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Re: [Paparazzi-devel] re: razor imu
From: |
Oliver Riesener |
Subject: |
Re: [Paparazzi-devel] re: razor imu |
Date: |
Wed, 19 Jan 2011 11:02:11 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.13) Gecko/20101208 Thunderbird/3.1.7 |
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.
I worked hard for finding out that ;-), but i didn't see the
jumping point to solve it better, i am not fimiliar with BFP.
Regards
Oliver
On 19.01.2011 09:00, Prof. Dr.-Ing. Heinrich Warmers wrote:
Hi Ana,
please make a output of the rate sensor and accelerator values.
I fond that an value of 2-3 LSB results in rolling PFD.
This is also given if , wire has broken.
Sometimes the accelerators values have an error up to 20%. when measuring g.
Regards
Heinrich
GARCIA ALVAREZ, ANA schrieb:
Hi Felix,
As Oliver said, after waiting 3minutes, the ATTITUDE message and PFD works…but
still not well.
I haven’t the right sens parameters up to now. I looked into Oliver’s ones, but
they don’t work for me(too much sensibility according to the PFD, and I have an
offset(I think) which rolls the PFD continuously). I’m trying changing the
values but I’m afraid it’s a really empiric method and don’t know if some day
it’ll work.
Are these values(sens and neutrals) the only parameters I’m supposed to touch?
I am also looking for Christoph’s values, but I haven’t found them-I think they
aren’t in an airframe file but in another one-.
Ana
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