Search found 19 matches

by Anantharaman Gopalakrishnan
Thu Mar 06, 2014 1:44 pm
Forum: OpenSim
Topic: Setting the system state in a model with constraints
Replies: 1
Views: 504

Setting the system state in a model with constraints

Hi, I've been trying to use the API to compute moment arms for my musculoskeletal model for different values of the generalized coordinates. Out of around 15 dofs in the model, only 4 are truly independent and each of the remaining 11 are functions of one of the 4, linked through a 'CoordinateCouple...
by Anantharaman Gopalakrishnan
Wed Jun 26, 2013 5:09 am
Forum: Matlab-Opensim Interfaces
Topic: Creating wrapping surfaces
Replies: 1
Views: 567

Creating wrapping surfaces

I am trying to read an opensim model described in a .osim file into MATLAB, and then add a wrapping ellipsoid to the same. % I first initialize an empty WrapEllipsoid object W = WrapEllipsoid(); However beyond this point, I am not sure how to specify the dimensions, translation and XYZ rotation of t...
by Anantharaman Gopalakrishnan
Thu Aug 04, 2011 5:10 pm
Forum: OpenSim
Topic: Exporting SIMM files in OpenSIM
Replies: 3
Views: 792

RE: Exporting SIMM files in OpenSIM

I am using version 2.2.1. All earlier versions seem to export the "moving muscle points" as fixed points when converting into the SIMM format. This leads to unreasonably high passive forces the affected muscles due to over-stretching. Thanks!
by Anantharaman Gopalakrishnan
Thu Aug 04, 2011 6:43 am
Forum: OpenSim
Topic: Exporting SIMM files in OpenSIM
Replies: 3
Views: 792

Exporting SIMM files in OpenSIM

<t>When I export the gait2354.osim model into the corresponding joint and muscle files (Using OpenSIM version 2.2.1), SIMM fails to read in the muscles with "Moving Muscle points" such as the rectus femoris and the vastus. Is there some edit to the muscle file I could manually perform, so that these...
by Anantharaman Gopalakrishnan
Fri Apr 22, 2011 12:37 pm
Forum: OpenSim
Topic: External loads in CMC
Replies: 1
Views: 319

External loads in CMC

<t>Hi,<br/> One of the settings for CMC requires the user to specify a file containing "Kinematics for External Loads". This is by default always the IK motion file. I presume this has something to do with specifying Ground reaction forces during walking, since CMC does not use a ground contact mode...
by Anantharaman Gopalakrishnan
Mon Jun 28, 2010 9:10 am
Forum: OpenSim
Topic: Reserve actuators in CMC
Replies: 0
Views: 193

Reserve actuators in CMC

<t>Hi,<br/> <br/> I was looking at how the reserve actuators work during CMC. It seemed like although their excitations remained constant during a time step (T=<t<T+0.01) the reserve actuator forces took on a different value at the start of the timestep (i.e at t=T). <br/> <br/> My understanding is ...
by Anantharaman Gopalakrishnan
Thu Oct 22, 2009 7:18 am
Forum: OpenSim
Topic: Inertia matrices reported in OSIM file....
Replies: 0
Views: 195

Inertia matrices reported in OSIM file....

Hi,

The moment of inertia tensors for each body segment are reported in the osim file. Are these values taken w.r.t the center of mass of the body segment or the origin of the body frame??

Thanks
Ananth
by Anantharaman Gopalakrishnan
Thu Sep 24, 2009 10:45 am
Forum: OpenSim
Topic: constraints on CMC cost function....
Replies: 0
Views: 225

constraints on CMC cost function....

Hi,

During static optimization in CMC, how many equations are used as constraints on the cost function??

Regards
Ananth
by Anantharaman Gopalakrishnan
Wed Sep 16, 2009 8:45 am
Forum: OpenSim
Topic: How can I see the joint moment?
Replies: 12
Views: 1629

RE: How can I see the joint moment?

Are you referring to the 'joint moment' (Moment required to actuate the joint) or the 'joint reaction moment' (Moment of forces at joint contact, about the joint center)???

For joint reaction moment, you would have to use the 'JointReaction' analysis from the analyze toolbox.
by Anantharaman Gopalakrishnan
Tue Sep 15, 2009 11:29 am
Forum: OpenSim
Topic: JointReaction analysis.....
Replies: 4
Views: 625

RE: JointReaction analysis.....

<t>Thanks Matt,<br/> <br/> But the RRA states file only contains the joint coordinates and their velocities. So shouldn't we include the RRA controls file so that the values of the residual forces and joint actuators are known?? ..... and these would affect the values of the joint reaction forces. <...