Random number in launch file

asked 2015-08-21 05:06:44 -0500

niall
47 ●4 ●5 ●10

Hi all,

I'm using ROS Indigo with Gazebo to simulate a robot and I would like to spawn my robot at random positions in the world. I use launch files to start the whole simulation. In these launch files the spawning position is initially defined. Therefore I thought it would be best to create a random position in the launch file but since this is all xml, I doubt this is possible. Does anyone have any idea how I can somehow change the spawning position each run? Somehow run an external C++ program that passes a random number to the launch file?

Cheers

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answered 2015-08-21 13:55:44 -0500

NEngelhard
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updated 2022-01-27 08:24:46 -0500

lucasw

8729 ●137 ●239 ●256 https://github.com/lucasw

You could use a script to generate random ros parameters. Just include something like

<param name="robot_position" command="$(find some_package)/scripts/generate_random_position.py"/>

and the generate_random_position.py just returns a random position.

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Great Idea! That way I don't have to alter my normal launch procedure, just put this script before the spawn robot. Thanks FooBar!

niall ( 2015-08-24 10:33:43 -0500 )edit

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Hi @NEngelhard @niall, may I know what are the contents in the "generate_random_position.py" file? Is "robot_position" a 2d vector?

Jason-Zhou1 ( 2020-11-01 22:43:20 -0500 )edit

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reference the python script this link https://campus-rover.gitbook.io/lab-n...

hyunoklee ( 2022-01-05 08:12:45 -0500 )edit

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answered 2015-08-21 06:25:41 -0500

Stefan Kohlbrecher

24361 ●173 ●299 ●444 https://www.energy-rob...

One straightforward option is to start the launch file once, but use the gazebo_ros_pkgs service API to just move the model around as described in the "Set Model State Example" here. You could write a small Python node that calls this service with some random pose whenever you require it.

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