Search found 81 matches

by David John Saxby
Sat Jul 06, 2013 3:17 pm
Forum: OpenSim
Topic: muscle analysis vs direct API computation
Replies: 3
Views: 664

Re: muscle analysis vs direct API computation

Hi Ayman,

Thanks so much! A colleagues suggested equilibrate muscles, but and it would have been the next thing we tried, but the defaults would have been another story.

We'll implement those changes, check that we get the same outputs, and then post again with our results.

Thanks very much,

David
by David John Saxby
Fri Jul 05, 2013 1:14 am
Forum: OpenSim
Topic: muscle analysis vs direct API computation
Replies: 3
Views: 664

muscle analysis vs direct API computation

Hi All, Let me describe the problem. I have a large data set and part of the processing pipeline is to compute MTU lengths and moment arms for various modes of gait (walking, running, cutting, etc...). I have successfully used the API via Matlab scripts to run muscle analysis, but seeing as I'm only...
by David John Saxby
Tue Jun 11, 2013 6:52 pm
Forum: OpenSim
Topic: Can the Vicon PluginGait marker set be used in OpenSim?
Replies: 3
Views: 1696

Re: Can the Vicon PluginGait marker set be used in OpenSim?

Hi,

I believe you will need at least 3 markers per segment/body to do ANY 3D motion analysis. This is not a unique demand of OpenSim.

Plug-in gait has 3 markers on each segment. Otherwise it cannot compute direct kinematics or ID.

David
by David John Saxby
Tue Apr 23, 2013 3:10 pm
Forum: OpenSim
Topic: ID output
Replies: 8
Views: 595

Re: ID output

Hi Karen, No idea about jython. I use the matlab wrappers to access the API. Forgive the basic question: is there a setOutputGenForceFileName()? Get and set are present using the Matlab scripting, not sure how jython script would address the same issue. How do you set other values or files in your s...
by David John Saxby
Tue Apr 23, 2013 1:04 am
Forum: OpenSim
Topic: ID output
Replies: 8
Views: 595

Re: ID output

Karen,

If you look in the xml file for the ID setup you'll find

1) results directory. You can set the path so your output goes to a nice place.

2) output_gen_force_file. This is the name of the output file. You can change it, manually or through some code.

Cheers,

David
by David John Saxby
Tue Apr 16, 2013 7:19 pm
Forum: OpenSim
Topic: Freezing while Adjusting Marker Data
Replies: 4
Views: 1236

Re: Freezing while Adjusting Marker Data

Hi Ayman,

I'll post a bug report and include the model, setup files, and data.

David
by David John Saxby
Thu Apr 11, 2013 7:13 pm
Forum: OpenSim
Topic: Freezing while Adjusting Marker Data
Replies: 4
Views: 1236

Re: Freezing while Adjusting Marker Data

Hey, I've had that problem when I turned off the model scale and tried to only use the reposition/adjust markers process. What I usually do is leave the scale model process active, but set the scale factors to unassigned or manual scales of 1. This keeps the model from being scaled (if that is what ...
by David John Saxby
Tue Apr 09, 2013 7:20 pm
Forum: OpenSim
Topic: Basic Questions about the Functionality
Replies: 19
Views: 2686

Re: Basic Questions about the Functionality

Hi Fabian, I can comment on what I know OpenSim can do through my own experience, but I think generally you will find most of your goals can be satisfied by OpenSim in theory. 1) Yes you can solve for muscle forces in OpenSim through static optimization and/or CMC. Or potentially by creating your ow...
by David John Saxby
Sun Mar 17, 2013 10:03 pm
Forum: OpenSim
Topic: Performing Inverse Dynamics via Matlab API
Replies: 30
Views: 10488

Re: Performing Inverse Dynamics via Matlab API

Hi Ayman, Your suggestions worked very well. For ID: I looked at the source code for DynamicsTool to understand the construction of external loads by ExternalLoads constructor. Once made, I set the ID tool's external loads to the new file created. Works! On an unrelated note, have you guys had any b...
by David John Saxby
Fri Mar 15, 2013 4:12 pm
Forum: OpenSim
Topic: Performing Inverse Dynamics via Matlab API
Replies: 30
Views: 10488

Re: Performing Inverse Dynamics via Matlab API

Hi Ayman,

Thanks a lot!

I'll give it a go and report back on the forum how it went.

David