util_defs.xml

<?xml version="1.0"?>
<robot xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor"
       xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
       xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface">

  <property name="M_PI" value="3.1415926535897931"/>

  <!-- Little helper macro to define the inertia matrix needed for links. -->

  <macro name="cuboid_inertia_def" params="width height length mass">
    <inertia ixx="${mass * (height * height + length * length) / 12)}"
             iyy="${mass * (width * width + length * length) / 12)}"
             izz="${mass * (width * width + height * height) / 12)}"
             ixy="0" iyz="0" ixz="0"/>
  </macro>

  <!-- Length is along the y-axis. -->

  <macro name="cylinder_inertia_def" params="radius length mass">
    <inertia ixx="${mass * (3 * radius * radius + length * length) / 12)}"
             iyy="${mass * radius * radius / 2)}"
             izz="${mass * (3 * radius * radius + length * length) / 12)}"
             ixy="0" iyz="0" ixz="0"/>
  </macro>

  <macro name="sphere_inertia" params="radius mass">
    <inertial>
      <mass value="${mass}"/>
      <inertia ixx="${(2*mass*radius*radius)/5}"
               iyy="${(2*mass*radius*radius)/5}"
               izz="${(2*mass*radius*radius)/5}"
               ixy="0" iyz="0" ixz="0" />
      </inertial>
  </macro>

  <macro name="cuboid_inertia" params="width height length mass">
    <inertial>
      <mass value="${mass}"/>
      <cuboid_inertia_def width="${width}" height="${height}" length="${length}" mass="${mass}"/>
    </inertial>
  </macro>

  <macro name="cylinder_inertia" params="radius length mass">
    <inertial>
      <mass value="${mass}"/>
      <cylinder_inertia_def radius="${radius}" length="${length}" mass="${mass}"/>
    </inertial>
  </macro>

</robot>