Renaming topics, parameters, services ...

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I have developed one robot software.

Now I want to launch 3 robots simultaneously and I am having problems because of the names. To differentiate the nodes of each robot I have used "ns" but it hasn't worked with the topics and parameters.

What I need is to use a prefix in topics name:

/robot1/topic_camera /robot2/topic_camera

Is there an easy way of doing this in the launch files? (remap is not an option)