Object don't move through hole in other object #1174

DimaRubyAI · 2023-11-08T11:53:45Z

DimaRubyAI
Nov 8, 2023

I'm trying to understand what wrong with my scene,
I download a free object from here:
brake disk
after small changes that I made in blender I convert it to xml by:
obj2mjcf and used this object in Mujoco-Tutorial.
What I am trying to do is as follows:
Brake disk fall straight in the middle where pole (long and narrow cylinder) located.
I expect that the cylinder go through the disk's hole, but in contrast to that, the disk does not allow penetration through it, as if there is no hole in it.

checkerboard.mp4

what wrong here?
please let me know if some of the code required to answer this question.

mujoco version: 3.0.0

yuvaltassa · 2023-11-09T01:54:10Z

yuvaltassa
Nov 9, 2023
Maintainer

You need to decompose your mesh into convex pieces. CoACD Is quite good for this.

4 replies

DimaRubyAI Nov 9, 2023
Author

Thanks you,
I have tried to use CoACD in the process (before obj2mjcf), with the following parameters:
coacd -t 0.002 -c 2000
But still getting similar result..

checkerboard.mp4

Is there any other reason why this could happen?

erez-tom Nov 9, 2023
Collaborator

You should visualize the contact meshes which are calculated as the convex hull of the mesh files in the model (the key "h" IIRC).

DimaRubyAI Nov 13, 2023
Author

Thank you, but I'm not sure that I understand what should I do and what I have tried not really working..
I would appreciate it if you have a link with an example or a tutorial of about it.

DimaRubyAI Nov 15, 2023
Author

@yuvaltassa, can you please reopen the question or you want me to open a new issue ticket?

quagla · 2023-11-09T13:53:14Z

quagla
Nov 9, 2023
Collaborator

Another option would be to use the Signed Distance Function plugin https://mujoco.readthedocs.io/en/latest/programming/extension.html#exwriting but it is not available via Python.

2 replies

erez-tom Nov 9, 2023
Collaborator

https://github.com/google-deepmind/mujoco/blob/main/plugin/sdf/README.md

DimaRubyAI Nov 13, 2023
Author

If it is possible at this point I would be happy to stay in Python environment.

DimaRubyAI · 2023-11-13T12:35:50Z

DimaRubyAI
Nov 13, 2023
Author

I tried to use official cow example with some small changes (),

second cow remove
scale of torus
partial scale and position of cow1

<mujoco>
  <compiler texturedir="asset"/>

  <extension>
    <plugin plugin="mujoco.sdf.torus">
      <instance name="torus">
        <config key="radius1" value="0.15"/>
        <config key="radius2" value="0.05"/>
      </instance>
    </plugin>
    <plugin plugin="mujoco.sdf.sdflib">
      <instance name="sdf">
        <config key="aabb" value="0"/>
      </instance>
    </plugin>
  </extension>

  <asset>
    <texture name="texspot" type="2d" file="spot.png"/>
    <material name="matspot" texture="texspot"/>
    <mesh name="spot" file="asset/spot.obj" scale = "1 2 1">
      <plugin instance="sdf"/>
    </mesh>
    <mesh name="torus" scale = "10 10 10">
      <plugin instance="torus"/>
    </mesh>
  </asset>

  <option sdf_iterations="20" sdf_initpoints="40"/>

  <visual>
    <map force="1000"/>
  </visual>

  <default>
    <geom solref="0.01 1" solimp=".95 .99 .0001" friction="0.5"/>
  </default>

  <statistic meansize="0.2"/>

  <include file="scene.xml"/>

  <worldbody>
    <body pos="0.1 .25 5.7">
      <freejoint/>
      <geom type="sdf" mesh="torus" rgba=".2 .8 .2 1">
        <plugin instance="torus"/>
      </geom>
    </body>
    <body euler="90 0 0" pos="0 0 1.4">
      <geom type="sdf" name="cow1" mesh="spot" material="matspot">
        <plugin instance="sdf"/>
      </geom>
    </body>
    <light name="left" pos="0 0 1"/>
    <light name="right" pos="1 0 1"/>
  </worldbody>
</mujoco>

The result is similar to what was seen in the original question

Screen.Recording.2023-11-13.at.14.22.11.mov

What am I doing wrong?

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Object don't move through hole in other object #1174

DimaRubyAI Nov 8, 2023

Replies: 3 comments · 6 replies

yuvaltassa Nov 9, 2023 Maintainer

DimaRubyAI Nov 9, 2023 Author

erez-tom Nov 9, 2023 Collaborator

DimaRubyAI Nov 13, 2023 Author

DimaRubyAI Nov 15, 2023 Author

quagla Nov 9, 2023 Collaborator

erez-tom Nov 9, 2023 Collaborator

DimaRubyAI Nov 13, 2023 Author

DimaRubyAI Nov 13, 2023 Author

DimaRubyAI
Nov 8, 2023

Replies: 3 comments 6 replies

yuvaltassa
Nov 9, 2023
Maintainer

DimaRubyAI Nov 9, 2023
Author

erez-tom Nov 9, 2023
Collaborator

DimaRubyAI Nov 13, 2023
Author

DimaRubyAI Nov 15, 2023
Author

quagla
Nov 9, 2023
Collaborator

erez-tom Nov 9, 2023
Collaborator

DimaRubyAI Nov 13, 2023
Author

DimaRubyAI
Nov 13, 2023
Author