Sorry for my insistent questions but , I really couldnt made correctly this tutorial , when I edit my_robot.urdf file and given even a description (as xml ) into it but I could not rosrun it when I

rosrun check_urdf my_robot.urdf

there is the terminal error is this :

atilay@atilayLnxPC:~$ rosrun urdfdom check_urdf my_robot.urdf
[rospack] Error: package 'urdfdom' not found

should i install urdfdom ? Because I have read that urdfdom is failing while with liburdfdom-tools

could anybody tell me what should I install for URDF Tutorials or making my robot urdf ? Also when I just command

check_urdf my_robot.urdf

there is sayin terminal to me that : atilay@atilayLnxPC:~$ checkurdf myrobot.urdf

Error:   Error document empty.
         at line 72 in /build/buildd/urdfdom-0.2.10+dfsg/urdf_parser/src/model.cpp
ERROR: Model Parsing the xml failed

what should I do ?