Add center of mass setter and getter for RigidObject

[yuecideng]

Description

• Add center of mass setter and getter for rigid object. Also add a randomization functor for this attribte.
• Add body type API for kinematic and dynamic exchanging.

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• I have run the black . command to format the code base.
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Dependencies have been updated, if applicable.

[Copilot]

Pull request overview

This PR adds center of mass (COM) getter and setter functionality for RigidObject, along with a randomization function to support domain randomization of COM properties.

Changes:

• Added com_pose property getter and default_com_pose storage to RigidBodyData class
• Added set_com_pose method to RigidObject class
• Added randomize_rigid_object_center_of_mass function to support COM randomization
• Updated type annotations from Union[torch.Tensor, List[int]] to torch.Tensor | list[int] for consistency

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
embodichain/lab/sim/objects/rigid_object.py	Adds COM data structures, property getter, and setter method to enable reading and modifying center of mass pose
embodichain/lab/gym/envs/managers/randomization/physics.py	Adds randomization function for COM and updates type annotations for consistency

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.