No module named control_msgs.msg

edit

hello professors, when I try to use roslaunch command to run the robot, I found some problems that I can't solve it. The error shows that as followed :

Traceback (most recent call last):
File "/home/user/ros_workspace/arbotix/arbotix_python/nodes/driver.py", line 39, in <module>
from arbotix_python.follow_controller import FollowController
File "/home/user/ros_workspace/arbotix/arbotix_python/src/arbotix_python/follow_controller.py", line 32, in <module>
from control_msgs.msg import FollowJointTrajectoryAction
ImportError: No module named control_msgs.msg
[arbotix-1] process has died [pid 12272, exit code 1, cmd /home/user/ros_workspace/arbotix/arbotix_python/nodes/driver.py __name:=arbotix __log:=/home/user/.ros/log/dc7aa468-8815-11e3-98ad-ac72896c0c64/arbotix-1.log].
log file: /home/user/.ros/log/dc7aa468-8815-11e3-98ad-ac72896c0c64/arbotix-1*.log

I try to find control_msgs.msg on the internet, but I can't find it, if you have some information about this, please help me. Thanks again for your time.

And my launch file is as followed:

<launch>  
    <param name="/use_sim_time" value="false" />  

    <!-- Load the URDF/Xacro model of our robot -->  
    <arg name="urdf_file" default="$(find xacro)/xacro.py '$(find smartcar_description)/urdf/smartcar.urdf.xacro'" />  
    <arg name="gui" default="false" />  

    <param name="robot_description" command="$(arg urdf_file)" />  
    <param name="use_gui" value="$(arg gui)"/>  

    <node name="arbotix" pkg="arbotix_python" type="driver.py" output="screen">  
        <rosparam file="$(find smartcar_description)/config/smartcar_arbotix.yaml" command="load" />  
        <param name="sim" value="true"/>  
    </node>  

    <node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" >  
    </node>  

    <node name="robot_state_publisher" pkg="robot_state_publisher" type="state_publisher">  
        <param name="publish_frequency" type="double" value="20.0" />  
    </node>  

     <!-- We need a static transforms for the wheels -->  
    <node pkg="tf" type="static_transform_publisher" name="odom_left_wheel_broadcaster" args="0 0 0 0 0 0 /base_link /left_front_link 100" />  
    <node pkg="tf" type="static_transform_publisher" name="odom_right_wheel_broadcaster" args="0 0 0 0 0 0 /base_link /right_front_link 100" />  

    <node name="rviz" pkg="rviz" type="rviz" args="-d $(find smartcar_description)/urdf.vcg" />  
</launch>