Mesh-Mesh Collision Problems

Hi!

I was trying to simulate the collision between a teapot and a can. I run the simulation for about 30 time-steps but the objects don't collide with each other. However, the can and the teapot do collide with the plane. I checked the conaffinity and contype parameters, which should be correctly set. https://github.com/google/brax/assets/64325659/2d27afea-670c-4d2e-b865-1403590943c7

The relevant XML file is:

<mujoco model="ur5">
  <compiler angle="radian" autolimits="true"/>
  <statistic meansize="0.173315" extent="1.0834" center="0.408334 0.0869587 0.0891592"/>

  <default>
    <joint armature='0.04' damping="1" limited="true"/>
    <geom friction=".8 .1 .1" density="300" margin="0.002" condim="1" contype="0" conaffinity="0"/>
  </default>

  <option gravity="0 0 -9.81" timestep="0.01" iterations="4" />

  <asset>
      <include file="incl/table_assets.xml"/>
      <include file="incl/robot_assets.xml"/>
      <include file="incl/object_assets.xml"/>
  </asset>

  <worldbody>
      <light diffuse=".5 .5 .5" pos="0 0 3" dir="0 0 -1"/>
      <geom conaffinity="1" condim="3" friction="1 .1 .1" material="MatGnd2" name="floor" pos="0 0 0" size="20 20 0.125" type="plane"/>
      <include file="incl/robot.xml"/>
      <include file="incl/object.xml"/>

      <body name="teapot" pos="4 0 0.15">
        <geom name="teapot" pos="0 0 0" type="mesh" contype="1" mesh="teapot"/>
        <joint armature="0" damping="0" limited="false" margin="0.01" name="teapot" pos="0 0 0" type="free"/>
      </body>

      <body name="can" pos="4 0 0.08">
        <geom name="can" pos="0 0 0" type="mesh" contype="1" conaffinity="1" mesh="can"/>
        <joint armature="0" damping="0" limited="false" margin="0.01" name="can" pos="0 0 0" type="free"/>
      </body>
  </worldbody>

  <include file="incl/actuators.xml"/>

</mujoco>

To load this model, I use this script.

Another problem that I encountered when trying to load two bodies with <geom type="mesh"> is that the simulation freezes and it starts consuming a lot of resources. It freezes at:

I0117 12:04:46.256506 8010682368 mesh.py:242] Converting mesh (-5009138114913360041, 1111321369098598208) into convex hull.
I0117 12:04:46.807301 8010682368 mesh.py:242] Converting mesh (-3756864523981354566, 795501625399689805) into convex hull.
I0117 12:04:46.840853 8010682368 xla_bridge.py:660] Unable to initialize backend 'cuda': 
I0117 12:04:46.840950 8010682368 xla_bridge.py:660] Unable to initialize backend 'rocm': module 'jaxlib.xla_extension' has no attribute 'GpuAllocatorConfig'
I0117 12:04:46.841929 8010682368 xla_bridge.py:660] Unable to initialize backend 'tpu': INTERNAL: Failed to open libtpu.so: dlopen(libtpu.so, 0x0001): tried: 'libtpu.so' (no such file), '/System/Volumes/Preboot/Cryptexes/OSlibtpu.so' (no such file), '/Users/usr/miniconda3/bin/../lib/libtpu.so' (no such file), '/usr/lib/libtpu.so' (no such file, not in dyld cache), 'libtpu.so' (no such file), '/usr/local/lib/libtpu.so' (no such file), '/usr/lib/libtpu.so' (no such file, not in dyld cache)

This happens only when I try to simulate these bodies using the visualizer.py script. In order for me to visualize more than one body with <geom type="mesh"> I need to use the HTML tool provided. Why can't I load them using the visualizer.py script? The XML I used is:

<mujoco model="teapot_can">
  <compiler angle="degree" coordinate="local" inertiafromgeom="true"/>
  <option gravity="0 0 -9.81" timestep="0.01" iterations="4" integrator="Euler" />
  <custom>
  </custom>
  <default>
    <joint armature='0.04' damping="1" limited="true"/>
    <geom friction="1 .1 .1" density="300" margin="0.002" condim="6" contype="0" conaffinity="0"/>

  </default>
  <asset>
    <texture builtin="gradient" height="100" rgb1="1 1 1" rgb2="0 0 0" type="skybox" width="100"/>
    <texture builtin="flat" height="1278" mark="cross" markrgb="1 1 1" name="texgeom" random="0.01" rgb1="0.8 0.6 0.4" rgb2="0.8 0.6 0.4" type="cube" width="127"/>
    <texture builtin="checker" height="100" name="texplane" rgb1="0 0 0" rgb2="0.8 0.8 0.8" type="2d" width="100"/>
    <material name="MatPlane" reflectance="0.5" shininess="1" specular="1" texrepeat="60 60" texture="texplane"/>
    <material name="geom" texture="texgeom" texuniform="true"/>
    <mesh name="teapot" file="stl/utahteapot.stl" scale="0.1 0.1 0.1"/>
    <mesh name="can" file="obj/tomato_soup_can.obj" scale="5 5 5"/>
  </asset>
  <worldbody>
    <light cutoff="100" diffuse="1 1 1" dir="-0 0 -1.3" directional="true" exponent="1" pos="0 0 1.3" specular=".1 .1 .1"/>
    <geom conaffinity="1" condim="3" material="MatPlane" name="floor" pos="0 0 0" size="40 40 40" type="plane"/>
    <body name="teapot" pos="2 0 0.75">
      <geom name="teapot" pos="0 0 0" type="mesh" contype="1" mesh="teapot"/>
      <joint armature="0" damping="0" limited="false" margin="0.01" name="teapot" pos="0 0 0" type="free"/>
    </body>

    <body name="can" pos="0 0 0.2">
      <geom name="can" pos="0 0 0" type="mesh" contype="1" conaffinity="1" mesh="can"/>
      <joint armature="0" damping="0" limited="false" margin="0.01" name="can" pos="0 0 0" type="free"/>
    </body>
  </worldbody>
  <actuator>
  </actuator>
</mujoco>

If I comment out any of the two bodies, the simulation works without any problems.

Thank you in advance for your help!

google / brax

Mesh-Mesh Collision Problems #441