Wiki example with PR2 not working

[Cryptum169]

Hi! I ran into some errors when parsing PR2 urdf files, and it seems the example from wiki http://wiki.ros.org/urdfdom_py is not working for me as well.

> rosrun urdfdom_py display_urdf `rospack find pr2_mechanism_model`/pr2.urdf

Unknown attribute "type" in /robot[@name='pr2']/link[@name='base_laser_link']
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='fl_caster_rotation_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='fr_caster_rotation_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='bl_caster_rotation_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='br_caster_rotation_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='torso_lift_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='head_pan_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='head_tilt_joint']/calibration
Unknown attribute "type" in /robot[@name='pr2']/link[@name='wide_stereo_optical_frame']
Unknown attribute "type" in /robot[@name='pr2']/link[@name='narrow_stereo_optical_frame']
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='laser_tilt_mount_joint']/calibration
Unknown attribute "type" in /robot[@name='pr2']/link[@name='laser_tilt_link']
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='r_shoulder_pan_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='r_shoulder_lift_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='r_upper_arm_roll_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='r_forearm_roll_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='r_elbow_flex_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='r_wrist_flex_joint']/calibration
Unknown attribute "reference_position" in /robot[@name='pr2']/joint[@name='r_wrist_roll_joint']/calibration
Unknown tag "verbose" in /robot[@name='pr2']/link[@name='r_wrist_roll_link']/collision[1]
Traceback (most recent call last):
  File "/home/perceptron/catkin_ws_calib/devel/lib/urdfdom_py/display_urdf", line 15, in <module>
    exec(compile(fh.read(), python_script, 'exec'), context)
  File "/home/perceptron/catkin_ws_calib/src/urdf_parser_py/scripts/display_urdf", line 18, in <module>
    robot = URDF.from_xml_string(args.file.read())
  File "/home/perceptron/catkin_ws_calib/src/urdf_parser_py/src/urdf_parser_py/xml_reflection/core.py", line 616, in from_xml_string
    return cls.from_xml(node, path)
  File "/home/perceptron/catkin_ws_calib/src/urdf_parser_py/src/urdf_parser_py/xml_reflection/core.py", line 610, in from_xml
    return cur_type.from_xml(node, path)
  File "/home/perceptron/catkin_ws_calib/src/urdf_parser_py/src/urdf_parser_py/xml_reflection/core.py", line 232, in from_xml
    obj.read_xml(node, path)
  File "/home/perceptron/catkin_ws_calib/src/urdf_parser_py/src/urdf_parser_py/xml_reflection/core.py", line 598, in read_xml
    self.XML_REFL.set_from_xml(self, node, path)
  File "/home/perceptron/catkin_ws_calib/src/urdf_parser_py/src/urdf_parser_py/xml_reflection/core.py", line 513, in set_from_xml
    element.add_from_xml(obj, child, element_path)
  File "/home/perceptron/catkin_ws_calib/src/urdf_parser_py/src/urdf_parser_py/xml_reflection/core.py", line 390, in add_from_xml
    value = self.value_type.from_xml(node, path)
  File "/home/perceptron/catkin_ws_calib/src/urdf_parser_py/src/urdf_parser_py/xml_reflection/core.py", line 283, in from_xml
    raise ParseError(Exception(out), path)
urdf_parser_py.xml_reflection.core.ParseError: ParseError in /robot[@name='pr2']/transmission[@name='r_wrist_trans']:
Could not perform duck-typed parsing.
Value Type: <class 'urdf_parser_py.urdf.Transmission'>
Exception: ParseError in /robot[@name='pr2']/transmission[@name='r_wrist_trans']:
Required element not set in XML: type

This seems to be an instance of #36 and ros/urdfdom#36 (comment) but I'm not sure why the fix in that issue didn't help with this, any help or pointer is appreciated!