[ros-users] Avoiding Collisions between robots

[davidbsp at iol.pt]

Hello everyone,

I have been making some experiments on ROS together with Stage, using  
multiple mobile robots in the same environment.
All robots run the navigation stack. However, sometimes they collide  
with each other.

As far as I understood, the navigation stack assumes a static  
environment. I have tried to stop one robot when two robots are  
crossing each other (by sharing their positions in a common topic) and  
still the moving robot often drives into the stopped robot. I also get  
collisions by stopping both of them and resetting their goals.

Should I redefine the parameters of the local planner or this is not  
the way to go? I have tried both DWA and Trajectory Roll Out with  
different parameters and had no luck.

I also have tried to set intermediate goals when robots are close, in  
order to keep them away from each other. However using the navigation  
stack in tight places with two robots, a "repelling force" effect on  
the robots seems to prevent them to achieve their intermediate goals.

I had better luck by giving the robots velocity commands in opposite  
directions when they are close to each other, however this is a  
solution that i was not willing to use, since it bypasses the  
navigation stack and it highly depends on the free space around the  
robots.

I was wondering if there is any mechanism to prevent robots from  
colliding with each other. If not, can you give me hints on how to  
create such a mechanism?

Thank you in advance,


David Portugal

Mobile Robotics Laboratory
Institute of Systems and Robotics
University of Coimbra

________________________________________________________________________________
Junte todos os seus créditos no Único da Capital Mais...
...reduza as suas despesas mensais.
Saiba mais em http://www.iol.pt/correio/rodape.php?dst=0901051