A journal article on this work should soon be published in the journal Multibody System Dynamics. The title of the article is "Computational modeling and simulation of closed chain arm-robot multibody dynamic systems in OpenSim."

There is no rotation sequence for motion capture data. Mocap data is just (x,y,z) coordinates of markers, which we turn into joint motions (some of which may have rotation sequences associated with them) using an Inverse Kinematics analysis.

I just downloaded the Synchronized Motion Data.zip file for the Fifth Competition, and the synchronised eTibia data for the Overground Gait Trials is there. It appears that this issue was fixed in response to your message.

We were only allowed to release reverse-engineering CAD (i.e., STL) models of the implant components generated from laser scans, since companies guard their actual CAD geometry closely.

If you want to turn a .STL model into a NURBS model, I suggest using Geomagic Design X (formerly Geomagic Studio).

Unfortunately, those data were never processed and have been lost .

So I will now answer my own question :-). My daughter was visiting and she has a Macbook Air with the new Apple M1 chip in it. I installed OpenSim 4.2 on it and did Tutorial 3 involving Model Scaling, Inverse Kinematics, and Inverse Dynamics, plus I tacked on Static Optimization for good measure. Th...

I am curious if anyone has tried running OpenSim 4.x on a Mac with Apple's new M1 chip. I know that no native M1 build exists for OpenSim, so the question is whether OpenSim still works when running in Rosetta 2 emulation mode. If anyone has any experience here, I would love to hear whether or not O...

I have an inverse dynamics analysis question for systems with a closed kinematic chain and a joint rotational axis direction that is 'skewed' and not along any of the parent or child body x, y, or z axes (for example, <axis>0.0048 0.9991 0.0424</axis>). For a model with only open kinematic chains, w...

Thanks Dr. Habib. You were 100% correct.

When I gave the second body close to the correct orientation as its initial orientation, then the weld constraint assembled the bodies exactly as it should have.

I appreciate the fast and extremely helpful response!

I am trying to weld the hand of an arm model to the hand rest of a robot model, but the weld constraint keeps welding the two bodies together with incorrect relative orientation. To explore the issue, I created a box body that I connected to ground with a 6 DOF custom joint. I then welded the box to...