[ros-users] Navigation stack : Error : Aborting because a valid plan could not be found

[Eitan Marder-Eppstein]

Shanker,

On Tue, Nov 30, 2010 at 6:07 PM, shankerk <shankerkeshavdas at gmail.com>wrote:

>
> Hi Eitan,
>
> Thanks for your reply. I tried the "RVIZ with navigation stack" tutorial.
> The map was displayed properly, and I also added the pose array. But I was
> unable to display the polygon showing the robot footprint. RVIZ warns me
> that there are no messages received in
> move_base/local_costmap/robot_footprint. There are also no messages
> received
> for move_base/local_costmap/obstacles or inflated obstacles. And indeed,
> when I 'rostopic echo' robot_footprint, I get no messages.
>

Are you sure that the publish_frequency parameter on the local costmap is
set to something other than 0?  You can find a description of the parameter
here:
http://www.ros.org/wiki/costmap_2d#Rate_parameters. If its not set, or set
to 0, the costmap won't actually publish any obstacle information. This
could be the reason that you're not seeing anything coming through on those
topics.


> At this point, I went through all my files again and noticed that in
> 'costmap_common_params.yaml', I had written the robot footprint values in
> centimeters and not in meters. I corrected this, so now the file looks
> like:
>

While this wasn't the problem you're having right now, it would have caused
issues later. Meters are the correct units for any distance related
parameters used by the navigation stack.


>
> Costmap_common_params.yaml
>
> obstacle_range: 2.5
> raytrace_range: 3.0
> footprint: [[0.275,0.325], [-0.275,0.325], [-0.275,-0.325], [0.275,-0.325]]
>
> observation_sources: laser_scan_sensor
> transform_tolerance: 2.0
> laser_scan_sensor: {sensor_frame: laser, data_type: LaserScan, topic:
> /scan,
> marking: true, clearing: true}
>
> inflation_radius: 0.55
>
> I ran the simulation again. And the errors are still the same with no
> differences. So I believe that was not the problem anyway.
>
> When I run the Rviz with navigation goals tutorial,
>
> I get the warning:
> [ INFO] [1291168915.975023299]: Received a 384 X 832 map at 0.100000 m/pix
>
> [ WARN] [1291168933.842753803]: The origin for the sensor at (0.10, -0.00,
> 0.00) is out of map bounds. So, the costmap cannot raytrace for it.
> [ WARN] [1291168986.842490604]: The origin for the sensor at (0.10, -0.00,
> 0.00) is out of map bounds. So, the costmap cannot raytrace for it.
>

These warnings imply that your robot is not on the map. You'll want to set
the initial pose of the robot using rviz to initialize AMCL and place the
robot in the correct place. Until the robot's location is contained within
the map I wouldn't expect much to work so I think that getting localization
up and running is probably the best thing to focus on at this point.

Hope this helps,

Eitan


>
> At this point, roswtf gives me:
>
> roswtf:
> shanker at DFKIShankerMBpro:~/Workspace/nifti/initial/subarchitectures/
> navigation.sa$
> roswtf
> Loaded plugin tf.tfwtf
> Package: navigation.sa
>
> ================================================================================
> Static checks summary:
>
> No errors or warnings
>
> ================================================================================
> Beginning tests of your ROS graph. These may take awhile...
> analyzing graph...
> ... done analyzing graph
> running graph rules...
> ... done running graph rules
> running tf checks, this will take a second...
> ... tf checks complete
>
> Online checks summary:
>
> Found 2 warning(s).
> Warnings are things that may be just fine, but are sometimes at fault
>
> WARNING The following node subscriptions are unconnected:
>  * /amcl:
>    * /reset_time
>  * /rviz_1291167645895723737:
>    * /reset_time
>  * /move_base:
>   * /move_base_simple/goal
>   * /move_base/cancel
>   * /reset_time
>   * /tf_message
>
> WARNING The following nodes are unexpectedly connected:
>  * /driver->/rosout (/rosout)
>  * /move_base->/rosout (/rosout)
>  * /initialpose->/rosout (/rosout)
>  * /sicklms->/rosout (/rosout)
>  * /amcl->/rosout (/rosout)
>  * /rviz_1291167645895723737->/rosout (/rosout)
>  * /map_server->/rosout (/rosout)
>  * /tflaserlink->/rosout (/rosout)
>  * /odomesub->/rosout (/rosout)
>
> I will check localization without navigation and post my results.
>
> Thanks for your help!
>
> Shanker
> --
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