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Delay in tf broadcaster robot_pose_ekf

asked 2013-05-30 05:09:54 -0600

jep31 gravatar image

updated 2013-05-30 23:32:47 -0600

I'm trying to run Turtlebot using a fixed Kinect in the room, but I have some Tf issues in rviz. I cannot visualize robot Tf after base_footprint but I can see the link by:

$rosrun tf view_frames

image description

$rosrun tf tf_echo /odom /base_footprint

> At time 1369922387.939
> - Translation: [0.000, 0.000, 0.000]
> - Rotation: in Quaternion [0.000, 0.000, 0.000, 1.000]
>             in RPY [0.000, -0.000, 0.000] At time 1369922388.974
> - Translation: [0.023, 0.001, 0.000]
> - Rotation: in Quaternion [0.000, 0.000, 0.070, 0.998]
>             in RPY [0.000, -0.000, 0.140] At time 1369922389.940
> - Translation: [0.023, 0.001, 0.000]
> - Rotation: in Quaternion [0.000, 0.000, 0.070, 0.998]
>             in RPY [0.000, -0.000, 0.140]

I can see some delay issues by tf_monitor: RESULTS: for all Frames

Frames: Frame: /ar_marker published by /pattern_reader Average Delay: 0.00499706 Max Delay: 0.0056474 Frame: /base_footprint published by /robot_pose_ekf Average Delay: 3415.33 Max Delay: 3415.36 Frame: /base_link published by /robot_state_publisher Average Delay: -0.486476 Max Delay: 0 Frame: /base_marker published by /baseMarker Average Delay: 0.000302851 Max Delay: 0.00233504 Frame: /camera_depth_frame published by /robot_state_publisher Average Delay: -0.486468 Max Delay: 0 Frame: /camera_depth_optical_frame published by /robot_state_publisher Average Delay: -0.486467 Max Delay: 0 Frame: /camera_link published by /robot_state_publisher Average Delay: -0.486478 Max Delay: 0 Frame: /camera_rgb_frame published by /robot_state_publisher Average Delay: -0.486466 Max Delay: 0 Frame: /camera_rgb_optical_frame published by /robot_state_publisher Average Delay: -0.486465 Max Delay: 0 Frame: /front_wheel_link published by /robot_state_publisher Average Delay: -0.486464 Max Delay: 0 Frame: /gyro_link published by /robot_state_publisher Average Delay: -0.486463 Max Delay: 0 Frame: /laser published by /robot_state_publisher Average Delay: -0.486462 Max Delay: 0 Frame: /left_cliff_sensor_link published by /robot_state_publisher Average Delay: -0.486475 Max Delay: 0 Frame: /left_wheel_link published by /robot_state_publisher Average Delay: 3414.33 Max Delay: 3414.34 Frame: /leftfront_cliff_sensor_link published by /robot_state_publisher Average Delay: -0.486473 Max Delay: 0 Frame: /odom published by /initialPose Average Delay: 0.000253598 Max Delay: 0.000583442 Frame: /openni_rgb_optical_frame published by /world_kinect_link Average Delay: -0.0998099 Max Delay: 0 Frame: /plate_0_link published by /robot_state_publisher Average Delay: -0.486461 Max Delay: 0 Frame: /plate_1_link published by /robot_state_publisher Average Delay: -0.48646 Max Delay: 0 Frame: /plate_2_link published by /robot_state_publisher Average Delay: -0.486459 Max Delay: 0 Frame: /plate_3_link published by /robot_state_publisher Average Delay: -0.486458 Max Delay: 0 Frame: /rear_wheel_link published by /robot_state_publisher Average Delay: -0.486457 Max Delay: 0 Frame: /right_cliff_sensor_link published by /robot_state_publisher Average Delay: -0.486472 Max Delay: 0 Frame: /right_wheel_link published by /robot_state_publisher Average Delay: 3414.33 Max Delay: 3414.34 Frame: /rightfront_cliff_sensor_link published by /robot_state_publisher Average Delay: -0.486471 Max Delay: 0 Frame: /spacer_0_link published by /robot_state_publisher Average Delay: -0.486456 Max Delay: 0 Frame: /spacer_1_link published by /robot_state_publisher Average Delay: -0.486455 Max Delay: 0 Frame: /spacer_2_link published by /robot_state_publisher Average Delay: -0.486454 Max Delay: 0 Frame: /spacer_3_link published by /robot_state_publisher Average Delay: -0.486453 Max Delay: 0 ...

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answered 2013-05-30 11:07:26 -0600

tfoote gravatar image

The 3000 second delta will never be transformable across with the default 10 second tf buffer.

The most common reason for this is having multiple machines which are not in sync. You should make sure that your machines are syncronized with ntp. We recommend using chrony.
There's a TurtleBot tutorial to set this up.

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Oh you are right, synchronize machines works very well. Thank you. To be sure, I execute "sudo ntpdate ntp.ubuntu.com" on both machine at the same time. What is the correct process ?

jep31 gravatar imagejep31 ( 2013-05-30 23:00:10 -0600 )edit

That command will tell your machine to sync to an external server. You don't need to run them at the same time. To keep your machines in sync persistently you should install the chrony service so it runs in the background.

tfoote gravatar imagetfoote ( 2013-05-31 07:43:04 -0600 )edit

Do I need a Internet connexion to do this ? Because now I'm working on a local network without internet connexion and the synchronization doesn't work anymore. How can I synchronize without external connexion ? EDIT: solution= ntpdate -q other_computer_ip

jep31 gravatar imagejep31 ( 2013-06-05 05:49:20 -0600 )edit

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Asked: 2013-05-30 05:09:54 -0600

Seen: 392 times

Last updated: May 30 '13