Why are topics remapped when used with controllers?

Question

Hi all,

When using the UR5 package from ROS industrial, there is a python script called test_move.py which is used to generate a joint trajectory fed to the controllers. When this script is used remapping is used hence the command line for this script is the following:

./test_move.py follow_joint_trajectory:=arm_controller/follow_joint_trajectory

I have noticed that topics are often remapped when used with controllers. Is there any specific reason why?

Thanks,

Antoine.

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Originally posted by arennuit on ROS Answers with karma: 955 on 2015-02-09

Post score: 0

Answer 1

The somewhat obvious reason would be: Because the script and the controller don't use the same action namespace. Why they don't use the same name is somewhat guess work that the creators can answer. One reason might be that there is not standard/default name and "it just happened".

For arm controllers a reason could be that a standard name isn't possible because there might be multi-arm robots, e.g. left and right. In that case I'd prefer a simple name like just follow_joint_trajectory to remap from.

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Originally posted by dornhege with karma: 31395 on 2015-02-09

This answer was ACCEPTED on the original site

Post score: 1

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Original comments

Comment by arennuit on 2015-02-09:
Hum... It feels to me you are on the right track when you say it makes it possible to address different controllers with the same script. Thanks!