How to enable/add some components in husky.urdf.xacro?

[alhaddad-m]

Greetings!
I need to add some components to husky robot such as UR5 manipulation and sensor_arch to husky.urdf.xacro.
Actually I have used husky_manipulation and husky packages and when I added the next line to husky.urdf.xacro:
<xacro:include filename="$(find husky_ur_description)/urdf/husky_ur5_description.urdf.xacro" />
the manipulation has been appeared with robot as following in gazebo:
roslaunch husky_gazebo husky_empty_world.launch

and to enable sensor_arch component, the husky.urdf.xacro already includes it in
<xacro:include filename="$(find husky_description)/urdf/accessories/sensor_arch.urdf.xacro"/>
and I have enabled it in <xacro:arg name="realsense_enabled" default="true" /> but it doesn't appear in gazebo. Could you give me solution? and sorry for this dummy question.
Please note that I need to launch the robotic complex in gazebo.

[civerachb-cpr]

I just ran

roslaunch husky_gazebo husky_empty_world.launch realsense_enabled:=true

and the sensor arch with RealSense D435 appeared as-expected. Setting HUSKY_URDF_EXTRAS to point to the husky_ur5_description.urdf.xacro from husky_manipulation and rulling the above command gives the robot with the arm & sensor arch present:

Can you please share the output you're seeing in the terminal when you launch gazebo?

[alhaddad-m]

@civerachb-cpr Thank for reply. Actually, the problem was that value of realsense_enabled in launch file is overriding its value in urdf.xacro file i.e. I have made its value "true" in urdf file while its value in launch file was "false" so when I launched the file, it took the value from launch file and considered that realsense_enabled is false.
Could you please explain why I have to set HUSKY_URDF_EXTRAS (and how) even though I have made the changes that I need.

[civerachb-cpr]

<xacro:arg name="realsense_enabled" default="false" /> appears multiple times across the launch files. Depending where you changed the default from false to true may be contributing to the problem.

If you only changed the default in spawn_husky.launch then the sensor bar will not appear when launching the empty world. If you look at husky_empty_world.launch you'll see that launch file has its own realsense_enabled argument, which is passed directly to spawn_husky.launch which would override the default:

husky_empty_world.launch:

<arg name="laser_enabled" default="true"/>
<arg name="realsense_enabled" default="false"/>
[...]
<include file="$(find husky_gazebo)/launch/spawn_husky.launch">
    <arg name="laser_enabled" value="$(arg laser_enabled)"/>
    <arg name="realsense_enabled" value="$(arg realsense_enabled)"/>
</include>

You'll likely also want to set laser_enabled to false as otherwise a Sick LMS1xx will spawn on Husky's front_mount link, which you can see in both of our screenshots above (it's the black object clipping through the base joint of the arm).

Could you please explain why I have to set HUSKY_URDF_EXTRAS (and how) even though I have made the changes that I need.

If you have already modified the Husky URDF as necessary you do not need to set the HUSKY_URDF_EXTRAS environment variable. That variable is just a utility we provide to make customizing the Husky easier. The way to set it is to add the line

export HUSKY_URDF_EXTRAS=/path/to/extras.urdf.xacro

to your bash setup. On a physical robot this is normally done in /etc/ros/setup.bash. On a desktop where you're working in Gazebo you could add it to $HOME/.bashrc or to /opt/ros/melodic/setup.bash.

This is optional, and if you've already modified the URDF file to add the arm (as it appears you have) then don't worry about the URDF extras variable.

[alhaddad-m]

Thank you.