Surface Gripper extension does not work on my gripper which was imported as stl file

Omniverse Isaac Sim
,
1

Isaac Sim Version

4.2.0

Operating System

Ubuntu 22.04

Topic Description

I try to use the surface gripper extension.

I tried to use it with omnigraph and it works great when I follow the tutorial with the two cubes.

But I fail to replicate this when I use my gripper which I imported from an .stl file

the gripper.usd has the following hierarchic:

gripper(xform)
-Visuals
--Material
-triangle(xform)
--triangle (mesh)
- --I’ve added the surface gripper here but also tried every other option like gripper(xform) or triangle (xform)

I’ve tried everything: from only using the triangle(mesh), adding rigid body and colliders preset to gripper(xform) and/or triangle(xform) and/or triangle(mesh).

How can I make it works it is so easy when I just use two cubes.
P.S. I also tried to add a cube to my gripper and just add the extension to the cube but then it doesn’t work anymore.

2

Hey, I am encountering the same problem.
Version
I’m using **Isaac Sim 4.5.0.
Gripper Hierarchy(imported stl model):

/World
  └── Gripper (Xform)
        ├── looks (Scope)
        │     └── DefaultMaterial (Material)
        │           └── DefaultMaterial (Shader)
        └── PARTassembly (Xform)
              └── PARTassembly (Mesh)

Error that I get:
I followed the documentation exactly, but when I try to send an impulse to close the gripper via the Action Graph, I get the following error in the console:

Parent rigid Body handle not valid for prim /World/Gripper/PARTassembly/PARTassembly

Terminal Output:

2025-04-08 13:35:26 [3,936,414ms] [Error] [omni.isaac.dynamic_control.plugin] Failed to register rigid body at '/World/Gripper/PARTassembly/PARTassembly'
2025-04-08 13:35:26 [3,936,415ms] [Error] [isaacsim.robot.surface_gripper.python] Parent rigid Body handle not valid for prim /World/Gripper/PARTassembly/PARTassembly
2025-04-08 13:35:26 [3,936,415ms] [Error] [omni.isaac.dynamic_control.plugin] Failed to register rigid body at '/World/Gripper/PARTassembly/PARTassembly'
2025-04-08 13:35:26 [3,936,415ms] [Error] [isaacsim.robot.surface_gripper.python] Parent rigid Body handle not valid for prim /World/Gripper/PARTassembly/PARTassembly
2025-04-08 13:35:26 [3,936,416ms] [Error] [omni.isaac.dynamic_control.plugin] Failed to register rigid body at '/World/Gripper/PARTassembly/PARTassembly'
2025-04-08 13:35:26 [3,936,416ms] [Error] [isaacsim.robot.surface_gripper.python] Parent rigid Body handle not valid for prim /World/Gripper/PARTassembly/PARTassembly
4

Hi @henry.hehl and @terence0tan, thank you for sharing this issue. I will look into this shortly.

5

Hi @michalin, I solved this issue by setting the PARTassembly mesh as the rigid body with collision. I used to set them for /World/Gripper but the Surface Gripper Action Graph only comes out with impulse_monitor and SurfaceGripperNode in the stage tree, no SurfaceGripperOffset.

1 Like
6

Great! Yes, you definitely want to make the prim that is used as Surface Gripper a Rigid Body.
@henry.hehl let me know if this fixes your issue as well.

7

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