drive F5 platform some time ago. You remember? I had similar problems
> 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@gmail.com
> <mailto:goncabrita@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@connect.qut.edu.au
> <mailto:s34.martin@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 <http://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@code.ros.org
> <mailto:ros-users-bounces@code.ros.org>
> [ros-users-bounces@code.ros.org
> <mailto:ros-users-bounces@code.ros.org>] on behalf of Gonçalo
> Cabrita [goncabrita@gmail.com <mailto:goncabrita@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@connect.qut.edu.au
> <mailto:s34.martin@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@code.ros.org
> <mailto:ros-users-bounces@code.ros.org>
> [ros-users-bounces@code.ros.org
> <mailto:ros-users-bounces@code.ros.org>] on behalf of
> Gonçalo Cabrita [goncabrita@gmail.com
> <mailto:goncabrita@gmail.com>]
> *Sent:* Thursday, 18 November 2010 11:51 PM
> *To:* ros-users@code.ros.org <mailto:ros-users@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?
>
> _______________________________________________
> ros-users mailing list
> ros-users@code.ros.org <mailto:ros-users@code.ros.org>
> https://code.ros.org/mailman/listinfo/ros-users
>
>
>
> _______________________________________________
> ros-users mailing list
> ros-users@code.ros.org <mailto:ros-users@code.ros.org>
> https://code.ros.org/mailman/listinfo/ros-users
>
>
>
> _______________________________________________
> ros-users mailing list
> ros-users@code.ros.org <mailto:ros-users@code.ros.org>
> https://code.ros.org/mailman/listinfo/ros-users
>
>
>
> _______________________________________________
> ros-users mailing list
> ros-users@code.ros.org
> https://code.ros.org/mailman/listinfo/ros-users
Dr. Christian Verbeek
Robert-Koch-Str. 2, 82152 Planegg
Geschäftsführer: Dr. Christian Verbeek
(text/plain)