URDF Importer

Omniverse Isaac Sim
1

Hi!

I’m trying to load the following urdf file (with the corresponding meshes in the seprate folder). I’ve adapted the file from urdf/Tutorials/Building a Visual Robot Model with URDF from Scratch - ROS Wiki a bit

<robot name="ROBOT">
<material name="blue">
    <color rgba="0 0 0.8 1"/>
  </material>
  <material name="black">
    <color rgba="0 0 0 1"/>
  </material>
  <material name="white">
    <color rgba="1 1 1 1"/>
  </material>

  <link name="base_link">
    <visual>
      <geometry>
        <cylinder length="0.6" radius="0.2"/>
      </geometry>
      <material name="blue"/>
    </visual>
  </link>

  <link name="right_leg">
    <visual>
      <geometry>
        <box size="0.6 0.1 0.2"/>
      </geometry>
      <origin rpy="0 1.57075 0" xyz="0 0 -0.3"/>
      <material name="white"/>
    </visual>
  </link>

  <joint name="base_to_right_leg" type="fixed">
    <parent link="base_link"/>
    <child link="right_leg"/>
    <origin xyz="0 -0.22 0.25"/>
  </joint>

  <link name="right_base">
    <visual>
      <geometry>
        <box size="0.4 0.1 0.1"/>
      </geometry>
      <material name="white"/>
    </visual>
  </link>

  <joint name="right_base_joint" type="fixed">
    <parent link="right_leg"/>
    <child link="right_base"/>
    <origin xyz="0 0 -0.6"/>
  </joint>

  <link name="right_front_wheel">
    <visual>
      <origin rpy="1.57075 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.1" radius="0.035"/>
      </geometry>
      <material name="black"/>
      <origin rpy="0 0 0" xyz="0 0 0"/>
    </visual>
  </link>
  <joint name="right_front_wheel_joint" type="fixed">
    <parent link="right_base"/>
    <child link="right_front_wheel"/>
    <origin rpy="0 0 0" xyz="0.133333333333 0 -0.085"/>
  </joint>

  <link name="right_back_wheel">
    <visual>
      <origin rpy="1.57075 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.1" radius="0.035"/>
      </geometry>
      <material name="black"/>
    </visual>
  </link>
  <joint name="right_back_wheel_joint" type="fixed">
    <parent link="right_base"/>
    <child link="right_back_wheel"/>
    <origin rpy="0 0 0" xyz="-0.133333333333 0 -0.085"/>
  </joint>

  <link name="left_leg">
    <visual>
      <geometry>
        <box size="0.6 0.1 0.2"/>
      </geometry>
      <origin rpy="0 1.57075 0" xyz="0 0 -0.3"/>
      <material name="white"/>
    </visual>
  </link>

  <joint name="base_to_left_leg" type="fixed">
    <parent link="base_link"/>
    <child link="left_leg"/>
    <origin xyz="0 0.22 0.25"/>
  </joint>

  <link name="left_base">
    <visual>
      <geometry>
        <box size="0.4 0.1 0.1"/>
      </geometry>
      <material name="white"/>
    </visual>
  </link>

  <joint name="left_base_joint" type="fixed">
    <parent link="left_leg"/>
    <child link="left_base"/>
    <origin xyz="0 0 -0.6"/>
  </joint>

  <link name="left_front_wheel">
    <visual>
      <origin rpy="1.57075 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.1" radius="0.035"/>
      </geometry>
      <material name="black"/>
    </visual>
  </link>
  <joint name="left_front_wheel_joint" type="fixed">
    <parent link="left_base"/>
    <child link="left_front_wheel"/>
    <origin rpy="0 0 0" xyz="0.133333333333 0 -0.085"/>
  </joint>

  <link name="left_back_wheel">
    <visual>
      <origin rpy="1.57075 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.1" radius="0.035"/>
      </geometry>
      <material name="black"/>
    </visual>
  </link>
  <joint name="left_back_wheel_joint" type="fixed">
    <parent link="left_base"/>
    <child link="left_back_wheel"/>
    <origin rpy="0 0 0" xyz="-0.133333333333 0 -0.085"/>
  </joint>

