentioned above
[/li][li]include the new knee joint from your study
[/li][/ul]
So it is possible to do this, and can be done without altering the body model, but it requires a bit of work.