DiagnosedPublisher window size seems wrong. [closed]

asked 2013-11-26 04:40:55 -0500

dornhege gravatar image

I'm not sure what's going on here. I have a DiagnosedPublisher (on Groovy) created like this:

diagnosticPub_ = new diagnostic_updater::DiagnosedPublisher<sensor_msgs::LaserScan>(pub_, diagnostics_,
      // frequency should be target +- 10%.
      diagnostic_updater::FrequencyStatusParam(&expectedFrequency_, &expectedFrequency_, 0.1, 10),
      // timestamp delta can be from 0.0 to 1.3x what it ideally is.
      diagnostic_updater::TimeStampStatusParam(-1, 1.3 * 1.0/expectedFrequency_));

Here, expectedFrequency_ is 15.0. When I check the diagnostics in rqt_robot_monitor I get the following:

Events in window: 153
Events since startup: 5945
Duration of window (s): 10.200392
Actual frequency (Hz): 14.999424
Target frequency (Hz): 15.000000
Minimum acceptable frequency (Hz): 13.500000
Maximum acceptable frequency (Hz): 16.500000
Earliest timestamp delay:: 0.051229
Latest timestamp delay:: 0.051298
Earliest acceptable timestamp delay:: -1.000000
Latest acceptable timestamp delay:: 0.086667
Late diagnostic update count:: 0
Early diagnostic update count:: 0
Zero seen diagnostic update count:: 0

According to the documentation (and actually also from what I can see in the code that is linked there) the last parameter to FrequencyStatusParam should be the window size in number of events. So with 15Hz frequency, I'd expect roughly a window length of 0.66s with 10 events. However, I'm getting a duration of the window of 10s and 10 * 15Hz = 150 events in a window.

I can't really explain what's going on here. Am I setting this up somewhere wrongly or is this functioning as intended? The behavior seems to match those observations. If I change the window size to e.g. 7, I get a 7s window. When I unplug and re-plug the device it also takes about that long until diagnostics goes back to green.

edit retag flag offensive reopen merge delete

Closed for the following reason question is not relevant or outdated by dornhege
close date 2015-06-25 12:05:06.857179