Creating Custom Props

Creating Custom Props#

Learn how to create custom objects (props) for your tasks.

Prop Basics#

Props are objects in the environment (cubes, pots, books, etc.).

Available Props#

RoboEval includes many pre-built props:

  • Cube - Basic cube object

  • Table - Surface for placing objects

  • KitchenPot - Pot with handles

  • Book - Book object for stacking

  • Shelf - Bookshelf

  • Valve - Rotatable valve wheel

  • Box - Container for packing

  • Tray - Tray for carrying objects

Using Existing Props#

from roboeval.envs.props.items import Cube
from roboeval.envs.props.tables import Table

# In your task's _initialize_env method
self.table = Table(self._mojo)
self.cube = Cube(self._mojo)

# Position props using set_pose
self.cube.set_pose(position=np.array([0.5, 0.0, 1.0]))

Creating Custom Props#

Create a new prop class by inheriting from Prop or KinematicProp:

from pathlib import Path
from roboeval.envs.props.prop import KinematicProp
from roboeval.const import ASSETS_PATH

class MyCustomProp(KinematicProp):
    """My custom prop."""

    @property
    def _model_path(self) -> Path:
        """Path to the prop's XML/URDF model."""
        return ASSETS_PATH / "props/my_prop/my_prop.xml"

    def _on_loaded(self, model):
        """Optional: Customize prop after loading."""
        # Modify the model before it's finalized
        pass

    def _post_init(self):
        """Optional: Customize prop after initialization."""
        # Additional setup after prop is created
        pass

Prop vs KinematicProp:

  • Prop: Base class for all props (abstract)

  • KinematicProp: Kinematic collidable props (default for most objects) - Sets _KINEMATIC = True - Sets _CACHE_COLLIDERS = True - Use for objects that should collide and be manipulated

Using 3D Models#

Props can use URDF or MuJoCo XML models:

<!-- my_prop.xml -->
<mujoco>
  <worldbody>
    <body name="prop_body">
      <geom type="box" size="0.05 0.05 0.05"
            rgba="1 0 0 1" mass="0.1"/>
    </body>
  </worldbody>
</mujoco>

Best Practices#

  1. Use existing props when possible

  2. Keep collision meshes simple

  3. Set appropriate mass and inertia

  4. Add visual markers for grasping points

See Also#

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