Problems with xacro for MoveIt tutorials with ROS Kinect

edit

I am a beginner with ROS and I am facing Xacro problems while trying to follow the MoveIt Rviz Plugin Tutorial ( http://docs.ros.org/kinetic/api/movei... ). After setting up config files through the MoveIt Setup Assistant, when I try to run the command roslaunch pr2_moveit_config demo.launch, I got warnings which asked me to include the right xmlns:xacro definition ( http://www.ros.org/wiki/xacro ) which I also did. Simultaneously, Rviz would launch without the pr2 robot model (an error occurs as robot_description argument is not found. ) Following this, I get the following output for the command roslaunch pr2_moveit_config demo.launch,

NODES
  /
    joint_state_publisher (joint_state_publisher/joint_state_publisher)
    move_group (moveit_ros_move_group/move_group)
    robot_state_publisher (robot_state_publisher/robot_state_publisher)
    rviz_SalvationStorm_7296_6721935649591266222 (rviz/rviz)
    virtual_joint_broadcaster_0 (tf/static_transform_publisher)

auto-starting new master
process[master]: started with pid [7311]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to 093ca828-fc2d-11e6-b1c1-bc7737741913
process[rosout-1]: started with pid [7324]
started core service [/rosout]
process[virtual_joint_broadcaster_0-2]: started with pid [7341]
process[joint_state_publisher-3]: started with pid [7342]
process[robot_state_publisher-4]: started with pid [7353]
process[move_group-5]: started with pid [7354]
process[rviz_SalvationStorm_7296_6721935649591266222-6]: started with pid [7355]
[ WARN] [1488118110.883576885]: The root link base_footprint has an inertia specified in the URDF, but KDL does not support a root link with an inertia.  As a workaround, you can add an extra dummy link to your URDF.
[ INFO] [1488118111.008415902]: Loading robot model 'pr2'...
[ INFO] [1488118111.106837390]: rviz version 1.12.4
[ INFO] [1488118111.106915010]: compiled against Qt version 5.5.1
[ INFO] [1488118111.106933945]: compiled against OGRE version 1.9.0 (Ghadamon)
terminate called after throwing an instance of 'ros::InvalidNameException'
  what():  Character [ ] at element [16] is not valid in Graph Resource Name [/move_group/Left Arm/kinematics_solver].  Valid characters are a-z, A-Z, 0-9, / and _.
[ INFO] [1488118111.361866340]: Stereo is NOT SUPPORTED
[ INFO] [1488118111.362096155]: OpenGl version: 3 (GLSL 1.3).
[move_group-5] process has died [pid 7354, exit code -6, cmd /opt/ros/kinetic/lib/moveit_ros_move_group/move_group --debug __name:=move_group __log:=/home/vishnudev/.ros/log/093ca828-fc2d-11e6-b1c1-bc7737741913/move_group-5.log].
log file: /home/vishnudev/.ros/log/093ca828-fc2d-11e6-b1c1-bc7737741913/move_group-5*.log
[ INFO] [1488118115.215667344]: Loading robot model 'pr2'...
[ERROR] [1488118115.524969559]: Exception caught while processing action 'loadRobotModel': Character [ ] at element [50] is not valid in Graph Resource Name [/rviz_SalvationStorm_7296_6721935649591266222/Left Arm/kinematics_solver].  Valid characters are a-z, A-Z, 0-9, / and _.

At the same time, inside Rviz, I see that no planning library loaded. Under the motion planning category in the display tab, robot_description is set for ROBOT DESCRIPTION but no robot is displayed. I have tried the solutions that I could find while scouring the Internet, but was of no help, any suggestions?