# Meaning of fields in the move_base\goal message

Hello,
I am sending move_base goal messages, but am having a hard time understanding what the different elements in the message mean (position + orientation). What is the 0,0 point in the map? How do I set the goal position fields in a meaningful way? Could you explain these or point me to a relevant tutorial ?

Thank you!

Hello @sarah.e.keren,

The position (0,0,0) is the center of the map, expressed in the (x,y,z) axis. So, for instance, assuming that you are at the (0,0,0) position, if you set a goal which is (1,0,0), this will make the robot move 1 meter in the x axis. As for the orientation, it refers to the “direction” the robot will be looking at.

The orientation is a bit more complex because it is expressed in quaternions. You can have a look at the following example, for instance, which explains how to convert from quaternion to euler angles: https://www.theconstructsim.com/ros-qa-how-to-convert-quaternions-to-euler-angles/. It might help you understand better how it works.

Hope this helps,