Hello again! Still trying to get my rower working with CMC. The previous version had only one arm and worked fine. But after adding the second arm and consequently another kinematic loop it now fails again. Ipopt: Infeasible problem detected (status 2) This exactly after 0.922 seconds. rower.png Her...

Got it to work!
Changed a few things:

• Changed the connection between hand and oar to reduce some coordinate values to well below 90 degrees

• Set the task for the leg to the knee instead of the seat

Added the model again for completeness.
Regards, Sietse

Hello list, My model of a rower in a boat has progressed a bit! Please find the model and all data attached. But regrettably I now again have a problem with CMC. rower.png The model now has 2 kinematic loops implemented using WeldConstraints at the foot stretcher and the starboard outrigger. The pre...

I have been struggling for more than a year with using this model with CMC, and I am now more or less at my whits end. Is there no-one with in-depth knowledge of CMC? Who else can I ask? I really think that my intended model is a relevant use case, think exosceloton. In the accompanying OpenSim issu...

Another point. the Joints uarml and uarmr are CustomJoints, but are actually BallJoints. In this opensim issue we found that CMC does not cope well with BallJoints. Therefore I changed then to there CustomJoint equivalent, and that worked. If I change these CustomJoints back to BallJoints, the simul...

For completeness here the updated zip-file.
It now calculates for the complete 7 seconds.
I included the trajectories in both 100Hz en 200Hz variants, using trajectory.py.
The 200Hz variant fails already after 1 second.

Thanks again for seriously looking into this! I have made some progress, but not much, alas. After setting isEnforced to off, it works! See below for the "but". When it works, CMC delivers its result in ResultsCMC in several sto-files. Then why are you saying: Then, when performing forward dynamics ...

Thanks very much for responding!! I am afraid I don't fully understand. 1. You are talking about first disabling contraints and then enabling them? How do I do that in one single call to the CMC tool? I assume you main the FD algorithm as part of the CMC tool. Otherwise I don't understand it. 2. Whi...

I have asked this before, also as an opensim issue 3679 , but still no solution. Hopefully this time around someone will find something! The model, a few trajectories, IK and CMC setups can be found in CMCerror_2.zip . CMCerror.png Think rower in a rowing boat. The model contains: A custom joint act...

Thanks for the reply! The problem remains when the contact mesh and elastic foundation force are removed, regrettably. This, even simpler, model has the same problem. What could be wrong? Is there an (undocumented) fundamental flaw/restriction in the CMC system, or a bug in its implementation? Is th...