Hi Koen, Here are three things I would check: 1) If you're applying ground reaction forces to the model during inverse dynamics, you may want to check that those values are reasonable, and are in the correct units. 2) Are you using OpenSim's built-in filtering when you're doing inverse dynamics? If ...

Hello, I want to compare the work done by all the muscles to the change in kinetic and potential energy of the model. I'm calculating the work done in the following manner: 1) Run Static Optimization to get muscle forces. 2) Run "Muscle Analysis" to get muscle lengths. 3) Differentiate those lengths...

Hi Yuma,

IPOPT is OpenSim's built-in optimizer. CFSQP is a different optimizer that must be obtained separately from another source. Past links to it seem to have expired, so I don't know where it can be obtained from.

Hope that helps,

Stephen

Hi Sultan, I ran into a similar problem, and was able to correct it by setting the environment variable and running OpenSim 3.0 with full administrator privileges. Here's the page related to the problem: https://simtk.org/forums/viewtopic.php?f=91&t=3967&p=8949&hilit=previewing+trc+file#p8949 Best, ...

Hi Zhen, RRA may change the kinematics to be more dynamically consistent with the ground reaction forces. If you're using the RRA kinematics in CMC, that may explain why there is a difference. If you're using the original kinematics file, I would suggest increasing the tracking weights in your CMC s...

Hi Zhen, In the output file from BodyKinematics, it states: This file contains the kinematics (positions and orientations, velocities and angular velocities, or accelerations and angular accelerations) of the centers of mass of the body segments in model workerModel. You could place a point at the C...

Hi Zhen, If you want to apply a force to the COM of the femur, there are two options that I'm aware of. If anyone else has a better idea on how to do this, feel free to pass that on. 1. Use the Analyze/Body Kinematics tool to compute the COM positions of all the segments. Add the COM positions of th...

Hi Zhen, Regarding your question on adding the force to the femur. You can modify your ground reaction force .mot file to include other forces. The important thing is to follow the correct format. Forces columns in the x, y, and z directions should be in the following format: name_vx, name_vy, and n...

Hi Ayman, Running the RRA executable in my loop prevents the memory usage increase. Thanks for the tip with that. I'm planning on continuing to use the executables with my loops, but just to follow up with the previous issue: My memory usage was increasing about 30mb for each iteration. You mentione...

Hi Zhen, Depending on the force data you have, you can apply either a point or body force to the model. The body force will be applied to the COM of the body you specify. There is more information on both of these approaches on the following page: http://simtk-confluence.stanford.edu:8080/display/Op...