What is the appropriate way to get the robot pose information from published messages?

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zheng rong

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Sep 29, 2017, 3:24:43 AM9/29/17
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Hi all,

I am trying to get the pose information (position and attitude w.r.t global map or local map) of robot from Cartographer. 
By checking the info of published topics, I found the pose info may be included in the /tf and /submap_list.
And the /tf is published by two publishers: /cartograpoher_node and /robot_state_publisher.

My questions are:
1. what is the definition of pose included in /submap_list?
2. Can base_link in /tf published by /cartographer_node be used to represent the pose of robot? 
3. How to separate the /tf published by /cartogrpher_node and /robot_state_publisher so that I can distinguish them? (I haven't dived into the code structure, so an easy way would be helpful. )

Thanks in advance.

Zheng

Damon Kohler

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Sep 29, 2017, 9:57:53 AM9/29/17
to zheng rong, google-cartographer
This is more of a generic ROS question than a Cartographer-specific question. The short answer is, you'll want to create a tf listener that computes the robot's pose for you based on what's being published to the /tf topic.

If you need more assistance with that, I suggest you reach out to http://answers.ros.org/

HTH,
Damon

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zheng rong

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Sep 29, 2017, 9:46:40 PM9/29/17
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Hi Damon,

Thanks for your help. I am trying to figure it out.
The coordinate frame tree is map-->odometry-->base-->[IMU, horizontal lidar, vertical lidar]. I read the doc-web, but I am a little confused about the odometry frame.
When running the 3d-demo, I found that the odom-frame moves little and it is always close to map-frame origin.
By my understanding the base-link can be used to represent the robot's pose w.r.t global map (starting point).
But what is the difference between odometry-frame and base-frame? What is the purpose of odometry-frame?

I am using one 3D-lidar and IMU, and the frame configuration I am using is like this:
map_frame = "map",
tracking_frame = "imu_link",
published_frame = "base_link",
odom_frame = "odom",
provide_odom_frame = true,


Thanks,
Zheng

在 2017年9月29日星期五 UTC+8下午9:57:53,Damon Kohler写道:
This is more of a generic ROS question than a Cartographer-specific question. The short answer is, you'll want to create a tf listener that computes the robot's pose for you based on what's being published to the /tf topic.

If you need more assistance with that, I suggest you reach out to http://answers.ros.org/

HTH,
Damon

On Fri, Sep 29, 2017 at 9:24 AM zheng rong <zheng....@gmail.com> wrote:
Hi all,

I am trying to get the pose information (position and attitude w.r.t global map or local map) of robot from Cartographer. 
By checking the info of published topics, I found the pose info may be included in the /tf and /submap_list.
And the /tf is published by two publishers: /cartograpoher_node and /robot_state_publisher.

My questions are:
1. what is the definition of pose included in /submap_list?
2. Can base_link in /tf published by /cartographer_node be used to represent the pose of robot? 
3. How to separate the /tf published by /cartogrpher_node and /robot_state_publisher so that I can distinguish them? (I haven't dived into the code structure, so an easy way would be helpful. )

Thanks in advance.

Zheng

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Damon Kohler

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Oct 2, 2017, 6:07:01 AM10/2/17
to zheng rong, google-cartographer
Take a look at REP 105 which goes into some detail about how map, odom, etc. are typically related to one another in ROS.

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zheng rong

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Oct 24, 2017, 10:06:41 PM10/24/17
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Thanks, Damon.

在 2017年10月2日星期一 UTC+8下午6:07:01,Damon Kohler写道:
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Damon Kohler

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Google Germany GmbH

Erika-Mann-Straße 33

80636 München


Geschäftsführer: Paul Manicle, Halimah DeLaine Prado

Registergericht und -nummer: Hamburg, HRB 86891

Sitz der Gesellschaft: Hamburg


Diese E-Mail ist vertraulich. Falls sie diese fälschlicherweise erhalten haben sollten, leiten Sie diese bitte nicht an jemand anderes weiter, löschen Sie alle Kopien und Anhänge davon und lassen Sie mich bitte wissen, dass die E-Mail an die falsche Person gesendet wurde.

    

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