  <joint name="gripper_extension" type="fixed">
    <parent link="base_link"/>
    <child link="gripper_pole"/>
    <origin rpy="0 0 0" xyz="0.19 0 0.2"/>
  </joint>

  <link name="gripper_pole">
    <visual>
      <geometry>
        <cylinder length="0.2" radius="0.01"/>
      </geometry>
      <origin rpy="0 1.57075 0 " xyz="0.1 0 0"/>
    </visual>
  </link>

  <joint name="left_gripper_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0.2 0.01 0"/>
    <parent link="gripper_pole"/>
    <child link="left_gripper"/>
  </joint>

  <link name="left_gripper">
    <visual>
      <origin rpy="0.0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="../meshes/l_finger.dae"/>
      </geometry>
    </visual>
  </link>

  <joint name="left_tip_joint" type="fixed">
    <parent link="left_gripper"/>
    <child link="left_tip"/>
  </joint>

  <link name="left_tip">
    <visual>
      <origin rpy="0.0 0 0" xyz="0.09137 0.00495 0"/>
      <geometry>
        <mesh filename="../meshes/l_finger_tip.dae"/>
      </geometry>
    </visual>
  </link>
  <joint name="right_gripper_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0.2 -0.01 0"/>
    <parent link="gripper_pole"/>
    <child link="right_gripper"/>
  </joint>

  <link name="right_gripper">
    <visual>
      <origin rpy="-3.1415 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="../meshes/l_finger.dae"/>
      </geometry>
    </visual>
  </link>

  <joint name="right_tip_joint" type="fixed">
    <parent link="right_gripper"/>
    <child link="right_tip"/>
  </joint>

  <link name="right_tip">
    <visual>
      <origin rpy="-3.1415 0 0" xyz="0.09137 0.00495 0"/>
      <geometry>
        <mesh filename="../meshes/l_finger_tip.dae"/>
      </geometry>
    </visual>
  </link>

  <link name="head">
    <visual>
      <geometry>
        <sphere radius="0.2"/>
      </geometry>
      <material name="white"/>
    </visual>
  </link>
  <joint name="head_swivel" type="fixed">
    <parent link="base_link"/>
    <child link="head"/>
    <origin xyz="0 0 0.3"/>
  </joint>

  <link name="box">
    <visual>
      <geometry>
        <box size="0.08 0.08 0.08"/>
      </geometry>
      <material name="blue"/>
    </visual>
  </link>

  <joint name="tobox" type="fixed">
    <parent link="head"/>
    <child link="box"/>
    <origin xyz="0.1814 0 0.1414"/>
  </joint>
</robot>

But I do get the following Segmentation fault error from the running isaac sim container:

2020-10-16 11:35:44 [651,265ms] [Info] [omni.isaac.urdf] Trying to import /isaac-sim/_build/linux-x86_64/release/exts/omni.isaac.samples/omni/isaac/samples/scripts/urdf_examples/simple_robot/urdf/robot.urdf
[NvIsaac::Debug] Executable path: '/isaac-sim/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/omniverse-kit'
[NvIsaac::Debug] Found data directory '/isaac-sim/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/data'
[NvIsaac::Debug] Asset search paths:
[NvIsaac::Debug]   /isaac-sim
[NvIsaac::Debug]   /isaac-sim/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/data
[NvIsaac::Debug]   /isaac-sim/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/data/urdf
[NvIsaac::Debug]   /isaac-sim/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/data/IML
[NvIsaac::Debug]   /isaac-sim/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/data/cache
[NvIsaac::Debug]   /isaac-sim/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/data/commandscript
[NvIsaac::Debug]   /isaac-sim/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/data/meshes
[NvIsaac::Debug]   /isaac-sim/_build/target-deps/kit_sdk_release/_build/linux-x86_64/release/data/TestData
**[NvIsaac::Info] Stream Importing robot from '/isaac-sim/_build/linux-x86_64/release/exts/omni.isModel ROBOT loaded!**
Fatal Python error: Segmentation fault
Current thread 0x00007f07e0f31740 (most recent call first):
  File "/isaac-sim/_build/linux-x86_64/release/exts/omni.isaac.urdf/omni/isaac/urdf/scripts/extension.py", line 60 in _select_picked_folder_callback
/isaac-sim/_build/linux-x86_64/release/isaac-sim-headless.sh: line 4:    10 Segmentation fault      (core dumped) "$SCRIPT_DIR/../../target-deps/kit_sdk_release/_build/linux-x86_64/release/omniverse-kit" --config-path "$SCRIPT_DIR//experiences/isaac-sim-headless.json" --no-window $@

and then the client also freezes of course.

