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Hello I am new to ROS and using Robot_localisation package. As given in the tutorial I ran two instances of ekf_localisation. My navsat transform node gives zero output and I keep getting a warning : Could not obtain transform from gps_link to base_link. Error was "gps_link" passed to lookupTransform argument source_frame does not exist.

My launch file is :-

<!-- Test launch file for two EKF instances and one navsat_transform instance -->

<launch>

  <node pkg="tf2_ros" type="static_transform_publisher" name="bl_imu" args="0 0 0 0 0 0 1 base_link imu_link" />

  <!-- Local (odom) instance -->
  <node pkg="robot_localization" type="ekf_localization_node" name="ekf_localization_local" clear_params="true">
    <param name="frequency" value="30"/>
    <param name="sensor_timeout" value="0.1"/>
    <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_link"/>
    <param name="world_frame" value="odom"/>

    <param name="transform_time_offset" value="0.0"/>

    <param name="odom0" value="/RosAria/pose"/>
    <param name="imu0" value="/imu_data"/>

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

    <rosparam param="imu0_config">[false, false, false,
                                   true,  true,  true,
                                   false, false, false,
                                   true,  true,  true,
                                   true,  true,  true]</rosparam>

    <param name="odom0_differential" value="false"/>
    <param name="imu0_differential" value="false"/>

    <param name="odom0_relative" value="false"/>
    <param name="imu0_relative" value="false"/>

    <param name="imu0_remove_gravitational_acceleration" value="true"/>
    <param name="print_diagnostics" value="true"/>

    <param name="odom0_queue_size" value="10"/>
    <param name="imu0_queue_size" value="10"/>

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

    <remap from="/odometry/filtered" to="/odometry/filtered/local"/>
  </node>

  <!-- Global (map) instance -->
  <node pkg="robot_localization" type="ekf_localization_node" name="ekf_localization_global" clear_params="true">
    <param name="frequency" value="30"/>
    <param name="sensor_timeout" value="0.1"/>
    <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_link"/>
    <param name="world_frame" value="map"/>

    <param name="transform_time_offset" value="0.0"/>

    <param name="odom0" value="/RosAria/pose"/>
    <param name="odom1" value="/odometry/gps"/>
    <param name="imu0" value="/imu_data"/>

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

    <rosparam param="odom1_config">[true, true, false,
                                    false, false, false,
                                    false, false, false,
                                    false, false, false,
                                    false, false, false]</rosparam>

    <rosparam param="imu0_config">[false, false, false,
                                   true,  true,  true,
                                   false, false, false,
                                   true,  true,  true,
                                   true,  true,  true]</rosparam>

    <param name="odom0_differential" value="false"/>
    <param name="odom1_differential" value="false"/>
    <param name="imu0_differential" value="false"/>

    <param name="odom0_relative" value="false"/>
    <param name="odom1_relative" value="false"/>
    <param name="imu0_relative" value="false"/>

    <param name="imu0_remove_gravitational_acceleration" value="true"/>
    <param name="print_diagnostics" value="true"/>

    <param name="odom0_queue_size" value="10"/>
    <param name="odom1_queue_size" value="10"/>
    <param name="imu0_queue_size" value="10"/>

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

    <remap from="/odometry/filtered" to="/odometry/filtered/global"/>
 </node>

 <!-- navsat_transform -->
 <node pkg="robot_localization" type="navsat_transform_node" name="navsat_transform" respawn="true" output="screen">
    <param name="frequency" value="30"/>
    <param name="delay" value="3"/>
    <param name="magnetic_declination_radians" value="0.05"/>
    <param name="yaw_offset" value="0"/>
    <param name="zero_altitude" value="true"/>
    <param name="broadcast_utm_transform" value="true"/>
    <param name="publish_filtered_gps" value="true"/>
    <param name="use_odometry_yaw" value="false"/>
    <param name="wait_for_datum" value="false"/>

    <remap from="/odometry/filtered" to="/odometry/filtered/global"/>
    <remap from="/gps/fix" to="/gps_data"/>
    <remap from="/imu/data" to="/imu_data"/>
  </node>

</launch>

I have also attached a bag file of my sensor data https://drive.google.com/open?id=0B3oOeVRB6N26S3E4VEx2dk5WUGs

Originally posted by Anirvan0102 on ROS Answers with karma: 28 on 2016-06-14

Post score: 1

Original comments

Comment by Tom Moore on 2016-06-14:
Thanks for this. There's an issue on the GH page for r_l regarding this very thing, so I'll look into it today or tomorrow.

