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Re: [Paparazzi-devel] re:RazzorIMU

From: Prof. Dr.-Ing. Heinrich Warmers
Subject: Re: [Paparazzi-devel] re:RazzorIMU
Date: Fri, 11 Feb 2011 09:09:30 +0100
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; de-DE; rv:1.4) Gecko/20030619 Netscape/7.1 (ax)

one Question, have you resoldered the Resistors from the tiny 2.11?
As for the tworg the 5V analogue inputs  have 2 resistors for a voltage divider.
You have to put away the resistor to grnd to make it possible to measure full 
range 0..3.3V and not 0..5V.
The output amplifier from the sensors can't drive the imput impedance of the 5V 


Dear Dr. Warmers,
I have finally installed Oliver's software version. I had a compiling
error related to an AHRS_ALIGNER_led and have solved it after defining
it in the makefile for my board(tiny v2.11). Now I can see the PFD running, but don't know if it moves in the usual way. It has a slow rensponse and a little oscillatory. Ana

-----Original Message-----
From: GARCIA ALVAREZ, ANA Sent: Thursday, February 10, 2011 10:58
To: 'Prof. Dr.-Ing. Heinrich Warmers'
Subject: RE: RazzorIMU

Dear Dr. Warmers,
I have been looking in this code, although I'll look again. Sorry I'm
asking too much, but am not very experienced in programming and looking
into the code is a bit hard for me. Ana

-----Original Message-----
From: Prof. Dr.-Ing. Heinrich Warmers [mailto:address@hidden Sent: Thursday, February 10, 2011 10:51
Subject: RazzorIMU


Please look in the branch
of oliver and crihstoph

Pleas note that Christop has put the imu in the opposideed direction compared to Oliver.
Olivers code is running on a tiny and chistorp on a tworg.
Regards Heinrich

Hi Ana, Hi Felix, Hi Heinrich,

the SENS values in hb_tiny_razor.xml airframe file (4096 = 12 Bit) are only set to reverse the BFP formating what ist done for rates in RATES_FLOAT_OF_BFP(gyro_float, imu.gyro); in ahrs_propagate();

/* convert bfp imu data to floating point */
RATES_FLOAT_OF_BFP(gyro_float, imu.gyro); // olri div by (1<<12)

/* unbias rate measurement */
RATES_DIFF(ahrs_float.imu_rate, gyro_float, ahrs_impl.gyro_bias);

The trick to get it work is to scale the values from deg/s to RAD/s,
see the lines below from my ahrs_propagate();.

// scale gyro adc raw to [rad/s] FIXME // olri
ahrs_float.imu_rate.p /= 61.35f;
ahrs_float.imu_rate.q /= 57.96f;
ahrs_float.imu_rate.r /= 60.10f;

The result of the that *must* give closest-by 0.0... rate on silence!

It's at the moment *impossible* to combine these 2 factors,
becourse the bias is substracted between these to steps.

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