Hi all, I have a turtlebot, and add a hokuyo UST 10LX, but now with trouble in mapping . below is the sequence:

1. Add lidar module to robot's urdf file. $ sudo vi urdf/turtlebotlibrary.urdf.xacro <parent link="baselink" />

2. Edit launch to load lidar' driver $ sudo vi /opt/ros/indigo/share/turtlebotbringup/launch/minimal.launch <node name="hokuyo" pkg="urgnode" type="urgnode"> <param name="frameid" value="baselaserlink"/> < !– remap from="scan" to="base_scan" ==This is no longer needed / –> < /node>

3. Then try to map. $ roscore $ roslaunch turtlebotbringup minimal.launch $ roslaunch turtlebotnavigation gmapping_demo.launch

4. But meet error: Could not find a connection between 'map' and 'base_link' because they are not part of the same tree. Tf has two or more unconnected trees.

5. troubleshooting like this: 5.1 $ rosrun rqttftree rqttftree sure, /map is seperated, not belong to any part.

5.2 $ rosrun tf tfecho map baselink meet the same hints: Could not find a connection between 'map' and 'base_link' ...

5.3 $ rosrun tf tfecho baselink baselaserlink Exception thrown:"baselaserlink" passed to lookupTransform argument source_frame does not exist.

1. So I am confused. I already add a Lidar module to robot urdf module: baselaserlink is child and baselink is parent. so, since I change the urdf file, I think the ros system will mataintent the tf transform tree automaticly, but how I can not sucessfuly echo the baselink ---> baselaserlink , why this chain failed?

Thank you advanced!!!