How to get observations (Pose / velocity of geoms) in the Frame of reference of an agent?

[shantnavagarwal]

Intro

Hi!

I am a graduate student at TU Delft, I use MuJoCo for my research on Multi-agent Reinforcement Learning.

My setup

Mujoco: 3.2.5
MJX: 3.2.5 (Not being used)
Python: 3.10

My question

I have multiple agents within a single Mujoco environment. I am able to get values of any geom's pose and velocity in the world frame. I want to ask if there is a way to get these values in an agent's frame of reference.

One approach I have found is to get the agent's frame quaternion and pos from mj_data and then use functions from the Poses API. My question is: Is there a direct way to specify a body (via it's ID) and get values from mj_data in the body's frame?

Thanks!

Minimal model and/or code that explain my question

No response

Confirmations

• I searched the latest documentation thoroughly before posting.
• I searched previous Issues and Discussions, I am certain this has not been raised before.

[yuvaltassa]

This is most easily accomplished with sensors. All "framexx" sensors accept a reference frame object.

[shantnavagarwal]

Thanks for giving the correct reference. sensor/framepos