I've successfully downloaded the packages for youbots in a new catkin workspace I created. I was also able to get it up and running and open in gazebo but I don't know where to start with the launch files to simply control the arms or get a few commands working. For example this is what one of the launch files looks like, found at $~/youbotdirws/src/youbotsimulation/youbotgazebocontrol/launch$ gedit armcontroller.launch, where youbotdirws is the workspace I created for this project:

?xml version="1.0"?

launch

arg name="armname" default="arm1"/

!-- upload arm and gripper controller parameters -- rosparam file="$(find youbotgazebocontrol)/config/$(arg armname)controller.yaml" command="load" ns="$(arg arm_name)"/

!-- spawn arm controller --> <node pkg="controllermanager" type="spawner" name="$(arg armname)armcontrollerspawner" args="$(arg armname)/arm_controller" respawn="false" output="screen" /

!-- spawn gripper controller --> <node pkg="controllermanager" type="spawner" name="$(arg armname)grippercontrollerspawner" args="$(arg armname)/gripper_controller" respawn="false" output="screen" /

/launch>` <arg name="armname" default="arm1"/

!-- upload arm and gripper controller parameters -- rosparam file="$(find youbotgazebocontrol)/config/$(arg armname)controller.yaml" command="load" ns="$(arg arm_name)"/

!-- spawn arm controller -- <node pkg="controllermanager" type="spawner" name="$(arg armname)armcontrollerspawner" args="$(arg armname)/arm_controller" respawn="false" output="screen" /

!-- spawn gripper controller -- node pkg="controllermanager" type="spawner" name="$(arg armname)grippercontrollerspawner" args="$(arg armname)/gripper_controller" respawn="false" output="screen" /

/launch