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Isaac Sim Version
[V ] 4.2.0
4.1.0
4.0.0
2023.1.1
2023.1.0-hotfix.1
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[V] Ubuntu 22.04
Ubuntu 20.04
Windows 11
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Topic Description
Detailed Description
I am working on my robot which legs are 4-bar links structure similar to digit and I aim to train it learn walking in Isaac lab. I read the document for Articulation and Close loops from Omniverse Extensions but still not understanding how to make such a mechanism and the setting correctly.
The step I try to do is:
1.Make robot’s URDF file
2.Import robot’s URDF into Isaac Sim to make the close-loop links and export as USD file
3.Use the USD file in Isaac lab to start training
My robot’s leg looks like below. Joint_A is driven by a motor and from joint_B to joint_D are all passive joints.
My question is:
1.Is it correct to make the relationship in urdf file as option (a) or option (b)?
(realtionship: parent → child)
(a)link_AB → link_AC → link_CD(with revolute joints A and C), Then import robot urdf and link_BD and add articulation at joint B and joint D in Isaac sim.
(b)link_AB → link_AC → link_CD ->link_DB(with revolute joints A,C,D). Then add articulation at joint B in Isaac sim.
2.The example mentioned in Close loop contents saying " we could tie the ragdoll’s hands together by adding a distance joint between the two hand spheres." It seems the close loop mechanism works without the force and torque information between those links in the last joint where we try to close the loop…?
- Is there any more detail about setting which is curcial to make close-loop links that need to be carefully handle with…?
If there are anybody has successfully making the close-loop links works or understanding the issue, I am really appreciate for your help!
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