turtlebot2 /odom and base_footprint tf

Question

Hello, I've been working with a turtlebot with a roomba base for which I developed some very simple algorithm like just going to a point. To know the current position of the robot I used the /odom message published by the turtlebot. To visualize the result I plotted the base_footprint on rviz. The robot was moving correctly and it reached the correct position in rviz.

Now we got some new turtlebot 2 with kobuki base on which I tried to apply the same algorithm. In this case the position given by the /odom message was different to the position given by the base_footprint tf. For instance /odom would say that the robot hat reached the position (0,0), actually with about half a meter of error, but the base_footprint tf was giving a different position, in rviz the robot was not at (0,0) but half meter away or so.

I would like to know it that behavior is normal or not. One difference between the two robots is that second one has a gyro and the other doesn't. Could it be that one of the measures is integrating it and the other is not?

Thanks

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Originally posted by focs on ROS Answers with karma: 46 on 2013-07-18

Post score: 0

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Original comments

Comment by focs on 2013-07-29:
Thanks! that confirms my thoughts.

Answer 1

Not sure about the 0.5 m difference, but odom and base_footprint can be different , as the first one is provided by motor encoders and the second by fussing (robot_pose_ekf) odom with gyro data. However, odom_combined and base_footprint should provide the same pose.

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Originally posted by jorge with karma: 2284 on 2013-07-21

This answer was ACCEPTED on the original site

Post score: 0