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I developed a node which represent an agent in an emergent system that implements a collision avoidance algorithm. Problem is, I need to perform multiple simulations with N robots, I know I can pass N as arg to launch file, but I can't find a way to launch N nodes in the launch file.
At the moment the only solution I have is to edit the launch file.
You could use eval (as of Kinetic) to create a recursive launchfile:
<launch>
<!-- start node -->
<arg name="nr" default="1"/>
<group ns="$(eval 'turtle' + str(arg('nr')))">
<node name="turtle" pkg="turtlesim" type="turtlesim_node"/>
</group>
<!-- recursively start new node -->
<include file="$(find your_package)/launch/this_launch_file.launch" if="$(eval arg('nr') - 1 > 0)">
<arg name="nr" value="$(eval arg('nr') - 1)"/>
</include>
</launch>
As of Lunar you could also use $(dirname) instead of $(find your_package)/launch.
I'm sorry, but I fail to understand how this is recursive? I tried this script by setting nr:=5 and it just launched the turtlesim node and my launch file once each.
hey cgnarendiran. are you sure you set the 'this_launch_file.launch' correctly? the name must be same as your desired launch file. For example, if you have an example.launch file and want to launch it 5 times, you should set the nr=5 as the default. Then you should re-launch your example.launch file in part. Include the example.launch file in that part by writing it's package, path and name correctly. This should work.
I am not aware of a way to launch N instances of the node by passing N as a roslaunch parameter, however you can follow the approach given here : put the section of the roslaunch file that you want to replicate inside a namespace ns tag, and pass the value of this namespace as a command line argument. Then you can have a shell script that calls your roslaunch command (e.g roslaunch youbot_gazebo youbot_gazebo ns:=/robot$i ) in a loop, each time with a different namespace value.
As far as I found out, there is no way to do it with a launch file. I solved it by writing a simple python program using the roslaunch API ( http://wiki.ros.org/roslaunch/API%20U... )
Thank you so so so much for this, this solved a problem we were facing for quite a while!
Asked: 2016-03-18 10:38:58 -0500
Seen: 5,165 times
Last updated: Apr 26 '18
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