Physical (méchanical properties modification) for an imported urdf or step

[aubinadjanohoun]

Hi.
I am trying to specify the inertias for the elements of an imported urdf file. And by inertia i mean the whole inertia matrix, not just the diagonal elements.
I want to do it with a python script so that, together with changing mass and/ or density , i could test differents robots behaviour depending on the real life material.
Using the RigidPrim i can only modify mass and density but not the inertias.
How can i acheve this?
This link can help putting some context here.

[Sirens_uk]

@aubinadjanohoun

o that, together with changing mass and/ or density , i could test differents robots behaviour depending on the real life material.
Using the RigidPrim i can only modify mass and density but

Could you script a dynamic value that uses a varying additional mass modifier which uses a quaterion to change the standard gravity direction to represent it? Also look at which physx model you are using.

i’m not super versed in this, but I think i know what you mean… that is not an easy problem.

[AlesBorovicka]

The mass properties are stored in USD using UsdPhysicsMassAPI:

PixarAnimationStudios/USD/blob/release/pxr/usd/usdPhysics/schema.usda#L194

You could access directly the MassAPI and set the diagonal inertia together with the principalAxes.

Regards,
Ales