Hi Sherm,

It's all clear now, thank you for your help!

Best regards,
Simone

Hi Sherm, Thanks for the feedback. With sufficiently tight accuracy values (1e-6 in my case), the integrator takes enough steps during the transition. Regarding question (b), if the reporting period is much smaller than the average step size, is the system solved at the reporting step, or is interpo...

Hi, I have a system upon which a force of the following type is exerted: Screenshot 2024-08-02 123917.png That is, at a certain point, the force smoothly increases from 0 to its peak during a very short transient of a few milliseconds. In most scenarios, I guess this transient is irrelevant, but in ...

Hi, I just wanted to post a summary of the results/thoughts I got using different methods, in case it might help anyone. I tried the following to model a Coulomb-like friction force (with a sign function discontinuity and depending on a reaction force): a) Using an auto-update state variable to calc...

Hi Sherm, Thank you very much for the reply, and apologies for my late reply as well. (b) I'm not yet confident about extending Simbody, but please if anyone reading interested in this feature wants to submit a PR, it would certainly come in handy. (a) Clay's approach is indeed very interesting! Whi...

Hi, I have two questions about the integration of the EOM: a) The system under study implements a force F=-A*sign(v), where A is a constant and v is the speed of the point where the force acts. The actual implementation smoothes the sign() function to avoid integration issues. The problem of the lat...

Hi Sherm,

I am connecting the dots now, many thanks for your valuable help!

Best regards,
Simone

Hi Sherm, Yes, I will apply it as body forces! The mobilizers are actually following a unit speed trajectory, so the equivalent body force should be along the tangent to the trajectory, with the same magnitude as the mobility force. Moreover, I noticed (for example in a system with 1 slider along th...

Hi Sherm, Thank you, with the documentation and the example I could create a minimal system that allocates an auto-update variable. Now I am still trying to find a way to compute the needed reactions. Let me explain it again with the following basic system: diagram.PNG The system consists of two sli...

Hi Sherm, Regarding the reaction force, where should I be setting the allocated auto-update discrete variables? And by auto-update does it mean that, no matter when I set the value, it will be updated only after a step finishes? As for the actual friction force calculation, it does not directly depe...