[ros-users] ros communication without roscore

Christian Verbeek verbeek at servicerobotics.eu
Mon Feb 7 11:16:00 UTC 2011

Dear all,

It might be quite unusual but I would like to communicate with a ROS
system without connecting to a roscore. The problem I see is the
following. My robots run Ubuntu and are perfectly suited to run ROS. The
app for programming these robots is a Windows program. We already ported
ROS to Windows (http://ros-win32.servicerobotics.eu/). In general we
would be able to integrate ROS into our Windows app and connect to the
roscore running on the robots.

This will not do for the following reasons:

1) The IP address of the robot is not fixed, i.e. can be change by the
user. In order to be able to connect from the outside to the robot
ROS_MASTER_URI and ROS_IP on the robot would have to reflect the current
IP address. This might not be a general problem but makes things quite
complicated for the user when the IP address has to be changed. I would
prefer to set ROS_MASTER_URI and ROS_IP on the robot to as
this will always work.

2) We also have a simulator for our robot which is also a Windows
application. If we would use ROS to connect to our robot we would have
to run a roscore on Windows and connect the simulated robot to this ROS
master. With a single simulated robot this might work. But when we
simulate more than one robot we are getting in very big trouble because
there are many statics in libros. The robots are loaded at runtime to
the simulator and the statics make it impossible to handle the robots
individually as it is done right now.

What we would need is a point to point communication with a specific ROS
node. We know the IP address of the robot and we know which nodes are
running there. Is there a way to connect to a node's topic directly? Or
is there a better solution to my problem?


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