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I'm using the robot_localization package. The first ekf node to fuse odometry and IMU data. The second ekf node to fuse odometry, navsat_node output and IMU data. I use datum parameter in navsat's roslaunch to create a fixed transform between map and odom.

The first problem is that this transformation doesn't remain fixed.

The second question is: if i lose the GPS signal, the second kalman filter continues an open loop position estimation in map frame or gives the same output of the first ekf?


Originally posted by Niko on ROS Answers with karma: 33 on 2016-03-07

Post score: 0

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The datum parameter creates a fixed transform between the UTM grid and your world frame, not between map and odom. If your robot moves in the map or odom frame, then the transform between them will not be fixed. A fixed transform between map and odom means that your pose estimate in both frames is identical, which would almost never be the case.

If you lose GPS signal, then yes, you will continue to get a state estimate in your map instance of the EKF using just the odometry and IMU data. Redundancy is one of the key benefits of fusing multiple sources.


Originally posted by Tom Moore with karma: 13689 on 2016-03-07

This answer was ACCEPTED on the original site

Post score: 1


Original comments

Comment by Niko on 2016-03-08:
thank you so much. I thought that datum gave a fixed transform between map and odom but now the problem will be solved. :)

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