Center of Pressure from Elastic Foundation

[Michele Vivian]

Extracting Center of Pressure from Elastic
Foundation Foot-Ground contact model

Hi everybody,

I'm currently working on my master thesis (Dept Information Eng.,
University of Padova).

I am using the OpenSim ElasticFoundationForce class to implement a
foot-ground contact model. I would like to know how to extract the 3D
position of the instantaneous center of pressure (COP) associated to
the ground reaction forces generated during the stance phase.

I was able to get amplitude of the force and the torques through the
ForceReporter class but was not able to get COP kinematics.

Despite the browsing of doxygen documentation and my search in forum
posts I had no luck about the center of pressure issue.

Does anyone know how do it?

Thanks,
Michele

[Sina Porsa]

HI Michele
I want to use "elastic foundation force" to model ground - foot contact. But I have some problems. It seems that you have done it before. it would be great if you could help me.

In order to add "elastic foundation force" to my OSIM file, I added this to my osim file, within my forceset tag:

<ForceSet name="">
<objects>
...
<ElasticFoundationForce>
<isDisabled> False </isDisabled>
<contact_parameters>
<geometry>
<objects> ground pelvis </objects>
<groups> </groups>
</geometry>
<stiffness> 0 </stiffness>
<dissipation> 0 </dissipation>
<static_friction> 0 </static_friction>
<dynamic_friction> 0 </dynamic_friction>
<viscous_friction> 0 </viscous_friction>
</contact_parameters>
<transition_velocity> 0.01 </transition_velocity>
</ElasticFoundationForce>
...

But it is not working and I have no idea what is wrong. It would be great if you could help me.
Thanks
Sina