UR5 industrial repo and setup assistant, certain questions

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Hi,

I am using MoveIt Setup Assistant (MSA), to create a set of initial configurations for manipulations with universal robots UR5 arm. For this purpose, I have followed this link that guides through the steps. We used ROS industrial repositories of UR5 downloaded from this link into my catkin_ws.

The initial step in the MSA step-by-step wizard requires a robot urdf model file, which I have used from ~/catkin_ws/src/universal_robot/ur_description/urdf.

1. The above location contains ur5_robot.urdf.xacro, and ur5.urdf.xacro. Is there any particular difference between the two?
2. The link states that

you can directly import XACRO files in addition to URDF files

however, I received the following error in MSA when using either of the xacro files. URDF/COLLADA file is not a valid robot model. Then, I used the following commands to create a urdf file from the give xacro files.

xacro --inorder ur5.urdf.xacro > p4_tmp.urdf && check_urdf p4_tmp.urdf

giving me errors as follows:

Error:   No name given for the robot.
         at line 89 in /build/urdfdom-YMMa9X/urdfdom-1.0.0/urdf_parser/src/model.cpp
ERROR: Model Parsing the xml failed

Finally, the following succeeds giving the urdf file that I can use with MSA.

xacro --inorder ur5_robot.urdf.xacro > p4_tmp.urdf && check_urdf p4_tmp.urdf

The same command generates link tree of the UR5 robotic arm.

root Link: world has 1 child(ren)
    child(1):  base_link
        child(1):  base
        child(2):  shoulder_link
            child(1):  upper_arm_link
                child(1):  forearm_link
                    child(1):  wrist_1_link
                        child(1):  wrist_2_link
                            child(1):  wrist_3_link
                                child(1):  ee_link
                                child(2):  tool0

• Next, when we need to create the virtual joint,

additional joints need to be defined to specify the pose of the root link on the robot with respect to a world coordinate system.

I am not certain how to assign values to different parts here. Is the following assignment correct.

Virtual Joinit Name: FixedBase
Child Link: world  (should match the URDF root link) 
Parent Frame Name: world
Type: fixed

thanks for help.

Zahid