Unexpected Robot Movement in Environment with SDF-based Collision and Fixed Joints

Hello everyone,

I wanted to report a problem that I encountered while working with a setup involving a robot with fixed joints and approximated collision using SDF (Signed Distance Fields). In my environment, I added objects with fixed joints, similar to the robot, using SDF-based collision approximation. However, in some environments in parallel, as shown in the following pictures, the robot unexpectedly teleports to strange positions. I am using the Docker image of IsaacSim2022.2.1.

Interestingly, when I exclude the fixed joints from the SDF-based objects, the robot moves correctly, leading me to suspect that adding multiple fixed joints within a single environment triggers this bug. However, I noticed that in the Factory demo, bolt is able to have fixed joints without issues.

I’m seeking guidance on how to address this problem. Is there a recommended approach for adding multiple fixed joints within an environment that uses SDF-based collision? Any insights or suggestions would be greatly appreciated.

Thank you in advance for your help.

Best regards,

Here are the results when I executed the same implementation in IsaacSim 2022.2.0. The robot clearly spawned in an incorrect position.

Could this possibly be a bug or some issue related to the IsaacSim 2022 version?

In the above figures, I had set the pipeline to GPU for SDF simulation. As I mentioned before, when I switched the pipeline to CPU, the robot moved correctly, although SDF simulation was not possible. Is this an unresolved bug in the current version of IsaacSim? In the Factory demo, Franka operates properly even with the GPU pipeline, so there should be some solution available, but I’m not sure what it is. Could someone please help me with this issue?

Hi @makoto.sato385,

First, sorry for the very late reply. This could be a bug indeed. Would you be able to share a USD file with the repro above with us so we can have a look?

Thank you,