How to include the effect of lead screw efficiency in a Simscape Multibody lead screw block

I need to include the efficiency of the lead screw (actually a ball screw) in the mechanism I'm simulating. I put together what I consider a "hack" to include a translating friction that is a function of the input torque, but this seems inelegant and probably inefficient. What are some ways to include this basic parameter of lead screws into a model?

(This question leads to the more global question of whether or not Mathworks will add friction or efficiency to any of the joints in Multibody so that band-aids using Simulink or Simscape Foundation Library aren't necessary.)

Dan

Answer 1

[Andrew]

Hey, what I did to make this work was by creating my own joint of sorts. Basically the lead screw has 2 degrees of freedom here, a translational and a revolute, so i just used each of those joints individually and then controlled the positions of them based on a 1D model based on simulink driveline ratchet leadscrew (https://www.mathworks.com/help/physmod/sdl/examples/ratchet-leadscrew-mechanism.html)

Inside the Friction Model subsystem:

[Daniel Stuewe]

Andrew,

Thanks for the suggestion. I'm going to try to implement it into my model. Couple of quick questions:

Why did you used the Rotational Damper block for the bearing friction instead of a Rotational Friction block?

What is the purpose of the parallel rotational spring and damper coming out of the torque source block?

Thanks again, Dan