Here is code that solves the tracking problem with compliant tendons. This code assumes a model "2D_gait_complianttendon.osim" where ignore_tendon_compliance is set to false for all muscles (attached - could also be done programmatically). This is not thoroughly tested and could no doubt be improved...

Hello Karthick, I have solved this example problem using compliant tendons. I do agree with Chris that in some cases using activation dynamics alone is sufficient. For example, De Groote et al. (Ann Biomed Eng, 2016) found that the forces predicted in walking using rigid and compliant tendons were n...

First, I would like to thank Chris Dembia, Nick Bianco, and the rest of the team for all of the work they have put into Moco to bring optimal control techniques to OpenSim. When I started digging into Moco I noticed one of the examples I was most interested in, prediction of human walking by Antoine...

Hi All, Sorry for not responding sooner. I thought if there was more activity in this thread I would be alerted by SimTK via email (maybe that only happens if you initiate the thread), thus I didn't realize until yesterday how much further the conversation had progressed. Chris: I'm happy to help ou...

Hi All, Ton and Ross Miller recently pointed me to this interesting discussion. My group is also intent on using collocation techniques to solve optimal control problems using OpenSim. As a first step in that direction, my former postdoc (Leng-Feng Lee) and I just published a paper that describes an...

Hi Casey,

I'm not positive, but I think if you want to use two different controls files you may need to add two different controllers to the model, one controlling muscle1 and another controlling muscle2. Can anyone confirm this?

Cheers,
Brian

Hi Ryan,

I think this example from the documentation may be helpful:

http://simtk-confluence.stanford.edu:80 ... Simulation

Cheers,
Brian

Hi Stefan, In addition to checking the quality of the scaling and IK results as James suggested, how do your center of pressure data look? The center of pressure can sometimes be a bit noisy around heel strike and toe off (i.e., at the beginning and end of double support). We have seen noisy joint m...

Hi Pouya, Once you have a motion loaded in OpenSim, such as an inverse kinematics result, you may plot muscle-related variables (such as moment arms) against the motion, rather than against a specific joint angle. In the Plotter, for the X-Quantity, select your motion (it will be near the bottom of ...

Last month, I asked about obtaining whole-body center of mass kinematics. This is in the context of running a forward simulation to evaluate the objective function for an optimization problem. I have one case where I only need to know the CM kinematics at the initial time and the final time. Ajay’s ...