Hi all, I find that there is a constraint of minimum activation for Thelen2013 muscle. OPENSIM_THROW_IF_FRMOBJ(get_minimum_activation() < 0.01, InvalidPropertyValue, getProperty_minimum_activation().getName(), "Minimum activation cannot be less than 0.01"); Why has it been added to Thelen2013 muscle...

Thank you very much, Sherm!
Using an implicit integrator solved the problem.
I used the integrator to conduct a forward dynamics simulation. Once the system became stable, I saved the state for the further usage.

Best regards,
Jiang

Hi, Sherm Thank you for your reply. I want to get a stable initial state of the model by static inverse dynamics calculation so that where the contact is occurring is unknown priorly. Instead of using PointOnPlaneContact to represent the contact force, I prefer to adding some constraints for interna...

Hi, Sherm Thank you for your prompt reply. >>However, for a static analysis it can be problematic since stiction forces can't be produced at exactly zero velocity. Is that why you want constraint-based stiction? Yes, I want to conduct static inverse dynamics analysis in consideration of the static f...

Hi all, I found ElasticFoundationForce cannot represent stiction because the friction force is a continuous function of the slip velocity. I added a constraint like code to represent the stiction (see the code below) but such implementation can only be used for a specific situation. Is there any oth...

Hi, Sherman and Dimitar Thank you very much for your reply. Now I understand that I may need an additional actuator to lock the joints. I think it would be better to clarify this point in the OpenSim user guidance, which will help people who are dealing with inverse dynamics problem (e.g., calculati...

Hi all I am trying to conduct the static inverse dynamics to calculate the coordinate forces given the vector Q. I found that the residual force of the locked coordinate is not zero. Does this value mean the force that is needed to apply for satisfy the lock constraint? I also can't totally understa...

Hi all,

I want to create a controller with state estimation by a Kalman filter.
To implement it, I need to calculate the transition matrix and its transpose to calculate
the estimated state.
Does Simbody have the API to access it directly?

Thank you in advance,
Jiang

hi,

It seems that osimModel.updForceSubsystem().setNumberOfThreads()
doesn't work in OpenSim 4.0Beta.
Will OpenSim support parallel force computation in the future?

Best regards,
Jiang

Many thanks! It works now.