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robot_localization: yaw and position scaled down

asked 2015-04-17 09:22:03 -0500

quantumflux gravatar image

We have a setup on a Kobuki where we use the robot_localization package to fuse sensor data consisting of wheel odometry and landmark recognition, which is complemented by amcl to correct the odometry data while no landmarks are visible.

For now, the landmark system is not providing input, but the wheel odometry is fed to an ekf_localization_node which provides the odom -> base_footprint (analogous to base_link) transform. amcl receives the filtered odometry output produced by the ekf_localization_node and provides the map -> odom transform.

The ekf_localization_node however seems to "filter" the odometry in a weird way: The x and y position moves in the right direction, but only by half the distance of what it should do, whereas the yaw movement is scaled to maybe a 100th of it's original amount. What I would like to have happen is that the odometry input leads to a somewhat similar output on the /filtered/odometry topic.

Another issue which might be related is that the output on the /filtered/odometry topic seems to very slowly drift in both the xy-position as well as the yaw.

robot_localization launch file

<launch>
<node pkg="robot_localization" type="ekf_localization_node" name="ekf_localization" clear_params="true">

  <param name="frequency" value="60"/>  

  <param name="sensor_timeout" value="0.05"/>  

  <param name="two_d_mode" value="true"/>

  <param name="map_frame" value="map"/>
  <param name="odom_frame" value="odom"/>
  <param name="base_link_frame" value="base_footprint"/>
  <param name="world_frame" value="odom"/>

  <param name="odom0" value="/odom"/>


  <rosparam param="odom0_config">[true, true, false, 
                                  false, false, true, 
                                  false, false, false, 
                                  false, false, false,
                                  false, false, false]</rosparam>



  <param name="odom0_differential" value="true"/>


  <param name="print_diagnostics" value="false"/>

  <param name="debug"           value="false"/>
  <param name="debug_out_file"  value="/home/***/debug_ekf_localization.txt"/>

  <rosparam param="process_noise_covariance">
          [0.05, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
           0.0, 0.05, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
           0.0, 0.0, 0.06, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
           0.0, 0.0, 0.0, 0.03, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
           0.0, 0.0, 0.0, 0.0, 0.03, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
           0.0, 0.0, 0.0, 0.0, 0.0, 0.06, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
           0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.025, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
           0.0, 0.0, 0.0, 0.0, 0.0 ...
(more)
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answered 2015-04-17 12:11:38 -0500

Tom Moore gravatar image

This almost always points to a covariance issue, especially when you're using differential mode. Can you provide sample odometry message data? Also, which version of the software are you using?

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It's should be the most up-to-date version that's in the hydro repositories for precise pangolin, which - judging by the file name - is version 1.1.7

Unfortunately, I won't be able to provide a sample message until Monday as I don't have access to the lab during weekends.

quantumflux gravatar imagequantumflux ( 2015-04-17 14:39:33 -0500 )edit

Hadn't noticed that I never updated this again. It was in fact an issue with the covariance being set incorrectly. Because the covariance values were too high, the new measurements were accepted only as very inaccurate approximations and thus had little effect on the result.

quantumflux gravatar imagequantumflux ( 2015-06-30 04:07:36 -0500 )edit

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Asked: 2015-04-17 09:15:00 -0500

Seen: 238 times

Last updated: Apr 17 '15