Ming,

In addition to setting the "robot_base_frame" and "global_frame" on the
global._costmap,  you'll also need to set it on the local_costmap which is
used for obstacle avoidance and often operates in a different frame from the
local map. The local_costmap is probably the one giving the error message
you're describing.

Please see the following page for an explanation of configuring the two
costmaps used by the navigation stack:
http://www.ros.org/wiki/navigation/Tutorials/RobotSetup#Costmap_Configuration_.28local_costmap.29_.26_.28global_costmap.29
.

Hope all is well,

Eitan

On Fri, May 14, 2010 at 2:36 AM, 刘明 <liu.ming.prc@gmail.com> wrote:

> Hi everyone,
>
> Thanks for you kind and prompt replies.
>
> But the move_base is still asking for a frame with frame_id /base_link
> (output in rxconsole):
>
>> Waiting on transform from base_link to /map to become available before
>> running costmap, tf error: Frame id /base_link does not exist!
>>
> when I launch the launch-file as below, where of course I have corrected
> the naive spelling mistake @-| , as:
>
> <launch>
>>
>>         <param name="global_costmap/robot_base_frame"
>> value="/robot_base"/>
>>         <param name="global_costmap/global_frame" value="/world"/>
>>     <node name="move_base" pkg="move_base" type="move_base"
>> respawn="true">
>>     </node>
>>
>> </launch>
>>
>
> We had a transformation .yaml before, which I forgot to mention.
> The result of
>
>> $ rosrun tf view_frames
>> $ evince frames.pdf
>>
>> showed that the frames are correctly linked.
>
> The result of
>
>> $rosrun tf tf_echo /robot_base /world
>
>  returns correct transformation when I move the robot around.
>
> I also output the parameters got by "move_base" node, by adding:
>
>>  ROS_INFO("FrameIDs: %s %s", robot_base_frame_.c_str(),
>> global_frame_.c_str());
>>
> to move_base.cpp:66. The output from the rxconsole is FrameIDs:
> /robot_base /world which is correct.
>
> It sounds like the parameters are not correctly passed to the costmap or
> else nodes. Any other hints?
>
> Best regards,
> Ming
>
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