Using robot_pose_ekf output for Navigation stack

asked 2011-09-02 05:38:41 -0500

jbeck27
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updated 2011-09-02 08:22:15 -0500

8372 ●45 ●74 ●99 http://www.meloneewise.com/

I am currently working on a robot similar to a turtlebot that uses the gyro from the turtlebot and encoders for tracking movement. I setup the robot_pose_ekf to take in the data and it is working correctly. I am now confused at what to do with the output of robot_pose_ekf. It is in the format geometry_msgs/PoseStamped and the navigation stack requires nav_msgs/Odometry. I am unsure if I am heading in the right direction with this but the overall goal is to combine the gyro and the encoder readings and then send it to the nav stack. Does anyone have any ideas or suggestions?

Thanks

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answered 2011-09-02 08:21:41 -0500

mmwise

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robot_pose_ekf broadcasts the tf transform from odom_combined to base_link (odom_combined -> base_link) which amcl uses to compute the position of the robot. A good explanation of how this works can be found here: http://www.youtube.com/watch?v=C92bxCr05Gs

The turtlebot_navigation package does what you are describing. Checkout the autonomously navigating in a known map tutorial. (http://www.ros.org/wiki/turtlebot_navigation/Tutorials/Autonomously%20navigate%20in%20a%20known%20map)

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Thank you for the response. I actually had already found your videos, nice job btw. I guess a better phrasing of the question would if you run robot_pose_ekf and the nav stack is using it in the AMCL, what do you send as "odom" to the local_planner inside the navigation system?

jbeck27 ( 2011-09-02 09:05:09 -0500 )edit

in the configuration files you should see a line: <param name="odom_frame_id" value="odom_combined"/> you need to set the param to the frame you want to use. It's in the amcl_turtlebot.launch file.

mmwise ( 2011-09-02 11:07:40 -0500 )edit

That didn't solve the problem. I think I can clarify what I need now though. the robot_pose_ekf publishes a tf frame that amcl uses. What I need is some way to give the local planner the "odom" message. I am referencing the diagram in http://www.ros.org/wiki/move_base .

jbeck27 ( 2011-10-14 10:40:07 -0500 )edit

I want the combined gyro and wheel odometry to be given to the local planner. robot_pose_ekf publishes "odom_combined" that is not a nav_msgs/Odometry message. What is given to the local planner for the turtlebot?

jbeck27 ( 2011-10-14 10:42:18 -0500 )edit

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answered 2012-02-02 19:31:12 -0500

weiin
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robot_pose_ekf subscribes only to the Pose portion of odom to give the estimated pose.

whereas move_base takes only the velocity information from odom. if you look at the diagram, the "odom" message goes to the local planner which is the base_local_planner. This subscribes to odom which uses the velocity for trajectory calculations

so I don't think you can use the robot_pose_ekf output for navigation planning

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answered 2012-01-21 22:01:16 -0500

Nikhil
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Hi jbeck27 - were you able to resolve the issue? I'm also a little confused whether the local planner uses odom_combined or just odom. Since the navigation stack also works without a map, I suspect that the local planner should be using odom_combined, implying it uses the output at the geometry_msgs/PoseStamped msg in move_base. Would that be correct?

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answered 2013-03-20 16:28:17 -0500

Astronaut
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Hi I have the same issue with robot_pose_ekf. Did u already fix it? I was told that it is not a bug It is not a bug, it just doesn't take velocity directly, it takes poses. So Im bit a confuse. Any help??

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answered 2012-01-22 04:51:01 -0500

Alireza

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HI, I have the same problem with robot_pose_ekf and i don't know why they dont solve this big issue!!

Currently i am trying to write a node for converting "msgs/PoseStamped msg" of robot_pose_ekf to "nav_msgs/Odometry message". in my case i faced 2 problems about covariances of odometry message and also twist part of odometry message.

I didnt implemented this node completely but as soon as its finished i will be post the results here!