Not able to rotate revolute joints in isaac sim


I am trying to create a humanoid robot with few simple cylinder from scratch in isaac sim by following this. But while playing none of the joints are rotating and robot is falling apart. I have followed below steps:

  1. create xforms for all meshes.

  2. Added physics scene to the world

  3. Added Physics API for all cylindrical parts.

  4. Added fixed joint between body and world frame.

  5. Added revolute joints to all other joint positions.

  6. added Articulation API and drive API to all joints.

  7. Moved the joints to the particular location.

Please let me know what am I missing.

Please find the attached usd file and video of creating that usd file step by step.

Please help me here as I am stuck in this step for a long time to understand this.

Also, it will be really helpful if you can add creating a robot usd(not the objects but setting up overall stage with physics) in isaac sim from scratch in documentation of isaac sim.humanoid.usd (87.9 KB)

If the attached video link does not work please refer this.

1 Like

Added Physics api and mass api to all prime and collision api to all meshes and it worked.

HI Santu,

Glad to hear you figured it out.

Hi there,

I’m having a similar problem for controlling revolute joints in rigging a custom robot arm - I was able to make a single-joint example (test_joint.usd (24.5 KB) ) and control that successfully with the joint manipulation example notebook, with a modified kinematics JSON single_test.kinematic.json (420 Bytes) .

However, when I move onto rigging an imported STEP robotic arm (cr3.usd (2.3 MB) ) and setting up the joints, I can see the joint state being updated, and setting joint target within Isaac Omniverse works, but I cannot control the joint position from the notebook.

I’ve set physics and mass to each xform rigid body, collision to mesh, and articulated joint & drive for all the revolute joints, and the articulation root (fixed base). REB_joint_control is set to /World/Robot (the articulated prim for the joints), everything as detailed inside the rigging instructions - so I’m struggling to figure out the reason why one works over the other.

Duplicated question - see