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Multiple turtlebots - real experiments

asked 2012-08-21 06:58:21 -0500

maurizio gravatar image

Hi,

I have a question related to multiple real turtlebots. I have to setup the system and I was wondering which is the best configuration for it.

In particular, I want to use two turtlebots and a work station at the same time, what should be the best configuration?

Basically each turtlebot should run its own navigation stack but I need to contact both the turtlebots through a single program residing on the workstation.

Is it possible to launch the roscore on the workstation and then launch each navigation stack onboard the related robot?
What about namespaces related to robots?

I had some problems with the simulated experiments but in the end we solved the problem (please look here)

Thank you

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answered 2012-08-21 12:05:29 -0500

Ryan gravatar image

Yes, it is possible to launch roscore on the workstation and then have the Turtlebots connect to them. As for namespacing, you'll want to do that in /etc/ros/electric/turtlebot.launch for the basic TurtleBot hardware, and again in each nav stack launcher (turtlebot_navigation/gmapping_demo.launch, etc).

There are also a few arguments in launchfiles which will need to be adjusted to work properly within namespaces. For instance, turtlebot_bringup/kinect.launch has a few topics which need to have the "/" prefix removed. You should also set tf_prefix within /etc/ros/electric/turtlebot.launch to your namespace:

<param name="tf_prefix" type="string" value="$(arg robot_id)" />

You could also create a static transformation between a global frame and each TurtleBot's global frame, just so every TurtleBot is "stock" within its namespace:

<node pkg="tf" type="static_transform_publisher" name="base_ref" args="0 0 0 0 0 0 /odom /$(arg robot_id)/odom 100" />

I hope this helps!

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Thank you Ryan. I will try in the next days. By the way, in last days I set up everything for simulating two turtlebots. It took a while since, as you said, I had to remove the "/" prefixes: do you think it would be useful to remove them permanently in the official release of ROS?

maurizio gravatar image maurizio  ( 2012-08-27 22:01:58 -0500 )edit

I am working with Electric and not with Fuerte so I am not aware if these problems were fixed in the last release. I had to tweak some configuration files, but do you see any problem to make them compliant for single and multi-robot experiments simply adding a namespace in the high level conf files?

maurizio gravatar image maurizio  ( 2012-08-27 22:07:55 -0500 )edit

@maurizio, did you manage to run multiple turtlebots under namespaces?

gavran gravatar image gavran  ( 2016-05-03 09:32:54 -0500 )edit
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answered 2012-08-21 08:20:04 -0500

updated 2012-08-21 08:20:57 -0500

Take a look at this http://answers.ros.org/question/41433/multiple-robots-simulation-and-navigation/">Answer it's more focused on simulation but it should help you also with real robots.

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Yes, thank you for the link. I was one of the guys involved and it took a lot to setup everything in simulation. In the next days I will try with the real ones

maurizio gravatar image maurizio  ( 2012-08-27 21:55:58 -0500 )edit

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Asked: 2012-08-21 06:58:21 -0500

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Last updated: Aug 21 '12