I think the problem is that you did not remap robot_description for the state publisher. In mybot_twoPc.launch you load the URDF inside compass_description, then include the file compass_control.launch (from pkg mybot_control). In there, you load again the URDF in compass_description (it is not necessary, but it does not cause any trouble) and finally start robot_state_publisher1. By default, such node assumes to find the robot description into robot_description. Since you use another name, you should change it to be:
<node name="robot_state_publisher1" pkg="robot_state_publisher" type="robot_state_publisher" respawn="false" output="screen">