Get_velocities returns a vector filled with zeros in cartpole RL training

Omniverse Isaac Sim
1

I am trying to get the linear velocities of the end effector for my manipulator in a RL environment. My goal is to port the OSC controller from IsaacGym example to OmniIsaacGymEnv. But get_velocities returns a vector with zero velocities when running the cartpole example. However, when running the quadcopter example the vector returns actual numbers.
Is there a flag I am missing? Are the velocities with respect to local link frames? I am using the get_velocities method in ArticulationView.

Thank you!

3

Hi there, the get_velocities() API in ArticulationView will return the velocities for only the root body of the articulation. If you’d like to retrieve the velocities for the end effector links, you can use the RigidPrimView APIs to retrieve velocities for those bodies.