virtual_obstacles

This repository holds the virtual_obstcales packages for ROS Turtlebots. For more information see package.xml file. For license see LICENSE and the sourcecode.

This package needs more documentation and more work to be generic useful. I'll try to add more documentation and modify the source to be more flexible, but don't hold your breath. If you think it might be useful just ask and I'll try to help.

getting started

The moving_objects_msg_generator.py generates moving_object messages from Turtlebots position and planned routes and publishes them. The moving_objects.cpp is a Costmap Plugin and adds a obstacle layer to move_base so the route planner avoids the track of other robots and other robots even if they can't be seen by sensors.

To get it work this package has to be in your catkin workspace and compile without error on every robot and your coordniating ROS PC, then the move_base Package should be able to load this plugin.

Prerequirements

• every robot in its own namespace. (/Turtlebo1/, /Turtlebot2/, ...)
• working tf transformation between frame /map and all robots frames /TurtlebotX/base_footprint
• all ROS PCs use the same /map topic

Config change on every robot

To load the plugin you have to load different parameter sets in move_base.

So on every robots config you need to change the move_base node config like this:

<launch>
...
  <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">
    ...
    <!-- we comment out the turtlebot local_costmap params and use our own -->
    <!--<rosparam file="$(find turtlebot_navigation)/param/local_costmap_params.yaml" command="load" />-->
    <rosparam file="$(find virtual_obstacles)/param/local_costmap_params.yaml" command="load" />
    ...
    <!-- do the same for global_costmap params, here we our move_base plugin -->
    <!--<rosparam file="$(find turtlebot_navigation)/param/global_costmap_params.yaml" command="load" />-->
    <rosparam file="$(find virtual_obstacles)/param/global_costmap_params.yaml" command="load" />
    ...
  </node>
</launch>

Note: parameter in the yaml file have to be adjusted to your map and robots config.

Note: config of plugins parameters is possible over dynamic reconfigure.

Note: if own_unique_name is empty (default) namespace is used

Note: robot footprint is hardcoded to a radius of 0.2 m

Config change on coordinating workstation (i.e. roscore PC)

On a workstation PC you have to run moving_objects_generator by adding

<launch>
  ...
  <node name="moving_objects_msg_generator" pkg="virtual_obstacles" type="moving_objects_msg_generator.py" args="" />
  ...
</launch>

to your config or by simply running roslaunch virtual_obstacles moving_objects_generator.

Note: you may have to edit some strings in virtual_obstacles/src/moving_objects_msg_generator.py to match your namespaces and tf frame_id's to work.

Note: robot_names and unique_name in general means the name of the robots namespace.

In the end ....

In the end you should have a node moving_objects_msg_generator with one publisher and number of robots subscriber. And on every single robot a move_base node with loaded virtual_obstacles plug-in.