[ros-users] Navigation Stack on tight places

Thu Nov 18 19:31:58 UTC 2010

Sorry Eitan!

I should have sent everything compressed the first time! I compressed the
pkg. To run it just put it on your ROS_PACKAGE_PATH, roscore, roscd
roomba_stage and then open stage, launch move_base and open rviz (also
sending a roomba_stage.vcg file):

rosrun stage stageros roomba_lse_arena.world
roslaunch roomba_stage move_base_lse_arena.launch

Just send the robot to the top right corner and it will likely stall on the
wall.

Anyways I just downloaded navigation_experimental! So dwa_local_planner
seems to be a lib, how should I use it to get the robot up and running with
it? Just give me some quick pointers.

Cheers,

Gonçalo Cabrita
ISR - University of Coimbra
Portugal

On Thu, Nov 18, 2010 at 7:02 PM, Eitan Marder-Eppstein <
eitan at willowgarage.com> wrote:

> Gonçalo,
>
> It looks like you missed a file called "arena_obstalces.pgm" in what you
> sent which is needed by the roomba_ise_arena.world file. Is there any way
> you can just tar up the package you use to bring things up? Ideally this
> would include all the configuration files and launch files you're using to
> bring up stage and the navigation stack and would save a bit of grief in me
> recreating the same package on my end.
>
> Thanks a bunch,
>
> Eitan
>
> 2010/11/18 Gonçalo Cabrita <goncabrita at gmail.com>
>
>> Hi Eitan!
>>
>> Thanks for your reply.
>>
>> I'm attaching the files needed to run the sim on Stage. It is the same
>> setup we have on the real arena right now, and the results on the real robot
>> are pretty similar to the simulation.
>>
>> I'll most definitely take a look at the experimental nav stack. I'd like
>> to try the dwa_local_planner on the roomba to see what happens! I'll be
>> posting some feedback and most likely a bunch of questions!
>>
>> Gonçalo Cabrita
>> ISR - University of Coimbra
>> Portugal
>>
>>
>> On Thu, Nov 18, 2010 at 5:54 PM, Eitan Marder-Eppstein <
>> eitan at willowgarage.com> wrote:
>>
>>> Hey guys,
>>>
>>> So, to join in the discussion. From the video, it looks like the
>>> base_local_planner gets stuck in a local minimum with the parameters
>>> configured as they are. Is there any way that you can post the package used
>>> to create that video so that I can play around a little bit? I've wanted to
>>> have a case in simulation where a diff drive robot behaves badly and it
>>> seems like this is a simple one that could help me track down some issues
>>> the navigation stack has with diff drive robots. With that said, its true
>>> that no one local planner is going to fit all robots.
>>>
>>> We've started development of some other local planners in the
>>> navigation_experimental stack that might also be worth checking out. One is
>>> called dwa_local_planner and is a much cleaner version of the
>>> base_local_planner that includes things like scaling the robot's footprint
>>> based on speed, allowing for holonomic robots to explore more of the y
>>> velocity space, and exposing parameters via dynamic reconfigure to make
>>> tuning them a lot easier... we're testing it on the PR2 right now, not sure
>>> how it'll work on a diff-drive robot. There's also the pose_follower which
>>> attempts to follow a plan exactly, stopping in the presence of obstacles.
>>> This also hasn't been tested on diff-drive robots and I'd expect it could
>>> use a few tweaks to really work well, but it might be something to look at.
>>> One thing to keep in mind with all this, however, is that the packages in
>>> navigation_experimental are, well, experimental, so you're likely to run
>>> into some issues from time to time, there are no guarantees about API
>>> stability yet, and documentation isn't great.
>>>
>>> Hope all is well and please do post the simulation package as I'd love to
>>> take a look at things,
>>>
>>> Eitan
>>>
>>> 2010/11/18 Gonçalo Cabrita <goncabrita at gmail.com>
>>>
>>> We've been a bit busy porting everything that moves around here to ROS!
>>>> We'll update our repository in the next week with everything we've got!
>>>>
>>>> I'm attaching the param files we use for the roombas.
>>>>
>>>> I'm surprised the creates don't have decent odometry since they were
>>>> design for research. We have considered using cheap webcams with visual
>>>> odometry to replace the roomba's odometry, but I haven't had time to look
>>>> into it. If my memory serves me when we opened a roomba we found a hall
>>>> sensor with 4 magnets tied to the motor shaft. So I'm guessing direction is
>>>> determined by the motor speed. And that why when you push the roomba the
>>>> odometry doesn't count back!
>>>>
>>>> I'm really interested in solving this matter. If the problem really is
>>>> from the nav stack we're in big trouble since everything here is diff drive!
>>>> We have roombas, erratics and scouts!
>>>>
>>>> Gonçalo Cabrita
>>>> ISR - University of Coimbra
>>>> Portugal
>>>>
>>>>
>>>> On Thu, Nov 18, 2010 at 3:45 PM, Steven Martin <
>>>> s34.martin at connect.qut.edu.au> wrote:
>>>>
