Change in attach Behavior for Included Bodies in MuJoCo 3.2.6

[ValentinaGiannotti]

Intro

Hi!

I am a student at University of Federico II, I use MuJoCo for my research .

My setup

Mujoco 3.2.6

My question

In MuJoCo version 3.2.6, I’ve encountered an issue with body attachment when including a body defined in another file using the attach feature. In this version, the included body is automatically fixed to the world, whereas in version 3.2.3, the attach feature allowed the included body to remain an independent entity. Previously, adding a freejoint to the included body enabled free movement, but this approach no longer works in the latest version.

To address this, I’m considering merging all the code into a single file, which would restore the desired behavior. However, I’m seeking a more efficient and elegant solution. Is it possible to modify the XML structure or configure the included body differently to regain its independent functionality without having to consolidate everything into one file?

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]

Can you please add a minimal example that explains what you are describing? Your description is hard to follow. What happened before, what is happening now.