re-use model in SDF file, more than name and pose

Question

I'm trying to write a world by reusing models as much as I can. The world contains 2 similar models "PublicBathroomA" and "PublicBathroomB".
They differ in few things, pose and name which can be easily be changed with the corresponding sub-tags of , and with a link which differ only by its pose.

<model name="PublicBathroomA">
  <pose>
    9.0 3.0 0
    0 0 0
  </pose>
  ...
  <link name="door">
    <pose>-0.3 -0.05 0 0 0 6.07</pose>
    ...
  </link>
</model>

and

<model name="PublicBathroomB">
  <pose>
    12.0 3.0 0
    0 0 0
  </pose>
  ...
  <link name="door">
    <pose>-0.3 -0.05 0 0 0 6.17</pose>
    ...
  </link>
</model>

Do you have an idea on how to manage this link pose ? For the moment, my incomplete solution could be

    <include>
      <uri>model://office/PublicBathroom.sdf</uri>
      <name>PublicBathroomA</name>
      <pose>
        9.0 3.0 0
        0 0 0
      </pose>
    </include>

a working solution can be to generate on the fly the PublicBathroomA.sdf and PublicBathroomB.sdf files from a template and include both files, but it is not the same approach.

Answer 1

If you're in a ROS-aware environment or can install it separately, you might look at using xacro. Then you can define a xacro:macro.

For example (saving the content below as bathroom.sdf.xacro):

<?xml version="1.0"?>
<sdf version="1.11">
<world xmlns:xacro="http://www.ros.org/wiki/xacro">

<!-- Define the xacro:macro for later use -->
<xacro:macro name="public_bathroom" params="identifier=DEFAULT_ID pose='0 0 0 0 0 0' door_link_pose='0 0 0 0 0 0'">
<include>
  <model name="PublicBathroom${identifier}">
    <pose>
      ${pose}
    </pose>
    <sometag>
    </sometag>
    <link name="door">
      <pose>
        ${door_link_pose}
      </pose>
    </link>
  </model>
</include>
</xacro:macro>

<!-- Instantiate three different public bathrooms, the last one default -->
<xacro:public_bathroom identifier="A" pose="9.0 3.0 0 0 0 0" door_link_pose="-0.3 -0.05 0 0 0 6.07"/>
<xacro:public_bathroom identifier="B" pose="12.0 3.0 0 0 0 0" door_link_pose="-0.3 -0.05 0 0 0 6.17"/>
<xacro:public_bathroom/>

</world>
</sdf>

<sometag></sometag> is your common content across all bathrooms.

Running xacro bathroom.sdf.xacro results in this output:

<?xml version="1.0" ?>
<!-- =================================================================================== -->
<!-- |    This document was autogenerated by xacro from bathroom.sdf.xacro             | -->
<!-- |    EDITING THIS FILE BY HAND IS NOT RECOMMENDED                                 | -->
<!-- =================================================================================== -->
<sdf version="1.11">
  <world>
    <include>
      <model name="PublicBathroomA">
        <pose>
      9.0 3.0 0 0 0 0
    </pose>
        <sometag>
    </sometag>
        <link name="door">
          <pose>
        -0.3 -0.05 0 0 0 6.07
      </pose>
        </link>
      </model>
    </include>
    <include>
      <model name="PublicBathroomB">
        <pose>
      12.0 3.0 0 0 0 0
    </pose>
        <sometag>
    </sometag>
        <link name="door">
          <pose>
        -0.3 -0.05 0 0 0 6.17
      </pose>
        </link>
      </model>
    </include>
    <include>
      <model name="PublicBathroomDEFAULT_ID">
        <pose>
      0 0 0 0 0 0
    </pose>
        <sometag>
    </sometag>
        <link name="door">
          <pose>
        0 0 0 0 0 0
      </pose>
        </link>
      </model>
    </include>
  </world>
</sdf>

I don't know the details of installing xacro without ROS and the limitations there.

It seems like there are a couple of relevant recent PRs to allow xacro to work without ROS, but I haven't tried it:

https://github.com/ros/xacro/pull/329 https://github.com/ros/xacro/pull/340

I ran my example from a ROS 2 Humble environment.