>>>>>  Yeh I think my problem is related to odometry, the iCreates don't
>>>>> have any encoders. I thought they did but after looking closer at the driver
>>>>> I am pretty sure its just openloop. Do you have the parameters for amcl in
>>>>> your repository? I had a look but couldn't see them anywhere.
>>>>>
>>>>> I have the code for the pursuit path follower checked in @
>>>>> launchpad.net/cmr but its very incomplete. It will compile, you can
>>>>> launch it and it will try and follow a path but it doesn't have any obstacle
>>>>> avoidance and I think I have one of my signs wrong in the code as it  didn't
>>>>> appear to do much following  from the very limited testing I have done.
>>>>>
>>>>> Have a look, its basically as stripped down as I could make a local
>>>>> path planner while still fitting in the ROS framework. Also due to the
>>>>> pretty well useless iCreate odometry I chose to implement this in the global
>>>>> frame and this may have some adverse affects if you are only running
>>>>> localiser @ 3Hz.
>>>>>
>>>>> I will probably have time to look at this next week but I think this is
>>>>> a problem for anybody using nonholonomic robots with the Nav Stack so I
>>>>> would be surprised if someone else hasn't already got a better solution.
>>>>>
>>>>> Steve
>>>>>
>>>>>  ------------------------------
>>>>> *From:* ros-users-bounces at code.ros.org [ros-users-bounces at code.ros.org]
>>>>> on behalf of Gonçalo Cabrita [goncabrita at gmail.com]
>>>>> *Sent:* Friday, 19 November 2010 12:52 AM
>>>>> *To:* User discussions
>>>>> *Subject:* Re: [ros-users] Navigation Stack on tight places
>>>>>
>>>>>  Hi Steven!
>>>>>
>>>>>  "ts not a failure case but do you also see the one where it turns a
>>>>> little bit away from the path then does loop around to rejoin it.?"
>>>>>
>>>>>  You we also get that a lot! The robot never sticks to the path the
>>>>> planner outputs, it wonders around a lot.
>>>>>
>>>>>  We are using Roombas 560 with Eee PCs and Hokuyo lasers. We launch
>>>>> the Roomba the laser and the tf broadcaster on one file and map server, amcl
>>>>> and move base on another one. We have the map updaters running at 3Hz and
>>>>> the path planner at 5Hz. Still sometimes the EeePC skips a loop!
>>>>> Furthermore, I dunno how the Create is but our Roombas have nasty odometry!
>>>>> The encoders have only 1 channel with 4 pulses per motor turn!
>>>>>
>>>>>  Anyways, I'm not familiar with the nav stack code, but I would like
>>>>> to help if possible!
>>>>>
>>>>>  Gonçalo Cabrita
>>>>> ISR - University of Coimbra
>>>>> Portugal
>>>>>
>>>>> On Thu, Nov 18, 2010 at 2:35 PM, Steven Martin <
>>>>> s34.martin at connect.qut.edu.au> wrote:
>>>>>
>>>>>>  Yep see that one all the time. I think the implementation of DWA is
>>>>>> flawed for tank steer robots.
>>>>>>
>>>>>> Its not a failure case but do you also see the one where it turns a
>>>>>> little bit away from the path then does loop around to rejoin it.?
>>>>>>
>>>>>> I started implementing just pure pursuit path follower to replace DWA
>>>>>> but haven't quite got it working and been too busy with other stuff. I think
>>>>>> we need to implement some other local planners or just path followers.
>>>>>>
>>>>>> Also what are you using for the localization? I haven't been able to
>>>>>> get AMCL to work reliably on the iCreates.
>>>>>>  ------------------------------
>>>>>> *From:* ros-users-bounces at code.ros.org [
>>>>>> ros-users-bounces at code.ros.org] on behalf of Gonçalo Cabrita [
>>>>>> goncabrita at gmail.com]
>>>>>> *Sent:* Thursday, 18 November 2010 11:51 PM
>>>>>> *To:* ros-users at code.ros.org
>>>>>> *Subject:* [ros-users] Navigation Stack on tight places
>>>>>>
>>>>>>    Hi everyone!
>>>>>>
>>>>>>  We've been using the nav stack on our Roombas for quite a while now,
>>>>>> mostly on the corridors of ISR without any problems.
>>>>>>
>>>>>>  However we have a small 4mx3m arena we built specifically for
>>>>>> testing odor search algorithms in which we recently started to run some
>>>>>> experiments. We quickly found out that the nav stack has some problems
>>>>>> moving the robot around in tight places. Quite often we get
>>>>>> the behavior that can be seen in the following video...
>>>>>>
>>>>>>  http://www.youtube.com/watch?v=vy9xoNvmktg
>>>>>>
>>>>>>  In the video we are running a Roomba inside our arena in Stage with
>>>>>> perfect odometry. The robot stalls against a wall and stays there for
>>>>>> 30mins until we stop it. On occasion the robot eventually gets out after a
>>>>>> while.
>>>>>>
>>>>>>  At first I thought this could be happening because of the poor
>>>>>> performance of the EeePCs the Roombas carry around or because of the
>>>>>> Roomba's crappy odometry, but in Stage on a Core2Duo laptop we were able to
>>>>>> see the same behavior.
>>>>>>
>>>>>>  Has anyone experienced this behavior before?
>>>>>>
>>>>>> _______________________________________________
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>>>>>>
>>>>>
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