Joint between different namespace/models

edit

Hello,

I'm working on a project where I have to connect two quads on a bar. On the images below you can see what I have achieved so far.

https://ibb.co/fm511Q

https://ibb.co/khbVvk

I'd like to know if there's a way to create joints between the models on the image. The models have to be independent because I have to be able to fly the quads, and to do that they have to have different namespaces.

My launch file looks like this:

<?xml version="1.0"?>

<launch>


  <include file="$(find hector_gazebo_worlds)/launch/start.launch"/>


  <group ns="uav1">
     <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
       <arg name="name" value="uav1" />
       <arg name="tf_prefix" value="uav1" />
       <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor.gazebo.xacro" />
       <arg name="y" value="-1.0" />
       <arg name="controllers" value="
        controller/attitude
        controller/velocity
        controller/position
       "/>
     </include>
    <include file="$(find hector_quadrotor_teleop)/launch/taranis.launch" >
            <arg name="control_mode" value="velocity"/>
    </include>

  </group>

  <group ns="uav2">
     <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
       <arg name="name" value="uav2" />
       <arg name="tf_prefix" value="uav2" />
       <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor.gazebo.xacro" />
       <arg name="y" value="1.0" />
       <arg name="controllers" value="
        controller/attitude
        controller/velocity
        controller/position
       "/>
     </include>
    <include file="$(find hector_quadrotor_teleop)/launch/taranis.launch" >
            <arg name="control_mode" value="velocity"/>
    </include>

  </group>

  <group ns="barra">
     <include file="$(find hector_quadrotor_gazebo)/launch/spawn_barra.launch">
       <arg name="name" value="barra" />
       <arg name="y" value="0" />
     </include>

  </group>
</launch>

Thanks in advance, Pedro