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GPS robot_localization point-to-point navigation

asked 2015-09-28 09:50:20 -0500

manuzagra gravatar image

I started to work with robot_localization package for the odometry of my robot and currently the local odometry is working good (the transform "odom -> base_link" has low error). I need to do point-to-point navigation and I would like to use the same package to get the global positioning using a GPS.

I am going to upload the launch file that I use and a bag file. Te route recorded in the bag file is a straight line facing to the south approximately, the robot did a round trip and it finished in the same place that he started, the return way was done in reverse walking ( I didn't want to turn because my model of the robot for the odometry is not appropriate for this terrain). I would be very thankful if somebody can take a look at it and say me if this is a correct configuration and the output is correct. (launch and bag )

My problem is I do not quite understand the meaning of each frame and, for example, if i want to move the robot to a desired position (latitude and longitude), I do not know the position of the goal relative to my robot. I think I could transform the goal to UTM coordinates, but even with this, I can't realize from what frame to what frame I should make the transform. My principal idea is to transform the goal position to UTM and make a frame whose parent is the UTM frame published from the robot_localization package and work with it, but this frame is very far and (I think) imprecise that I do not know if it is the correct way to deal with the package.

May somebody explain the frames of this package and how could I use them to naviagete with my GPS? I would need the relative position of the goal refered to the position of the robot or the global position of both, robot and goal.

Thank you very much in advance.

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answered 2015-10-01 13:56:03 -0500

Tom Moore gravatar image

updated 2015-10-01 13:56:35 -0500

The three primary coordinate frames are described here. I haven't looked too deeply, but from a cursory glance at your launch file, this looks fine.

In addition to those frames, when you use navsat_transform_node, you get a transform (in your case) from map->utm. If you want to issue a goal in the global frame, you need to first convert your lat/lon into UTM coordinates (there's a header in robot_localization that exposes this functionality), and then use the map->utm transform to transform that UTM position into your robot's world frame. You can then send that goal to your planner.

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Thank you very much, I did esactly that and it is very unstable (in altitude, I don't know why utm frame is gloiung some kilometres down the earth) and not very precise (map goes far from odom even when the robot is static). I think my problem are my GPS, I am using the GPS of a movile and a tablet.

manuzagra gravatar image manuzagra  ( 2015-10-02 04:55:09 -0500 )edit

Any chance you get record a bag file that just has your sensor data? In other words, don't run any nodes in robot_localization. It's a bit of a hassle to filter out all the topics, especially when there are a lot of input sources and transforms. Drive the robot around a bit too, if you can, please.

Tom Moore gravatar image Tom Moore  ( 2015-10-06 08:56:25 -0500 )edit

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Asked: 2015-09-28 09:50:20 -0500

Seen: 1,532 times

Last updated: Oct 01 '15