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Navigating with a differential drive rectangular robot [closed]

asked 2013-05-24 10:56:23 -0500

marcusrm gravatar image

Currently we are using the Navfn global planner with the Trajectory_Rollout local planner on our differential-drive robot that is approximately 1 meter by 0.6 meters (with the center of the differential-drive being approximately 0.35 meters from the back of the robot). You can see a picture of our robot here:

image description

So far we have had limited success with our path planning. At the moment we believe that our biggest problem is that the robot will attempt to keep its center point (the center of the wheelbase) on the global path at all times, and if it moves slightly off the path it will end up spinning (usually a multiple of 360 degrees) until it merges back onto the path where it left off with the correct heading. (We have already tried all suggestions from this thread those linked on the same page)

We have been reading old forum messages and we think that our problem may be that the Navfn planner does not give pose requirements to local goals, meaning that when we reach curves on our path the robot will come in with the wrong heading and start its spinning problem. We wanted to use the pose_follower based on dialogue from this archive but it gave no messages and didn’t move when we ran it. We also tried the sbpl_lattice_planner to no avail.

We are wondering whether or not a global/local planner has been developed that works well with rectangular shaped robots. From our experience and what we’ve read from other users with similarly shaped differential drive robots, tuning the parameters on our current planners is not enough to get a reliable solution. We looked at the development on the PR2 for cart pushing, but we were unsure if we should attempt to make our robot "look" like a smaller square robot pushing a similarly shaped square cart.

Your feedback is greatly appreciated.

Here are our parameters that we're currently using:

parameters directory

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Closed for the following reason the question is answered, right answer was accepted by marcusrm
close date 2013-05-29 09:41:08

1 Answer

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answered 2013-05-29 09:27:12 -0500

David Lu gravatar image

I'm not an expert on tuning these parameters, but have you tried lowering path_distance_bias (Documentation)

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Our problem has since been resolved (mostly...). We think that our robot was too long and rectangular to use the trajectory_planner, however we were able to fix some bugs that were preventing us from using the DWA planner which works much better.

marcusrm gravatar image marcusrm  ( 2013-05-29 09:38:13 -0500 )edit

We think that the "forward_point" parameter is probably the best improvement for us because it keeps our robot's heading more consistent.

marcusrm gravatar image marcusrm  ( 2013-05-29 09:39:48 -0500 )edit

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Asked: 2013-05-24 10:56:23 -0500

Seen: 1,511 times

Last updated: May 29 '13