Gazebo couldn't find controller_manager

edit

I've been trying to control a gazebo simulation but this warning keep appering

Controller Spawner couldn't find the expected controller_manager ROS interface.

I was able to spawn my robot on gazebo and rviz before added on my urdf the gazebo_ros_control plugin and the transmissions ,so The problem must have been after that. I've added the libgazebo_ros_control like this:

<!-- ros_control plugin -->
<gazebo>
    <plugin name="gazebo_ros_control" filename="libgazebo_ros_control.so">
        <robotNamespace>/arm_robot</robotNamespace>
    </plugin>
</gazebo>

so on my spawner i've put the same namespace to match. like this:

<?xml version="1.0" encoding="UTF-8"?>
<launch>
    <include file="$(find gazebo_ros)/launch/empty_world.launch" />

    <param name="arm_description" command="cat $(find arm_description)/urdf/arm_description.urdf" />

    <node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="False" output="screen" args="-urdf -param arm_description -model arm_robot" />

    <!-- Load controllers -->  
    <rosparam command="load" file="$(find arm_description)/config/joints_controllers.yaml" />

    <!-- Controllers -->
    <node name="controller_spawner" pkg="controller_manager" type="spawner" respawn="false" output="screen" ns="/arm_robot" args="--namespace=/arm_robot
            joint_state_controller
            joint1_position_controller
            joint2_position_controller
            joint3_position_controller
            --timeout 60">
    </node>
</launch>

In another ROS Answer ( https://answers.ros.org/question/2147... ) and on gazebosim tutorial is said that the namespace is what gives the most trouble. honestly, I don't know how to move forward from this point.

my project is on https://github.com/DMPatod/industrial...