Reviewing Configuration Data

Isaac Lab Configuration

In this module, we’ll review the process of configuring a robot inside Isaac Sim, to match settings used during training of a policy. In the next module, we’ll actually perform this conversion.

To simplify the course, the provided USD has all the joints rigged except for the left elbow joint, which we will do together as an example. In a realistic example, all joints would need configuration.

Isaac Lab Configuration Data

Let’s take a closer look at the configuration YAML data as it was defined in Isaac Lab, during the policy training done outside of this course.

We will look closely at the left_elbow joint and how to set up the physics for it.

Joint Positions

     joint_pos:
        .*_hip_yaw: 0.0
        .*_hip_roll: 0.0
        .*_hip_pitch: -0.28
        .*_knee: 0.79
        .*_ankle: -0.52
        torso: 0.0
        .*_shoulder_pitch: 0.28
        .*_shoulder_roll: 0.0
        .*_shoulder_yaw: 0.0
        .*_elbow: 0.52
      joint_vel:
        .*: 0.0

Joint Properties

     arms:
       class_type: omni.isaac.lab.actuators.actuator_pd:ImplicitActuator
       joint_names_expr:
       - .*_shoulder_pitch
       - .*_shoulder_roll
       - .*_shoulder_yaw
       - .*_elbow
       effort_limit: 300
       velocity_limit: 100.0
       stiffness:
         .*_shoulder_pitch: 40.0
         .*_shoulder_roll: 40.0
         .*_shoulder_yaw: 40.0
         .*_elbow: 40.0
       damping:
         .*_shoulder_pitch: 10.0
         .*_shoulder_roll: 10.0
         .*_shoulder_yaw: 10.0
         .*_elbow: 10.0
       armature: null
       friction: null

Converting the Parameters

Now to use these same parameters inside Isaac Sim, there’s a conversion process. For any angular definitions, we need to first convert these from radians to degrees.

Isaac Sim’s definition of these parameters is based on USD, which uses degrees instead of radians. The below values have been converted for you.

We’ll apply this data in the next module.

	Start Position	Effort Limit	Velocity Limit	Stiffness	Damping
Isaac Lab	0.52 rad	300 (Nm)	100 (rad/s)	40 (kgm^2/(rad s^2))	10 (kgm^2/(rad s))
Isaac Sim (These are the ones we use in this step)	29.79 deg	300 (Nm)	5729.58 (deg/s)	0.698132 (kgm^2/(deg s^2))	0.174533 (kgm^2/(deg s))