Controlling Gazebo Cessna Plane with ROS

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Hi there, I was having the same challenge and I figure a solution for this problem. I know the post is old but it may give some clues for someone having the same troubles.

So first, the C++ file where the libCessnaPlugin.so comes from does not use any instance of ROS. It does mention that publishes the Pose and subscribes the motor speed but no through a ROS network since this files doesn't call anything from there. So I found this repo (https://github.com/AurelienRoy/ardupi...), where there is a plugin called aircraft_plugin which in essence is the same as the cessna_plugin but now this one does make use of a ROS node and subscribes to a topic called motor_message. This topic used the message CommandMotorSpeed that comes from the mav_com_mav_msgs package (I got it from here https://github.com/PX4/mav_comm).

Now, I tried to catkin_make the aircraftplugin and found several error due to deprecated fucntions of Gazebo since I was using Gazebo 9, and this plugin is old, so I had to change the old functions with the replacements base on this post (https://github.com/osrf/gazebo/blob/g...) and then I has able to compile the package.

Now, in order to attach the plugin to the Cessna model I added these lines in the URDF:

  <gazebo>
     <plugin name="aircraft_plugin" filename="libaircraft_plugin.so">
        <commandSubTopic>/command/motor_speed</commandSubTopic>
        <left_aileron>left_aileron_joint</left_aileron>
        <left_flap>left_flap_joint</left_flap>
        <right_aileron>right_aileron_joint</right_aileron>
        <right_flap>right_flap_joint</right_flap>
        <elevators>elevators_joint</elevators>
        <rudder>rudder_joint</rudder>
        <propeller>propeller_joint</propeller>
        <propeller_link>propeller</propeller_link>
        <propeller_max_rpm>37500</propeller_max_rpm>
     </plugin>
  </gazebo>

Finally, it took me a while to know how to publish in the topic so I could move the aricraft control surfaces, and this format worked for me (For testing purposes)

rostopic pub -r 10 /command/motor_speed mav_msgs/CommandMotorSpeed '{motor_speed: [100, 100, 100, 100, 100]}'

I am still new on Gazebo ROS development, but at least this worked for me, so I don't know if there was an easier solution, but it worked for me.

Hope it helps.