Comment by Anirvan0102 on 2016-06-14:
Hello Tom, thanks for replying so quick. I included a static transform of base_link ->gps_link in the launch file and the warning message stopped also navsat_transform node gave the output in robot's local frame .

Comment by Anirvan0102 on 2016-06-14:
this was the line I added in the launch file but I am getting terrible output from the odometry/filtered/global

Comment by asimay_y on 2016-06-14:
hi, @Anirvan0102, can you check your /odometry/gps topic ? is it NAN when you set use_odometry_yaw= false in navsat_transform_node? I met the same problem with you. but I just got one warning info of it, because I set the static tf transform.

Comment by Anirvan0102 on 2016-06-14:
Hey asimay_y, it is not NAN but the pose was exact zero and it was not changing as I was changing my robot's position. Later I set the static tf and I was getting the ouput of odometry/gps but my odometry/filtered/global was giving poor estimate.

Comment by asimay_y on 2016-06-14:
can you share your rosbag files and node graph? I also get poor estimate, and digging the cause..

Comment by Tom Moore on 2016-06-15:
Where is the attached bag file?

Comment by Anirvan0102 on 2016-06-15:
Sure asimay_y ... here is my bag file https://drive.google.com/open?id=0B3oOeVRB6N26S3E4VEx2dk5WUGs. My launch file is https://drive.google.com/open?id=0B3oOeVRB6N26MVdGdllzVE1yMEk. I will be thankful to you if you could find out some solution, I have been stuck here for quite a time

Comment by Anirvan0102 on 2016-06-15:
Hello Tom, I have added it Another update- I think there might be some problem with my imu_data because I ignored the imu and used odometry yaw and my odometry/filtered/global output improved. Here's my current launch file https://drive.google.com/open?id=0B3oOeVRB6N26a1ZxdFhpeUE0Z2M

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First, grab the latest source from the upstream repository.

Second, fix the following issues:

  1. Not sure how you recorded your bag file, but it looks to me like something other than ekf_localization_node is publishing the odom->base_link transform for your robot. You can't have two nodes publishing the same transform. Looking at the ROSARIA code, it appears to always publish the odom->base_link transform, and it appears you can't configure it. You'll have to either modify the ROSARIA code, use a different Pioneer ROS driver, or get rid of your odom instance of ekf_localization_node.
  2. (Minor, doesn't really affect anything) You have two_d_mode set to true, but you are fusing lots of 3D variables, including Z velocity from your odometry source and roll, pitch, their velocities, and Z acceleration from the IMU. Those will be ignored unless you turn of two_d_mode.
  3. In your odom EKF instance, you are fusing odometry variables that make sense, namely, the velocities. However, in your map instance, you are fusing absolute X and Y from both your GPS and your whee odometry. Those will probably not agree with each other, and the filter is going to jump back and forth rapidly.
  4. You are fusing the output of the odom EKF as an input to the map EKF. For a number of reasons, this isn't a good idea. Use the same raw input data for both.
  5. For some reason, your RosAria/pose topic has horrific covariances for yaw and yaw velocity, on the order of 1000.0. I'm going to venture a guess that the error on your rotational velocity is not 1000.0. This issue is very important, because it's going to cause strange behavior in the filter output. For example, when the robot turns, you may see lateral motion instead. This must be fixed.
  6. Your IMU data is really suspect. First, it's very low frequency, but beyond that, it also is all over the place. Do a rostopic echo /imu/data and watch it for a little.

You need to go back and do one thing at a time: make sure all your raw sensor data conforms to standards and is correct. Then fuse one sensor - e.g., odometry - into an EKF and make sure the output makes sense. Then fuse another sensor and verify again.

Originally posted by Tom Moore with karma: 13689 on 2016-06-15

This answer was ACCEPTED on the original site

Post score: 1

Original comments

Comment by Anirvan0102 on 2016-06-15:
Thank you Tom. I will try to make the necessary changes in the code.

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