Hello everyone. I had a couple of quick questions about the time delay between muscle activation and the onset of muscle force. In OpenSim, is the time delay equal to the time activation constant given by the Thelen muscle model? That's my first question. My next question is whether there is a time ...

Hello Fred, The coordinate limit forces should be in the same section of your model (in the coding which defines the model) as where the muscle forces are. You could use notepad ++. Just open the model file in notepad++, switch the language to xml to make it easier to see, and then search for the te...

Hello everyone, I'm trying to run the induced acceleration analysis. I specify that I want the analysis to be ran for two of the bodies in my model and for three coordinates, but I get the following error: Storage: ERROR - failed to parse header of storage file Has anyone seen this message before an...

Hey, See if there are coordinate limit forces in your model. I had the same issue you had and what helped me was totally deleting the coordinate limit forces. Besides that, make sure you've got at least an actuator for each degree of freedom (a reserve actuator). Try setting the reserve activations ...

Hey Michael,

Thanks for the paper recommendations. I'll look at them.

Brandon

Hello all, Does anyone know of any papers or resources which might describe how the distance between points spanning a joint with a wrapping object is found? For example, if a cylindrical wrapping object is used at the elbow and the triceps long wraps over it, how is the length of that portion of th...

Hello Wang, I actually didn't use any external loads in my model so I'm not sure what would cause your model to crash. Make sure you have a reserve actuator for every joint. Set the control values to positive and negative infinity and set the optimal forces to 1 for each reserve. If there is a joint...

Hello, The difference in what you're seeing is that cmc accounts for both passive muscle forces and active muscle forces. To understand the difference between the two, read the opensim pages on muscle theory. Static optimization only accounts for active forces in the model while cmc accounts for bot...

Hello everyone, I think I determined the source of my problem. I tried disabling the muscles again and simply appending the reserve actuators onto the force set of the model but I also got rid of the coordinate limit force. There are coordinate limit forces in the model, and they will have an effect...

Hey James, What I mean by "turn muscles off" is that I disabled the muscles in the GUI. When I do that and select "append to model's force set" for the reserve actuators, static optimization doesn't work and wont give me solutions even at the very beginning of the motion. However, I tried what you d...