Unitree A1 apply action with joint positions does not work after respawn and world reset

Omniverse Isaac Sim
1

Hello,

I am spawning the Unitree A1 multiple times (sequentially, not in parallel) and therefore resetting the world.
Applying actions via ArticulationAction on the Unitree A1 works fine with joint torques after respawning the robot. But doing the same with joint positions does not work after respawning the robot. It only works for the first spawn. I also set the gains properly.

I tested on 2022.1.1, 2022.2.1

Thanks in advance.

2

Hi @fatih.oezgan

For position control, make sure to set relatively high stiffness and low damping values for the joint drives you want to command.

Chech the Articulation.apply_action description for more details

3

Thanks for the reply. The issue is not with the stiffness and damping, because i set those and apply_action also works with position values, but once i reset the world, so that the Unitree A1 is spawned again, apply action does not work anymore. This is not the case for applying joint efforts. With joint efforts, apply_action works despite resetting the world.