i want to know urdf creating trand for robots ?

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I'm new for Ros and gazebo am working to simulate double Ackermann steering robot Ros melodic but am having hard time creating urdf file ,i already done with the tutorials I can do basic things but am wondering is it obvious creating urdf by Ros tutorial or is it done in cad software most of the time .....and am planning to add slam for autonomy .am working alone and am planning to finish in the two month is it achievable for new user , I highly appreciate any advice .