Closed Chain Robot In Isaac Sim?

Omniverse Isaac Sim
1

Hi, I am very excited to see Isaac Gym is integrated. Thanks for your effort!

To my knowledge, currently Isaac Gym does not support creating closed chain mechanisms (like Delta Robot below) since the body relationship does not form a tree structure.
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I am not familar with Isaac Sim, but may I know whether Isaac Sim supports simulating this kind of robot?

Thanks in advance!

2

Hi Alan,

You should be able to simulate closed chain mechanism, have you tried to import the model into Isaac Sim?

3

The articulation API doesn’t support close loop chains, and articulation API is what you are probably using to solve for actuation. To make it work for, you’ll have to “break” the chain. Or in another word, leave some joints just as plain simple joints, and not articulation joints, so they are not in the articulation tree.

To delete articulation api from a joint, select the joint on the stage tree, and scroll down in its property panel, and simply x out the menu item that has to do with articulations.

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4

Thanks a lot! I will try that

5

Thanks very much for your information!

6

Have you succeedded? Could you give some solutions?

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7

Hi, I can confirm that close-chain mechanism can be simulated in Isaac Sim, but you have to modify the USD file such as excluding the un-actuated joints from articulation. I recently test the sim-to-real transfer, and the result is acceptable, so there should be no problem simulating close-chain (but you should increase the position/velocity solver iteration or decrease physics_dt to ensure a good sim-to-real performance).

You can also check this post: Support Parallel Robots?

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