not enough force platforms

[Pouyan Mehryar]

Hello,

In order for the static optimization and CMC to run successfully I believe we require having at least 3 force platforms so we could implement the external force from the stance phase of the limb on the second platform, What if we only have 1 or 2 force platform? how can we have the proper external load so we could successfully execute SO or CMC?

Is there any algorithm that could predict the external load of your experimental data?



Thank you in advance for your response!

[jimmy d]

OpenSim doesn't have a way of guessing the ground reaction forces if you haven't collected them.

I think AnyBody has a method for making guesses.

[Pouyan Mehryar]

Hi,

Thank you for your response!

Can we manipulate the RRA actuators (Fx, Fy, Fz, Mx, My and Mz) so the model does not fail where there is no external force??

Is there any solution for this problem???

[jimmy d]

Why would you want to run RRA without any external forces?

[Pouyan Mehryar]

I have kinetic information from 2 force platforms however, I dont have the 3rd force platform so I am missing some force data. Static optimization uses Actuators and External Loads so I thought that by changing the RRA_actuators parameters (FX, FY, FZ, MX, MY, MZ) it maybe possible to compensate for the loss information.

Would it be possible to do this?!

[jimmy d]

From the RRA documentation:

The purpose of residual reduction is to minimize the effects of modeling and marker data processing errors that aggregate and lead to large nonphysical compensatory forces called residuals. Specifically, residual reduction alters the torso mass center of a subject-specific model and permits the kinematics of the model from Inverse Kinematics to vary in order to be more dynamically consistent with the ground reaction force data.