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urdf Moveit articulation robot

asked 2014-12-03 03:47:44 -0500

ROSkinect gravatar image

I wanna ask you a simple question about where the articulation axis is defined ? or must be defined ? in 'stl' files or in urdf ?

image description

This is from my urdf file

<!-- =================================================================================== -->
<robot name="staubli_tx60">
  <link name="bt">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="file:///meshes/tx60/bt.stl"/>
      </geometry>
      <material name="">
        <color rgba="1.0 0.608 0 1"/>
      </material>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="file:///meshes/tx60/bt.stl"/>
      </geometry>
    </collision>
  </link>

  <joint name="joint_1" type="revolute">
    <origin rpy="0 0 0" xyz="0 0 0"/>
    <parent link="bt"/>
    <child link="at1"/>
    <axis xyz="0 0 1"/>
    <limit effort="0" lower="-2.967060" upper="2.967060" velocity="2.88"/>
  </joint>

  <link name="at1">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="file:///meshes/tx60/at1.stl"/>
      </geometry>
      <material name="">
        <color rgba="1.0 0.608 0 1"/>
      </material>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="file:///meshes/tx60/at1.stl"/>
      </geometry>
    </collision>
  </link>

  <joint name="joint_2" type="revolute">
    <parent link="at1"/>
    <child link="at2"/>
    <origin rpy="0 0 0" xyz="0 0 0"/>
    <axis xyz="0 1 0"/>
    <limit effort="0" lower="-2.4" upper="2.4" velocity="2.62"/>
  </joint>

  <link name="at2">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="file:///meshes/tx60/at2.stl"/>
      </geometry>
      <material name="">
        <color rgba="1.0 0.608 0 1"/>
      </material>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="file:///meshes/tx60/at2.stl"/>
      </geometry>
    </collision>
  </link>
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answered 2014-12-03 06:35:40 -0500

The meshes/stl files provide just the (rigid body) link geometry for a link of your robot and nothing more. Where a STL shows up of course depends on where the origin (i.e. 0/0/0 coords/axes) is located in the STL and where it is placed in the URDF using the <origin> element. The rotation axes are defined using the <axis> element inside a <joint>.

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yes this is what I need is how to look for the origin in the STL ? there is a software to do that ?

ROSkinect gravatar image ROSkinect  ( 2014-12-03 06:59:02 -0500 )edit
1

You can use Meshlab, Blender or a multitude of other 3D modeling/CAD programs for that. STL is about the most used mesh format, so many tools have support for it. If you want to change the origin, you'll have to find out how to do it with the tool of your choice though :)

Stefan Kohlbrecher gravatar image Stefan Kohlbrecher  ( 2014-12-03 07:41:41 -0500 )edit

I tried Meshlab but I get lost .. you know who to do that using either Meshlab or another one !!

ROSkinect gravatar image ROSkinect  ( 2014-12-03 10:41:58 -0500 )edit

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Asked: 2014-12-03 03:47:44 -0500

Seen: 262 times

Last updated: Dec 03 '14