Simulation support on robotic sysytems with closed-loop constraints

Does Isaac Gym or the underlying simulation support robotic systems with closed-loop constraints defined by mechanisms (not the ground contact constraints)? Such as Delta manipulator robot or legged robots with closed-loop mechanism (passive springs etc). Thank you

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Unfortunately, we don’t currently have a way to specify closed loop constraints in Isaac Gym. Such constraints are supported by the physics engines themselves, but we just don’t have an API that exposes that currently.

One workaround could be to try and use fixed tendons or you could try to manually apply forces to enforce the constraints, though that’s not likely to be very stable because it happens outside of the solver.

The positive news is that we already do support closed loop constraints in Omni Gym, but it’s not released yet.

Thank you very much!

You are right, it would be best to link this feature from Omni to the Isaac Gym, rather than calculating the forces outside the solver. May I know any release plans for adding this feature and API into the Isaac Gym? Thank you!

Can you provide any pointer to the support of closed-loop constraints in Omni Gym? Thanks!

Any updates on the closed-loop constraint support?

Summary for the closed-loop link compatibility
URDF/MJCF: No native support. → Requires additional constraints
Isaac Sim/USD: Native support doc.

However, it appears that constraints and .usd are not supported in Isaac Gym yet?

Hello @lwawrzyniak, since it is two years later now, I would like to know if there is some more news about the closed kinematic loops? Is there now an option that would enable such closed kinematic loop robots in IsaacGym?

Also what is the mentioned Omni Gym about? What is the difference between Isaac Gym and Omni Gym?

Thank you kindly for your response,

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