hector_slam with odometry?

asked 2013-06-03 05:28:24 -0500

496 ●66 ●79 ●88

updated 2013-06-05 02:49:19 -0500

Hi,

My data is from a big tunnel, about 700m long, and I want to do some mapping.
The problem is, that each scan looks nearly the same, with no big changes and the scanmatcher without odometry has some problems...
The robot thinks he is always standing at the same position instead of driving forwards.

Soon as I am in the tunnel, scanmatcher seems to overrule the odometry data and the robot is not moving any farther.
Is it possible to change that or somehow deactivate scanmatching?

  <launch>

 <node pkg="tf" type="static_transform_publisher" name="scanmatcher_odom_broadcaster" args="0 0 0 0 0 0 odom map
100"/> 
 <node pkg="tf" type="static_transform_publisher" name="scanmatcher_baselink_broadcaster" args="0 0 0 0 0 0 scanmatcher_frame base_link 100"/>

 <include file="$(find velodyne_mapping)/launch/assembler_to_2d_laser.launch"/>  

 <node pkg="hector_mapping" type="hector_mapping" name="hector_mapping" output="screen">


<param name="pub_map_odom_transform" value="false"/>
<param name="base_frame" value="base_link" />
<param name="odom_frame" value="odom"/>
<param name="output_timing" value="false"/>

<param name="scan_topic" value="scan"/>

# Map size / start point 
<param name="map_resolution" value="0.1"/>
<param name="map_size" value="4096"/>
<param name="map_start_x" value="0.5"/>
<param name="map_start_y" value="0.5" />

# Map update parameters 
<param name="update_factor_free" value="0.4"/>
<param name="update_factor_occupied" value="0.9" />    
<param name="map_update_distance_thresh" value="0.4"/>
<param name="map_update_angle_thresh" value="0.06" />


 </node>

 </launch>

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answered 2013-06-05 03:11:36 -0500

Stefan Kohlbrecher

24361 ●173 ●299 ●444 https://www.energy-rob...

updated 2013-06-05 03:14:46 -0500

Ok, I should probably update the documentation to state this more clearly: The odom frame is used in hector_mapping mainly to provide the same interface as gmapping does. Internally, odometry is completely ignored for mapping currently and just used to be able to publish the map->odom transform correctly. This is advantageous if you can't rely on odometry, but obviously a disadvantage in this tunnel scenario. Support for odometry could be added, but that will require some effort (if someone wants to look at it :) ).

That being said, I'm pretty sure I know which robot was used for this dataset and with the ton of sensors you strapped onto it there are a lot of other approaches you could try. The Velodyne data plus some registration approach (for example ethzasl_icp_mapping) would be my first try.

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Thank you! That clears all up. Will have a look at it.

madmax ( 2013-06-05 04:22:34 -0500 )edit

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answered 2013-06-03 05:42:07 -0500

allenh1

3045 ●62 ●89 ●110 http://allen-software.com/

Yes, you certainly can use odometry.

In your launch file, you will need to set up the following parameters to the correct tf frames for your platform. If you don't have a launch file, I'd make one. Also, take a look at the pr2 launch file that comes with hector_slam. It uses the robot's odometry.

<param name="pub_map_odom_transform" value="true"/>
<param name="map_frame" value="map" />
<param name="base_frame" value="base_frame" />
<param name="odom_frame" value="odom" />

PS: that's a HUGE tunnel.

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I tried that, but I somehow have a scanmatcher frame parallel to my base_link. Should I just rename this frame to base_link? Yeah, the tunnel is about 1.6km or so, but we went "only" till the middle...

madmax ( 2013-06-03 06:20:47 -0500 )edit

Yes, that should work.