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

[Christophe De Wagter]

When possible we put the battery + autopilot + all weight we can find that needs to fly on 1 piece of wood, which is mounted on the fuselage using 4 small corners of foam.

The best results are in a combination of both mechanical damping and software filtering. Please note these are NOT equivalent. E.g. in your plots the bias of the gyro seems to change significantly at certain throttle settings (which is to be expected and can not be undone with filtering afterwards). And also note that a low-pass filter on the gyroscopes is almost never useful.

The smaller the weight, the looser the dampers you need. E.g. to dampen a lisa-m board four pieces of 4x4x10 milimeter of packing-foam in the 4 corners are probably stiff enough.

-Christophe 

On Fri, Feb 24, 2012 at 9:29 AM, Chris Wozny <address@hidden> wrote:

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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