Hello I have made a launch file here using namespaces which spawns two ur5 /robot1 and /robot2. I have defined sperate controllers.yaml file for each robot. But because of the separate namespaces they are controlled and moved asynchronously. I would like to move them in sync. For this task what sort of modifications I need to with regards to urdf, xacro, launch files and .yaml files. I have added a snippet here of my launch file and controllers.yaml file

<?xml version="1.0"?>
<launch>
  <arg name="robot_name"/>
  <arg name="limited" default="true"/>
  <arg name="paused" default="true"/>
  <arg name="gui" default="true"/>
  <arg name="debug" default="false" />
  <arg name="sim" default="true" />

  <!-- startup simulated world -->
  <include file="$(find gazebo_ros)/launch/empty_world.launch">
    <arg name="world_name" value="$(find ur5_launcher)/launch/initialize.world"/>
    <arg name="paused" value="$(arg paused)"/>
    <arg name="gui" value="$(arg gui)"/>
  </include>

  <!-- spawn the conveyor_belt in gazebo -->
  <node name="spawn_table" pkg="gazebo_ros" type="spawn_model" args="-file $(find ur5_notebook)/urdf/table.urdf -urdf -model table" />

  <group ns="robot1">
    <!-- <param name="tf_prefix" value="robot1_tf" /> -->
      <include file="$(find ur_gazebo)/launch/ur5.launch">
        <arg name="init_pose" value="-z 0.805 -y 0.0 -x 0.35
                  -J shoulder_pan_joint 1.5708
                  -J shoulder_lift_joint -1.5708
                  -J elbow_joint 0
                  -J wrist_1_joint 0
                  -J wrist_2_joint 1.5708
                  -J wrist_3_joint 0"/>
        <arg name="robot_name" value="robot1"/>

      </include>

      <include file="$(find ur_gazebo)/launch/ur5_gripper_controllers.launch" />
      <remap if="$(arg sim)" from="follow_joint_trajectory" to="arm_controller/follow_joint_trajectory"/>

  </group>

  <node pkg="ur5_notebook" type="fixed_tf_broadcaster.py" name="broadcaster_fixed" />
  <node pkg="ur5_notebook" type="fixed_tf_broadcaster2.py" name="broadcaster_fixed_2" />

  <group ns="robot2">

      <include file="$(find ur_gazebo)/launch/ur5_r2.launch">
        <arg name="init_pose" value="-z 0.805 -y 0.0 -x 0.35 
                  -J shoulder_pan_joint 1.5708
                  -J shoulder_lift_joint -1.5708
                  -J elbow_joint 0
                  -J wrist_1_joint 3.14159
                  -J wrist_2_joint -1.5708
                  -J wrist_3_joint 0 -unpause"/>
        <arg name="robot_name" value="robot2"/>

      </include>

      <remap if="$(arg sim)" from="follow_joint_trajectory" to="arm_controller/follow_joint_trajectory"/>
      <include file="$(find ur_gazebo)/launch/ur5_r2_gripper_controllers.launch" />

  </group>


</launch>

Controllers.yaml file The controllers.yaml is the same for the other robot i.e. each robot has its own individual controllers.yaml file

arm_controller:
  type: position_controllers/JointTrajectoryController
  joints:
     - shoulder_pan_joint
     - shoulder_lift_joint
     - elbow_joint
     - wrist_1_joint
     - wrist_2_joint
     - wrist_3_joint
  constraints:
    # Default is 0
    goal_time: 0.1
    # Default is 0.01
    stopped_velocity_tolerance: 0.01
    shoulder_pan_joint:
      trajectory: 0
      goal: 0.01
    shoulder_lift_joint:
      trajectory: 0
      goal: 0.01
    elbow_joint:
      trajectory: 0
      goal: 0.01
    wrist_1_joint:
      trajectory: 0
      goal: 0.01
    wrist_2_joint:
      trajectory: 0
      goal: 0.01
    wrist_3_joint:
      trajectory: 0
      goal: 0.01 

  state_publish_rate: 100
  action_monitor_rate: 20