How to use mocap after ​​setting​​ random joint angles.

[Hellcat1005]

Intro

Hi!

I am a researcher at Naton, I use MuJoCo for my research on imitative learning.

My setup

Version: 3.3.1
API: Python

My question

I randomly initialize the joint angles of the robotic arm through code and command it to move to that pose. I then intend to control the robotic arm using motion capture (MoCap) to perform my task. However, I noticed that when the following code is added, the robotic arm fails to reach the specified joint angles, whereas it works correctly without the code.

<equality> <weld body1="mocap" body2="load"/> </equality>

The angles I set:

Use mocap after setting angles:

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.

[Balint-H]

Could you clarify a couple things for me:

Are you saying that setting the qpos is ignored completely if you have the equality enabled? Or does it still go to the specified state, then rapidly change to resolve the equality constraint? If the second, then it is behaving as intended. Can you explain what you expected to happen and how you intend to use the mocap body and the weld constraint?

Please have a look at the weld constraint's documentation if you haven't yet: https://mujoco.readthedocs.io/en/stable/XMLreference.html#equality-weld

It sounds like you'd like to do some kind of inverse kinematics based control. If that is the case, I can't recommend anything better then the tools provided by mink.