Help with launch of 2 robots

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Hi.

I'm new, but getting there...

I'm trying to spawn 2 robots in gazebo using ros

1. A robot controlled using joystick - package: joy
2. A "Compass" pointer robot controlled by a I2C compass

All code is available here: Git rep - For easy overview

I use 3 launch files - 1 to start and launch the other 2

Launch command: roslaunch mybot_gazebo start2.launch

I get this error and cannot find the error:

(Complete terminal launch and error output is available in the Readme.md in the git rep)

[ERROR] [1568837262.438582681]: Could not find parameter robot_description on parameter server
[compass/robot_state_publisher1-8] process has died [pid 14585, exit code 255, cmd /opt/ros/melodic/lib/robot_state_publisher/robot_state_publisher /joint_states:=/compass/joint_states __name:=robot_state_publisher1 __log:=/home/thr/.ros/log/9acdfe50-da37-11e9-a0b0-00044b8c64bc/compass-robot_state_publisher1-8.log].
log file: /home/thr/.ros/log/9acdfe50-da37-11e9-a0b0-00044b8c64bc/compass-robot_state_publisher1-8*.log

System:

• Nvidia Jetson TX2
• Ubuntu 18.04
• Ros Melodic
• Gazebo v9.0.0

Main launch file:

 <launch>
  <param name="/use_sim_time" value="true" />

    <include file="$(find gazebo_ros)/launch/empty_world.launch">
                <arg name="world_name" value="$(find mybot_gazebo)/worlds/mybot1.world"/>
                <arg name="gui" value="true"/>
    </include>

  <!-- include our robots -->
  <include file="$(find mybot_gazebo)/launch/mybot_twoPc.launch"/>
  </launch>

Robot/Compass launch file:

<launch>      

<group ns="nanobot">
    <param name="robot_description" command="$(find xacro)/xacro.py '$(find mybot_description)/urdf/mybot.xacro'" />
    <node name="mybot_spawn" pkg="gazebo_ros" type="spawn_model" output="screen" args="-urdf -param robot_description -model mybot" />
    <include file="$(find mybot_control)/launch/mybot_control.launch" />
</group>
<group ns="compass">
    <param name="compass_description" command="$(find xacro)/xacro.py '$(find mybot_description)/urdf/compass.xacro'" />
    <node name="compass_spawn" pkg="gazebo_ros" type="spawn_model" output="screen" args="-urdf -param compass_description -model compass" />
    <include file="$(find mybot_control)/launch/compass_control.launch" />
</group>

</launch>