How to simulate Coulomb static friction in a multi-body system in SIMULINK/SimScape language?

I'm trying to simulate a multibody system including Coulomb static friction.

So far I have been able to write the equations . I have also been able to implement the math in Modelica language and run the code in both OpenModelica and Wolfram SystemModeller. The issue is that the simulation take like ages. I want to try and do it in SIMULINK/SimScape to see if it is any faster. I have found some SIMULINK/SimScape blocks, but the issue is first I do not understand how they work and they seem to only include kinetic friction. so my questions:

1. Is my math correct ?
2. Are there any easy examples of a multibody system including the Coulomb static friction compatible with my math?
3. Is it possible to program in SIMULINK/SimScape language without using the visual programming interface, like OpenModelica?

Answer 1

[Steve Miller]

Hi Foad - you can model this in Simscape, either in a textual format or in a graphical editor. Attached is a Simscape model and a screenshot is below. I suspect the slow simulations are caused by the transitions from non-sliding to sliding and vice-versa which can be tricky for solvers. The model I have attached simulates extremely fast. I'm not sure if I have matched all your parameters. Your mus is 1.3, which I assume is static friction. Normally coefficients of friction are between 0 and 1, so I'm not sure how to interpret that.

Good luck with your project!

--Steve