Kinematic Constraints in Motion Files for 4.0

[Jonathan Mortensen]

I know this won't matter for most users, but are kinematic constraints are resolved differently from motion files in 4.0 as compared to 3.3? I have manually created a motion file for a model that includes kinematic constraints for lumbar vertebrae. To make it easier, I did not generate motion data for any coordinates that are dependent on other coordinates (kinematic constraints). If I load this motion in 3.3, the kinematic constraints are applied and the motion looks as I would expect. If I load this motion in 4.0, the coordinates I didn't specify data for remain at default values regardless of kinematic constraints.

This isn't a problem when running SO, as the kinematic constraints are applied. I also know this won't be a a problem if inverse kinematics is used. However, it would be nice to be able to have these constraints when just loading a manually generated motion file. Is this possible in 4.0?

Thanks!

[Aaron Fox]

Hi Jonathan,

I think I came across a similar issue recently where certain joint motions were coupled to ones I prescribed in a similar fashion to what you mention (i.e. manually prescribed these joint angles), and also noticed these don't come in when the motion is loaded into 4.0. I got around this by running a kinematics analysis with the analyze tool, and this generated the additional coordinate data for those that were coupled in the tool outputs.

Hope that helps,

Aaron