I even get the error with a simple file like:

<robot name="myfirst">
  <link name="base_link">
<visual>
  <geometry>
    <cylinder length="0.6" radius="0.2"/>
  </geometry>
</visual>
  </link>
</robot>

Any ideas?

2

Hi,

I have been doing some test and I have the next non-absolute and non-infallible empirical conclusion about the URDF importer that can be helpful

The URDF to be imported into Isaac-Sim must have at least one joint between two links and two links with their mass defined within an inertial tag

Notes

  • The mass defined inside the inertial tag have to be greater than zero, for example:
    <inertial>
    <mass value="0.001"/>
</inertial>

See the next examples based on your reference:

<?xml version="1.0"?>
<robot name="myfirst">
  <link name="world">
    <inertial>
      <mass value="0.001"/>
    </inertial>
  </link>
  <joint name="joint" type="fixed">
    <parent link="world"/>
    <child link="base_link"/>
  </joint>
  <link name="base_link">
    <inertial>
      <mass value="1"/>
    </inertial>
    <visual>
      <geometry>
        <cylinder length="0.6" radius="0.2"/>
      </geometry>
    </visual>
  </link>
</robot>

urdf
urdf1284×760 162 KB

<robot name="ROBOT">
<material name="blue">
    <color rgba="0 0 0.8 1"/>
  </material>
  <material name="black">
    <color rgba="0 0 0 1"/>
  </material>
  <material name="white">
    <color rgba="1 1 1 1"/>
  </material>

  <link name="base_link">
    <inertial>
      <mass value="0.001"/>
    </inertial>
    <visual>
      <geometry>
        <cylinder length="0.6" radius="0.2"/>
      </geometry>
      <material name="blue"/>
    </visual>
  </link>

  <link name="right_leg">
    <inertial>
      <mass value="0.001"/>
    </inertial>
    <visual>
      <geometry>
        <box size="0.6 0.1 0.2"/>
      </geometry>
      <origin rpy="0 1.57075 0" xyz="0 0 -0.3"/>
      <material name="white"/>
    </visual>
  </link>

  <joint name="base_to_right_leg" type="fixed">
    <parent link="base_link"/>
    <child link="right_leg"/>
    <origin xyz="0 -0.22 0.25"/>
  </joint>

  <link name="right_base">
    <visual>
      <geometry>
        <box size="0.4 0.1 0.1"/>
      </geometry>
      <material name="white"/>
    </visual>
  </link>

  <joint name="right_base_joint" type="fixed">
    <parent link="right_leg"/>
    <child link="right_base"/>
    <origin xyz="0 0 -0.6"/>
  </joint>

  <link name="right_front_wheel">
    <visual>
      <origin rpy="1.57075 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.1" radius="0.035"/>
      </geometry>
      <material name="black"/>
      <origin rpy="0 0 0" xyz="0 0 0"/>
    </visual>
  </link>
  <joint name="right_front_wheel_joint" type="fixed">
    <parent link="right_base"/>
    <child link="right_front_wheel"/>
    <origin rpy="0 0 0" xyz="0.133333333333 0 -0.085"/>
  </joint>

  <link name="right_back_wheel">
    <visual>
      <origin rpy="1.57075 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.1" radius="0.035"/>
      </geometry>
      <material name="black"/>
    </visual>
  </link>
  <joint name="right_back_wheel_joint" type="fixed">
    <parent link="right_base"/>
    <child link="right_back_wheel"/>
    <origin rpy="0 0 0" xyz="-0.133333333333 0 -0.085"/>
  </joint>

  <link name="left_leg">
    <visual>
      <geometry>
        <box size="0.6 0.1 0.2"/>
      </geometry>
      <origin rpy="0 1.57075 0" xyz="0 0 -0.3"/>
      <material name="white"/>
    </visual>
  </link>

  <joint name="base_to_left_leg" type="fixed">
    <parent link="base_link"/>
    <child link="left_leg"/>
    <origin xyz="0 0.22 0.25"/>
  </joint>

