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Pr2 whirling like a dervish

asked 2011-10-11 04:01:49 -0500

updated 2014-11-22 17:05:32 -0500

ngrennan gravatar image

When using the pr2_2dnav_local and setting a goal very close to an obstacle, the robot starts rotating in place. My guess is that this is related to the dynamic window controller, which can't find a suitable set of commands, even if the planner says the goal target is in a free cell. I've read the guide here, but I didn't find anything to solve this problem.

What parameters of the dwc should I change to avoid this effect?

A broader question is, would you use the default navigation stack to get close to an object (say a table) or do I need a custom package for that?

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I don't have a solution, but this is a failure mode I've experienced myself, as have several others. At least you aren't alone!
Mac gravatar image Mac  ( 2011-10-11 05:59:49 -0500 )edit
Several whirling robotic dervishes then!
Lorenzo Riano gravatar image Lorenzo Riano  ( 2011-10-11 06:12:36 -0500 )edit
Thumbs up for the question title! :-)
Martin Günther gravatar image Martin Günther  ( 2011-10-11 21:34:50 -0500 )edit
thanks :-D
Lorenzo Riano gravatar image Lorenzo Riano  ( 2011-10-12 03:33:38 -0500 )edit

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answered 2011-10-11 07:01:00 -0500

watts gravatar image

Lorenzo, you should try the "base_local_planner", which was default until cturtle. It does not have this spinning problem at all. The DWA local planner can be fun to watch, but you might be bored of this spinning behavior.

The default configuration file in pr2_navigation_config/move_base/base_local_planner_params.yaml will work well, but if you add the parameter "min_vel_x" to "0.10", the planner will be slightly more robust.

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base_local_planner solves the problem. in that the robot reaches the point. but then it get's stuck and it doesn't move anymore, even if it has reached a goal position. I guess there is still some fine tuning to do, but things are getting better.
Lorenzo Riano gravatar image Lorenzo Riano  ( 2011-10-12 03:07:24 -0500 )edit
Hi Lorenzo, did you solve the problem? We got the same here in Freiburg. If the robot gets too close to obstacles on the way or at the goal it does not finish rotating and does not continue the path. I have played around with the move_base parameters but was not able to fix it.
JuergenHess gravatar image JuergenHess  ( 2012-01-22 20:26:39 -0500 )edit

answered 2012-01-22 21:01:24 -0500

I have uploaded a set of parameters that "work" in the University of Ulster repository. The package is here.

The launch folder has a pr2_2dnav.launch that uses the correct parameters, listed in the params folder.

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Thanks. I will try that.
JuergenHess gravatar image JuergenHess  ( 2012-01-22 23:26:19 -0500 )edit

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Asked: 2011-10-11 04:01:49 -0500

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Last updated: Jan 22 '12