Skip to content

URDF

URDF is an xml file that describe the geometry of a robot. URDF is a tree structure with one root link. The measuring units are meters and radians.

robot
1
2
3
4
5
6
<robot name="robot_name">
  <link>  </link>
  <link>  </link>

  <joint>  </joint>
</robot>

The link element describes a rigid body with an inertia, visual features, and collision properties.

alt text

Tip

The reference frame of the link is its joint

link
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
<link name="link_name">

  <visual>
      <origin xyz="0 0 0" rpy="0 0 0" />
      <geometry>
        <cylinder length="0.6" radius="0.2"/>
      </geometry>
  </visual>

  <collision>
      <origin xyz="0 0 0" rpy="0 0 0" />
      <geometry>
          <cylinder length="0.6" radius="0.2"/>
      </geometry>
  </collision>

  <inertial>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <mass value="1"/>
      <inertia
          ixx="1.0" ixy="0.0" ixz="0.0"
          iyy="1.0" iyz="0.0"
          izz="1.0"/>
  </inertial>
</link>