Re: [Paparazzi-devel] Lisa/M v2 +Aspirin IMU loss

[alonso acuña]

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> 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)

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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---
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 [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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