  <link name="left_base">
    <visual>
      <geometry>
        <box size="0.4 0.1 0.1"/>
      </geometry>
      <material name="white"/>
    </visual>
  </link>

  <joint name="left_base_joint" type="fixed">
    <parent link="left_leg"/>
    <child link="left_base"/>
    <origin xyz="0 0 -0.6"/>
  </joint>

  <link name="left_front_wheel">
    <visual>
      <origin rpy="1.57075 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.1" radius="0.035"/>
      </geometry>
      <material name="black"/>
    </visual>
  </link>
  <joint name="left_front_wheel_joint" type="fixed">
    <parent link="left_base"/>
    <child link="left_front_wheel"/>
    <origin rpy="0 0 0" xyz="0.133333333333 0 -0.085"/>
  </joint>

  <link name="left_back_wheel">
    <visual>
      <origin rpy="1.57075 0 0" xyz="0 0 0"/>
      <geometry>
        <cylinder length="0.1" radius="0.035"/>
      </geometry>
      <material name="black"/>
    </visual>
  </link>
  <joint name="left_back_wheel_joint" type="fixed">
    <parent link="left_base"/>
    <child link="left_back_wheel"/>
    <origin rpy="0 0 0" xyz="-0.133333333333 0 -0.085"/>
  </joint>

  <joint name="gripper_extension" type="fixed">
    <parent link="base_link"/>
    <child link="gripper_pole"/>
    <origin rpy="0 0 0" xyz="0.19 0 0.2"/>
  </joint>

  <link name="gripper_pole">
    <visual>
      <geometry>
        <cylinder length="0.2" radius="0.01"/>
      </geometry>
      <origin rpy="0 1.57075 0 " xyz="0.1 0 0"/>
    </visual>
  </link>

  <joint name="left_gripper_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0.2 0.01 0"/>
    <parent link="gripper_pole"/>
    <child link="left_gripper"/>
  </joint>

  <link name="left_gripper">
    <visual>
      <origin rpy="0.0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="../meshes/l_finger.dae"/>
      </geometry>
    </visual>
  </link>

  <joint name="left_tip_joint" type="fixed">
    <parent link="left_gripper"/>
    <child link="left_tip"/>
  </joint>

  <link name="left_tip">
    <visual>
      <origin rpy="0.0 0 0" xyz="0.09137 0.00495 0"/>
      <geometry>
        <mesh filename="../meshes/l_finger_tip.dae"/>
      </geometry>
    </visual>
  </link>
  <joint name="right_gripper_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0.2 -0.01 0"/>
    <parent link="gripper_pole"/>
    <child link="right_gripper"/>
  </joint>

  <link name="right_gripper">
    <visual>
      <origin rpy="-3.1415 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="../meshes/l_finger.dae"/>
      </geometry>
    </visual>
  </link>

  <joint name="right_tip_joint" type="fixed">
    <parent link="right_gripper"/>
    <child link="right_tip"/>
  </joint>

  <link name="right_tip">
    <visual>
      <origin rpy="-3.1415 0 0" xyz="0.09137 0.00495 0"/>
      <geometry>
        <mesh filename="../meshes/l_finger_tip.dae"/>
      </geometry>
    </visual>
  </link>

  <link name="head">
    <visual>
      <geometry>
        <sphere radius="0.2"/>
      </geometry>
      <material name="white"/>
    </visual>
  </link>
  <joint name="head_swivel" type="fixed">
    <parent link="base_link"/>
    <child link="head"/>
    <origin xyz="0 0 0.3"/>
  </joint>

  <link name="box">
    <visual>
      <geometry>
        <box size="0.08 0.08 0.08"/>
      </geometry>
      <material name="blue"/>
    </visual>
  </link>

  <joint name="tobox" type="fixed">
    <parent link="head"/>
    <child link="box"/>
    <origin xyz="0.1814 0 0.1414"/>
  </joint>
</robot>

urdf_1
urdf_11284×762 126 KB

1 Like
3

Sorry for the late reply! Thank you so much for your answer Toni. I’ll try it out later

4

I just hit this – for some reason the OnShape importer imported with no joints.

Feature request: Please add error messages when the urdf is invalid rather than segfaulting.