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Helping diff. drive robot get through doorways

asked 2023-04-12 09:36:46 -0600

coatwolf gravatar image

updated 2023-04-12 09:37:19 -0600

Hey folks!

I'm working on a differential drive SLAM robot and I have things working pretty well. I'm able to:

  • Create a map of my apartment using slam_toolbox
  • Navigate from room to room using Nav2 and Goal Poses on RViz2

First off a big thanks to Steve Macenski and all the folks who maintain these open source packages. I've really been enjoying using them so far.

I'm having a problem where my robot is getting "stuck" in doorways that are plenty big for it to navigate through. It doesn't happen every time, and I'd say 50% of the time the robot just breezes through and passes to the next room with no problem. The other 50% though the robot will stop at the threshhold, start rotating to and fro in a confused manner, and sometimes it works itself out after 30sec or so, but most of the time it ends up getting totally stuck until I give it a little help with the joystick.

I have noticed that this happens more often when moving to a room that is positioned a U-turn away from the current room. For instance, the robot can usually handle these paths with no problem:

image description

image description

Whereas it almost ALWAYS gets stuck moving between these two rooms:

image description

It doesn't like something about that turn radius, even though practically there is plenty of room to pass (sometimes it manages to).

What I have tried:

  • Confirming the URDF descriptions are accurate to the robot's physical dimensions
  • Playing with the wheel separation multiplier in the controller configuration file

But can't seem to shake this issue. Perhaps there is some setting in Nav2 related to the costmap that I can finetune to get this working? Thanks in advance for any suggestions!

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Have you installed the plugin in rviz to display the Local Costmap? If you have "fake" obstacles in the Local Costmap, the Local Planner may be unable to find an open path.

Mike Scheutzow gravatar image Mike Scheutzow  ( 2023-04-13 11:15:58 -0600 )edit

Yes you can see in the images in my post that I have the costmap displayed in rviz2. Unless you meant something else. I have made some progress (see my response in a comment below).

coatwolf gravatar image coatwolf  ( 2023-04-16 01:31:44 -0600 )edit

The Global Costmap is different from the Local Costmap. It would benefit you to understand the difference.

Mike Scheutzow gravatar image Mike Scheutzow  ( 2023-04-16 07:40:22 -0600 )edit

Apologies, I missed the "Local" keyword. Yes I have viewed the local costmap as well and there doesn't seem to be an issue of phantom obstacles. Thanks for the reply.

coatwolf gravatar image coatwolf  ( 2023-04-16 07:47:49 -0600 )edit

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answered 2023-04-16 01:37:45 -0600

coatwolf gravatar image

I haven't solved this entirely BUT I am closer now that I have discovered the costmap parameters file which I was unaware of prior to my post. You can find info here and the code here.

I had originally installed the nav2 stack using apt which made it inconvenient to access this file, so I apt removed all of the packages and then reinstalled by cloning from the nav2 repository (guide here) to a dedicated nav2_ws and editing / building from there.

By playing with the following values I am slowly but surely improving my robot's mobility through turns and doorways:

  • footprint_padding
  • inflation_radius
  • cost_scaling_factor
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This is right, I had to adjust inflation_radius and it worked.

hunterlineage1 gravatar image hunterlineage1  ( 2023-04-16 01:41:54 -0600 )edit

Thanks for the reply! Was it simply a matter of reducing the radius?

coatwolf gravatar image coatwolf  ( 2023-04-16 01:50:56 -0600 )edit

Yes, but you might still have to tune the footprint_padding and cost_scaling_factor.

hunterlineage1 gravatar image hunterlineage1  ( 2023-04-16 12:54:25 -0600 )edit

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Asked: 2023-04-12 09:36:46 -0600

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Last updated: Apr 16 '23