|
| From: | Hector Garcia de Marina |
| Subject: | Re: [Paparazzi-devel] Lisa/M v2 +Aspirin IMU loss [SOLVED] |
| Date: | Tue, 30 Sep 2014 10:04:04 +0200 |
Yes, this would explain that the values of two sensors fail. But the role of the light still seems important. Have you ever used the Aspirin without any cover or package in open air? (In our lab everything works fine.)
Balazs
2014.09.30. 9:44 keltezéssel, Hector Garcia de Marina írta:
Hi Balazs,
I do not have such problem with my aspirin IMU, and I guess nobody here,
first time I hear something like that.
In my experience it sounds more a communications problem between the
micro and the IMU (SW or HW).
On Tue, Sep 30, 2014 at 9:14 AM, Balazs GATI <address@hidden<mailto:address@hidden>> wrote:
Hi,
I don't really know which sensor fails. We draw the conclusion based
on a test yesterday: The Lisa/M module with Aspirin was installed in
an airframe and it was covered with a dark transparent cover. We
placed the airframe in the shadow and powered up the Lisa. We
observed the IMU_MAG_RAW, IMU_GYRO_RAW, IMU_ACCEL_RAW messages with
the Real-Time Plotter. The PFD and the messages showed normal
values. If we directed the sunlight to the lisa with a mirror, all
of the observed IMU messages (MAG, ACCEL, GYRO) became zeros in the
same time. If we stopped mirroring the sunlight, the messages turned
back to normal values. It is a strange experience, and far from the
allday electronic problems, but we can explain it only with the
sensitivity of the module to the light.
We have an other Lisa/M module. We didn't conducted this particular
test with this module, but in previous tests it showed very similar
behavior to the one in the test above. Both Lisa/M (with Aspirin)
was purchased by Transition Robotics.
I don't know how can I identify more precisely the origin of the
problem since we don't have any test equippment and knowledge to go
more into the details.
If you could confirm our conclusion, I would place a warning on the
Lisa/M and the Aspirin IMU section in the Wiki.
Regards,
Balazs
2014.09.30. 1:17 keltezéssel, alonso acuña írta:
Hello. Which of the sensors have this problem? Have you noticed
that
the horizon slowly keeps accumulating an error and then after
some time
in the ground fixes itself or does it really go crazy and does
not fix
itself?
On Mon, Sep 29, 2014 at 8:30 AM, Balazs GATI <address@hidden
<mailto:address@hidden>___________________________________________________<mailto:address@hidden <mailto:address@hidden>>> wrote:
Hi,
after days of bugging we identified the cause:
the Aspirin IMU is sensitive to light!
Not to the heating effect of direct sunlight, but even the
ambient
light on a cloudy day.
Regards,
Balazs
2014.09.18. 21:41 keltezéssel, Balázs GÁTI írta:
Hi,
thank you for the ideas! I don't think that the
sunlight caused the
phenomena, because the hardware never was exposed to
direct sunlight
(8/8 cloud coverage) and in addition our Aspirin IMU is
placed
directly
on the bottom side of the Lisa module.
I would be eased if somebody could report similar
experience by
high sun
activity, because on Sept. 12th, a CME hit Earth's
magnetic field,
igniting the most intense geomagnetic storm of the year.
(spaceweather.com <http://spaceweather.com>
<http://spaceweather.com>)
If no similar feedback, then we should conduct further
detailed
analysis
to find the ghost hidden in the system. :)
Regards,
Balazs
2014-09-18 21:05 időpontban Prof. Dr.-Ing. Heinrich
Warmers ezt
írta:
Hi,
the pressure sensor reacts of sun light.
Is that the problem?
You have to cover them in same foam.
Is the IMU connected separate with same wires?
The 168MHz prevent sometimes well GPS signals.
Therefore it is always a good way to make a shield
of metal
and use ferrite rings on all wires from and to the
autopilot.
Sometimes the sensor element mpu6000 is defect.
Regards Heinrich
Balazs GATI schrieb:
Hi all,
yesterday we experienced the total loss of attitude
calculation of a
Lisa/M v2 (quadshot) with Aspirin IMU in open
air. (I
mean the
artificial horizon went wild after we left the
building.) Fortunately
we didnt want to fly, but test the GPS. Finally
we could
identify the
problem: the IMU worked only if we provided
some kind of
physical
cover to the module. Steel and aluminium sheet,
thick
paper worked.
(80g/m2 copy paper and pure hand don't.) We could
explain the
phenomen with the increased sun activity or
with some
strange failure
in grounding.
Have you got similar experience in the last few
days?
Regards,
Balazs
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associate professor
Department of Aeronautics, Naval Architecture and Railway
Vehicles
Budapest University of Technology and Economics
Address: Budapest
Stoczek u 6. J. ép. 423
1111
Tel: +(36)-1-463-1960 [1]
Fax: +(36)-1-463-3080 [2]
Homepage: http://vrht.bme.hu/ [3]
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Balazs GATI, PhD
associate professor
Department of Aeronautics, Naval Architecture and
Railway Vehicles
Budapest University of Technology and Economics
Address: Budapest
Stoczek u 6. J. ép. 423
1111
Tel: +(36)-1-463-1960
Fax: +(36)-1-463-3080
Homepage: http://vrht.bme.hu/
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associate professor
Department of Aeronautics, Naval Architecture and Railway Vehicles
Budapest University of Technology and Economics
Address: Budapest
Stoczek u 6. J. ép. 423
1111
Tel: +(36)-1-463-1960
Fax: +(36)-1-463-3080
Homepage: http://vrht.bme.hu/
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Balazs GATI, PhD
associate professor
Department of Aeronautics, Naval Architecture and Railway Vehicles
Budapest University of Technology and Economics
Address: Budapest
Stoczek u 6. J. ép. 423
1111
Tel: +(36)-1-463-1960
Fax: +(36)-1-463-3080
Homepage: http://vrht.bme.hu/
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