Cannot create a fixed joint between realsense camera and its stand

[arambarricalvoj]

Hi everyone!

I’m assembling my robot and trying to add a Realsense camera. However, when I try to add a fixed joint between the camera and its stand, the joint is visualized in red, as shown in the picture, and thus, not working. The only way I managed to solve it is by removing RigidBody from the camera and moving it inside the camera stand prim in the Stage.

What I am doing wrong?

I’m using Isaac Sim 5.1.0.

[PeterL-NV]

Hi, Here're some possible causes that you can check:

1. Make sure both the camera and stand have RigidBodyAPI applied.
2. If the camera is part of another articulation, you may need to exclude the joint:

joint_prim.GetAttribute("physics:excludeFromArticulation").Set(True)

[arambarricalvoj]

Hi Peter,

I found where the problem was. The joint must be created between RSD455 and JoinedCameraStand2 (see attached image). However, I would like to understand why.

I was creating the joint between Realsense and JoinedCameraStand2, but Realsense is not a RigidBody and won't let me add it. Why? What type of object is Realsense? How is it defined in its .usd to give this behavior, i.e., that Realsense does not allow RigidBody to be added, but its subprim RSD455 does?

[PeterL-NV]

Hi, The Realsense prim is typically an Xform (transform) type that serves as a container/parent prim, while RSD455 (the actual camera model) is a UsdGeom.Gprim type.

According to USD's rigid body physics rules, RigidBodyAPI can only be applied to UsdGeom.Gprim types (geometry primitives like Sphere, Cube, etc.)