Applying External Force

[Sahand Ghodrati]

Hello All,

I am attempting to model ~10,000 N of force (upwards from the ground, on the hoof) on a horse limb. I'd like to use SIMM to model this force and understand that "external forces" in Dynamics Pipeline is the best way to go about it. The tutorial says that the code to apply these forces is located in apply_external_forces() in pipetools.c. Does anyone have any advice as to how I should write the necessary code for this experiment? I already have the SIMM file of the limb, just need to apply the force. I'm very inexperienced with open source software so please excuse my incompetence.

Sahand Ghodrati
Exercise Biology Major
University of California Davis

[Daniel Jacobs]

Hello,
I can't tell you about how to do this through SIMM but I can give you an idea of how it might work through Opensim. It's not also not clear whether your mean forward or inverse dynamics but based on your question I will assume inverse dynamics.

Here's how I think it will go:
1) Convert model from SIMM to OpenSim
-http://simtk-confluence.stanford.edu:80 ... IMM+Models
2) Create a .mot file of your desired applied force
-http://simtk-confluence.stanford.edu:80 ... t%29+Files
3) Create an .xml file that describes how the force is applied
-http://simtk-confluence.stanford.edu:80 ... amics+Tool (Scroll down to External Load Specification)

Hope that helps,
Daniel

[Sahand Ghodrati]

Thanks very much, I'll try this and I hope it turns out to be this simple!

Regards,

Sahand