What is the Model of Joint Friction?

[AlanSunHR]

Hi everyone,

In the API of ArticulationView, there is a function named set_friction_coefficients (The joint friction can also be set in the UI).

However, I can not find an explanation of this joint friction coefficient in the documentation. I guess this is the coefficient of a friction model of the joint. Can you help explain the friction model used in Isaac Sim?

Thanks!

[rthaker]

Hi - Sorry for the delay in the response. Let us know if you still having this issue/question with the latest Isaac Sim 2022.2.1 release.

[AlanSunHR]

Hi,

I am still not able to find the documentation about the joint friction. I guess it is something related to PhysX engine? Could you please tell me where I can find more information about it?

Thanks a lot!

[dgarcialopez]

Hi @AlanSunHR

set_friction_coefficients is explained in the documentation here

Hope it helps!

[AlanSunHR]

Thanks @dgarcialopez !

But I am curious about how friction coefficients affects the behavior of the joint. My robot has several servo motors with high reduction ratios, while not activated, they have a noticeable rotational friction. I want to make the motors in Isaac Sim to be close to the real ones, but I do not know what values are proper ones.

My assumption is that, the coefficients may determine the minimum torque needed to move the link, but it seems that it is not correct.

Do you have any experience of that? Thanks!

[toni.sm]

Hi @AlanSunHR

The following link can provide a little more information

https://nvidia-omniverse.github.io/PhysX/physx/5.1.3/_build/physx/latest/class_px_articulation_joint_reduced_coordinate.html#_CPPv4N36PxArticulationJointReducedCoordinate22setFrictionCoefficientEK6PxReal

[AlanSunHR]

Thanks @toni.sm !