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Gmapping does not publish the pose of the robot as a pose per se (within a topic), but as a transform from 'map' to 'odom'.
In order to get the pose of the robot in the map that is built you have to get the current odometry of the robot (read your odometry topic) and then ask for the transform of that odometry (that is in 'odom' frame) to the 'map' frame. The result will be a pose in 'map' frame (the coordiantes of the robot in the map)
Then, in order to visualize the robot path through the map being built you have to create a node that asks periodically for that transform, store it in some place, and publish all the stored points as a path in a given topic (you decide the name).
Key point here is to understand the difference between 'tf transform' and 'topic'. Gmapping publishes a topic named '/map' which contains the current map, but it also publishes the tf transform 'map' (to 'odom').
There is another potential problem. Getting the path in the way you described may suffer from loop closure or other adjustment of the map, which makes previously obtained poses invalid. Do you know a way to get the gmapping's current estimate of the trajectory?
Do you mean the robot pose? You can use the RobotModel display type and see where it is and for the other you could visualize the TF display type. base_link frame is where the base of your robot should be (with the map frame being the world frame).
@dejanpan how do I get the robot pose and uncertainty/covariance? How would I also do get the robot pose and uncertainty/covariance of the landmark observations in the map generated by gmapping slam?
Asked: 2012-09-26 04:12:53 -0500
Seen: 3,637 times
Last updated: Sep 26 '12
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