urdf Documentation

urdf

This package contains a C++ parser for the Unified Robot Description Format (URDF), which is an XML format for representing a robot model. The code API of the parser has been through our review process and will remain backwards compatible in future releases.

• Homepage: http://wiki.ros.org/urdf

urdf::Model is a class containing robot model data structure. Every Robot Description File (URDF) can be described as a list of Links (urdf::Model::links_) and Joints (urdf::Model::joints_). The connection between links(nodes) and joints(edges) should define a tree (i.e. 1 parent link, 0+ children links).

• Here is an example Robot Description Describing a Parent Link 'P', a Child Link 'C', and a Joint 'J'

    <joint name="J" type="revolute">
      <dynamics damping="1" friction="0"/>
      <limit lower="0.9" upper="2.1" effort="1000" velocity="1"/>
      <safety_controller soft_lower_limit="0.7" soft_upper_limit="2.1" k_position="1" k_velocity="1" />
      <calibration reference_position="0.7" />
      <mimic joint="J100" offset="0" multiplier="0.7" />
  
      <!-- origin: origin of the joint in the parent frame -->
      <!-- child link frame is the joint frame -->
      <!-- axis is in the joint frame -->
      <origin xyz="0 0 0" rpy="0 0 0"/> 
      <axis xyz="0 1 0"/> 
      <parent link="P"/>
      <child link="C"/>
    </joint>
  
    <link name="C">
      <inertial>
        <mass value="10"/>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <inertia ixx="1" ixy="0" ixz="0" iyy="1" iyz="0" izz="1"/>
      </inertial>
  
      <visual>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
          <box size="1 1 1"/>
        </geometry>
        <material name="Green"/>
      </visual>
  
      <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
          <box size="1.01 1.01 1.01"/>
        </geometry>
        <contact_coefficient mu="0"  resitution="0"  k_p="0"  k_d="0" />
      </collision>
    </link>
  
    <material name="Green">
      <texture filename="...texture file..." />
      <!--color rgb="255 255 255" /-->
    </material>
   

codeapi

The URDF parser API contains the following methods:

• Parse and build tree from XML: urdf::Model::initXml
• Parse and build tree from File: urdf::Model::initFile
• Parse and build tree from String: urdf::Model::initString
• Get Root Link: urdf::Model::getRoot
• Get Link by name urdf::Model::getLink
• Get all Link's urdf::Model::getLinks
• Get Joint by name urdf::Model::getJoint