Bugfix: Desired Frequency for hokuyo_node is fixed to 40Hz

[Ingo Kresse]

Hi everybody,

I was putting some Hokuyo URG04LX lasers to work with ROS and fixed a
small glitch in the diagnostics system in the process.

I tried to create a ticket in the Trac System but it refused with:

Trac Error
Submission rejected as potential spam

Any hint what I was missing? The settings were:

Name: Ingo Kresse (kresse-xrfDFxQfymSzQB+***@public.gmane.org)
Priority: trivial
Component: ros
Type: defect

all the rest was empty, except the summary, description and the name.

I attached the patch to this mail, together with the bug description
and one other minor issue regarding diagnostics.

The patches are against the SVN repository from today.

Best regards,
Ingo Kresse


---

Bug Description:

The driver for the Hokuyo laser range scanner sends a DiagnosticMessage,
reporting (amongst other things) the actual and desired frequency of
laser scans.

Currently the desired frequency in this message is hard coded to 40Hz,
so for a URG-04LX (working at 10Hz) the driver reports an error (but
works fine otherwise).

Attached is a patch which makes the driver use the information that it
obtained from the laser.

---

One other (minor) issue: The frequency reported using DiagnosticUpdater
was always too high by 1 because the update interval was almost always
one iteration longer than one second (one second is the desired
diagnostic message period). However for calculating the frequency the
desired period (1.0 seconds) is used via DiagnosticUpdater::getPeriod().

How about if this method returns the time that has actually passed? We
would get much better measurements.

I did a grep over the personalrobots tree, and getPeriod() was only used
in this same way to compute a frequency. A proposal for a patch is
attached.

[Blaise Gassend]

Hi Ingo,

Thanks for the patch. I'm putting it on my TODO list.

For the frequency diagnostic question, I am currently in the process of
migrating code to use an improved frequency diagnostic that is located
in the diagnostic_updater. Look at FrequencyStatus
include/diagnostic_updater/update_functions.h

For now I am building some infrastructure (such as FrequencyStatus) that
I will then be pushing to all the other drivers. But I'm not expecting
this to be ready for a couple of months at least.

Cheers,
Blaise

Post by Ingo Kresse
Hi everybody,
I was putting some Hokuyo URG04LX lasers to work with ROS and fixed a
small glitch in the diagnostics system in the process.
Trac Error
Submission rejected as potential spam
Priority: trivial
Component: ros
Type: defect
all the rest was empty, except the summary, description and the name.
I attached the patch to this mail, together with the bug description
and one other minor issue regarding diagnostics.
The patches are against the SVN repository from today.
Best regards,
Ingo Kresse
---
The driver for the Hokuyo laser range scanner sends a DiagnosticMessage,
reporting (amongst other things) the actual and desired frequency of
laser scans.
Currently the desired frequency in this message is hard coded to 40Hz,
so for a URG-04LX (working at 10Hz) the driver reports an error (but
works fine otherwise).
Attached is a patch which makes the driver use the information that it
obtained from the laser.
---
One other (minor) issue: The frequency reported using DiagnosticUpdater
was always too high by 1 because the update interval was almost always
one iteration longer than one second (one second is the desired
diagnostic message period). However for calculating the frequency the
desired period (1.0 seconds) is used via DiagnosticUpdater::getPeriod().
How about if this method returns the time that has actually passed? We
would get much better measurements.
I did a grep over the personalrobots tree, and getPeriod() was only used
in this same way to compute a frequency. A proposal for a patch is
attached.
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[Ingo Kresse]

Hi Blaise,

thank you for looking at the patches.

Wow this FrequencyStatus class looks really nice. Cool thing!


Cheers,
Ingo

Post by Blaise Gassend
Hi Ingo,
Thanks for the patch. I'm putting it on my TODO list.
For the frequency diagnostic question, I am currently in the process of
migrating code to use an improved frequency diagnostic that is located
in the diagnostic_updater. Look at FrequencyStatus
include/diagnostic_updater/update_functions.h
For now I am building some infrastructure (such as FrequencyStatus) that
I will then be pushing to all the other drivers. But I'm not expecting
this to be ready for a couple of months at least.
Cheers,
Blaise

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