UsdPhysics.SphericalJoint position keep fluctuating

[Viru97]

Untitled.design.mp4

I am trying to create rope with rigid bodies connected with joints, but rope keep moving even when disturbed as you can see in the video.

this is how i am creating joints between rigid bodies. Could you tell me whats is the problem and also is it a correct way to create joints?

`@classmethod
    def bead_joint(cls, num_bead, radius):
        ENV_REGEX_NS = "/World/envs/env_0"
        stage = sim_utils.SimulationContext().stage

        # Start at 1 so that (i-1) is always valid.
        for i in range(1,num_bead):
            joint_prim_path = f'{ENV_REGEX_NS}/rope/bead_{i - 1}/joint_{i}'
            joint = UsdPhysics.SphericalJoint.Define(stage, joint_prim_path)
            joint.CreateJointEnabledAttr(True)
            joint.CreateBody0Rel().SetTargets([f'{ENV_REGEX_NS}/rope/bead_{i - 1}'])
            joint.CreateBody1Rel().SetTargets([f'{ENV_REGEX_NS}/rope/bead_{i}'])

            # Set both local positions to zero if the joint is at the bead's center.
            joint.CreateLocalPos0Attr().Set(Gf.Vec3f(0.0, -radius, 0.0))
            joint.CreateLocalPos1Attr().Set(Gf.Vec3f(0.0, radius, 0.0))

            # Optionally, set joint rotations if needed.
            rotation = Gf.Quatf(0,0,0,1)  # Identity rotation
            joint.CreateLocalRot0Attr().Set(rotation)
            # joint.CreateLocalRot1Attr().Set(rotation)

                # joint.CreateLocalRot1Attr().Set(rotation)  # Rotation relative to Cube2
            prim = joint.GetPrim()
            drive_api = UsdPhysics.DriveAPI.Get(prim, "angular") or UsdPhysics.DriveAPI.Apply(prim, "angular")
            stiffness = random.uniform(10,50)
            damping = random.uniform(10,50)
            drive_api.CreateStiffnessAttr().Set(stiffness)
            drive_api.CreateDampingAttr().Set(random.uniform(10,50))
            print('Joint Created')
        return stiffness, damping`

[RandomOakForest]

Thank you for posting this. The simulation shows there may be some physics tuning to do. Have you tried for example, changing the mass of the objects, as it may be too high. Try changing the contact offset on the table when objects are resting. Review collisions settings. The envelope of each link should have a mesh and this may need to be adjusted as well.