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Transform [sender=unknown_publisher]Unknown reason for transform failure

asked 2021-10-12 20:46:56 -0500

frge gravatar image

updated 2021-10-13 01:42:10 -0500

gvdhoorn gravatar image

I have a Linorobot running on a Raspeberry pi 4 and ROS 18.04 and a YDlidar.

It has been working without this problem for many months. I have not changed anything and this problem appeared in RVIZ a few day ago.

I have looked at the previous answers to this question but they do not apply to my case since my tf tree seems ok.

See the image below.

image description

When i echo the transform from /laser to /map after two tries I get the transform echoed nicely

$ rosrun tf tf_echo /laser /map
Failure at 1634088802.435207342
Exception thrown:Lookup would require extrapolation into the past.  Requested time 1634088802.397446394 but the earliest data is at time 1634088802.807524000, when looking up transform from frame [map] to frame [laser]
The current list of frames is:
Frame base_link exists with parent base_footprint.
Frame base_footprint exists with parent odom.
Frame imu_link exists with parent base_link.
Frame laser exists with parent base_link.
Frame odom exists with parent map.
Frame caster_left_link exists with parent base_link.
Frame caster_right_link exists with parent base_link.
Frame wheel_left_link exists with parent base_link.
Frame wheel_right_link exists with parent base_link.

Failure at 1634088802.435545412
Exception thrown:Lookup would require extrapolation into the past.  Requested time 1634088802.397446394 but the earliest data is at time 1634088802.807524000, when looking up transform from frame [map] to frame [laser]
The current list of frames is:
Frame base_link exists with parent base_footprint.
Frame base_footprint exists with parent odom.
Frame imu_link exists with parent base_link.
Frame laser exists with parent base_link.
Frame odom exists with parent map.
Frame caster_left_link exists with parent base_link.
Frame caster_right_link exists with parent base_link.
Frame wheel_left_link exists with parent base_link.
Frame wheel_right_link exists with parent base_link.

At time 1634088803.397
- Translation: [-0.358, 1.633, -0.180]
- Rotation: in Quaternion [0.000, 0.000, 0.977, -0.212]
            in RPY (radian) [0.000, 0.000, -2.715]
            in RPY (degree) [0.000, 0.000, -155.535]
At time 1634088804.397
- Translation: [-0.356, 1.634, -0.180]
- Rotation: in Quaternion [0.000, 0.000, 0.977, -0.211]
            in RPY (radian) [0.000, 0.000, -2.716]
            in RPY (degree) [0.000, 0.000, -155.601]
At time 1634088805.397
- Translation: [-0.353, 1.634, -0.180]
- Rotation: in Quaternion [0.000, 0.000, 0.978, -0.210]
            in RPY (radian) [0.000, 0.000, -2.717]
            in RPY (degree) [0.000, 0.000, -155.700]
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Comments

Is this a multi-host ROS application? If it is, clocks may have drifted between the hosts publishing and subscribing. Especially with TF, that can cause the problems you describe.

gvdhoorn gravatar image gvdhoorn  ( 2021-10-13 01:43:03 -0500 )edit

In principle this should not be the issue. I have an ntp server in the mobile robot and chrony in the remote pc with rviz. If i check the synchronicity it is looking ok see below

chronyc tracking
Reference ID    : D8C59C53 (ntp.nyy.ca)
Stratum         : 2
Ref time (UTC)  : Wed Oct 13 19:31:41 2021
System time     : 0.000142170 seconds slow of NTP time
Last offset     : -0.000099168 seconds
RMS offset      : 0.212730974 seconds
Frequency       : 25.788 ppm slow
Residual freq   : -0.240 ppm
Skew            : 2.451 ppm
Root delay      : 0.051655117 seconds
Root dispersion : 0.015191648 seconds
Update interval : 64.4 seconds
Leap status     : Normal

As an additional point, if i add a screen to the mobile robot and also run RVIZ on this unique machine i still have the problem.

frge gravatar image frge  ( 2021-10-13 18:14:09 -0500 )edit

Well it was one thing to check. I did not suggest it would be the one-and-only cause.

gvdhoorn gravatar image gvdhoorn  ( 2021-10-14 02:19:21 -0500 )edit

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answered 2021-10-15 16:31:02 -0500

frge gravatar image

I have finnaly solved it by simply installing the new version of the Ydlidar driver for ros (ydlidar_ros package ) for some unknown reason the old version package ( ydlidar ) was not working well anymore.

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Asked: 2021-10-12 20:46:56 -0500

Seen: 108 times

Last updated: Oct 15 '21