[Feature] Joint friction / frictionloss

[YilingQiao]

Description

Support joint friction

Try

import genesis as gs

gs.init(backend=gs.cpu)

scene = gs.Scene(
    sim_options=gs.options.SimOptions(
        dt=0.02,
    ),
    viewer_options=gs.options.ViewerOptions(
        camera_pos=(1.5, 1.0, 1.5),
        camera_lookat=(0.0, 0.0, 0),
        camera_fov=60,
    ),
    show_viewer=True,
)
franka = scene.add_entity(
    gs.morphs.MJCF(
        file="xml/frictionloss_pendulum.xml",
    ),
)
scene.build()

for i in range(10000):
    scene.step()

You should be able to see the static joint friction

frictionloss.mp4

And you can also run the tests

pytest -s -v tests/test_rigid_physics.py::test_frictionloss

Related Issue

#1453

Resolves Genesis-Embodied-AI/Genesis#

Motivation and Context

How Has This Been / Can This Be Tested?

Screenshots (if appropriate):

Checklist:

• I read the CONTRIBUTING document.
• I followed the Submitting Code Changes section of CONTRIBUTING document.
• I tagged the title correctly (including BUG FIX/FEATURE/MISC/BREAKING)
• I updated the documentation accordingly or no change is needed.
• I tested my changes and added instructions on how to test it for reviewers.

• I have added tests to cover my changes.
• All new and existing tests passed.

[Kashu7100]

This is awesome!!!