Re: [Paparazzi-devel] Lisa/M Aspirin IMU Vibration Problems

[Prof. Dr.-Ing. Heinrich Warmers]

Hi,
we have found comparable  values in our analogue IMU flying quadrocopters.
Since we use a complementary filter, that has a structure of a proportional integral feedback control system it will help to low pass filtering the accelerator values.
In analogue IMUs a low pass filter in the range of  10 to 30 Hz works fine.
By the way perhaps it is a aliasing  effect to by mixing the 500 Hz working frequency with the vibrations.
If this is true the error is a structural problem of the digital sensor in combination with the paparazzi software structure.
In my quad with the DCM i measure the acceleration only with 50 Hz and the rate with 200 Hz.
The basic stabilization uses not the angle only the rates.
Therefore the DCM is only ruining all 20ms.
It may be help if you cut the values to +-15 to 20 m/(s*s).
Thanks for the documentation.

Heinrich



Chris Wozny schrieb:

All,

I'm running into enormous issues from throttle vibrations. After
looking at the data from one of our flight tests, there's a very high
correlation between the motor vibrations and the noise in our IMU
readings. I've included plots and also ranges below. Most of the
values below should be reading 0, but instead there is substantial
deviation. How have people damped their vibrations in extremely tight
space or seen this much deviation in sensor data? I know that there's
code for low pass filtering the gyro values, but is there something
for accelerometers as well with int_cmpl_quat?

gp_range: -133.0658 to 139.7247
gq_range: -210.5803 to 228.9202
gr_range: -107.8851 to 109.6058
ax_range: -22.4756 to 44.2783
ay_range: -18.2686 to 33.1533
az_range: -55.9863 to 35.9473
phi_range: -10.0023 to 35.5467
psi_range: -18.9091 to 10.1885
theta_range: -18.1581 to 41.1144

- Chris
  

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