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Daniel Wee
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Tuning ArduIMU
Replied Apr 16
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Get the ArduIMU+ V2. Load up arduimu.pde and the rest of the files will load automatically. The GPS while not absolutely necessary, supposedly helps with centripetal force corrections in dynamic situations. It all depends on the type of application…
I have done quite a bit of testing with the IMU as well and what you experience is to be expected due to the code. There are several issues with the IMU code as it is. Firstly, the accelerometer needs to be properly calibrated. The default code assu…
If you see one of my previous post you will see that the noise is more important on axis X for the gyros but I don't know if it is a gyro problem of if my "noise generator" generates more noise in this axis.
On the DCM code I use I took 16 samples…
Is the drift constant and does vibration affect the amount of drift?
In my own testing I have found that many gyros exhibit a rather peculiar behaviour in the presence of vibrations - that is the bias induced by vibrations is non-random. This means…
ArduIMU 2+ doesn't have the high pass filter.
Do you use an oversampling error? or any averaging? Because I can't remove the yaw drift. Even just after the startup (after gyro offset calibration) the yaw is drifting (and other angles if I remove th…
Actually, it is the white noise that has that standard deviation. The bias instability looks invisible at that time scale, at least to me.
/me reads board schematic
Wait a minute - the ArduIMU+ has the high pass filters installed? That kills the g…
With the imu at 30cm from a motor (just laying on the same piece of wood) (same units)
Hi,
I attached data. It was taken at ground and it is the sum of 16 samples (there is bad data sometimes (29824 30335 -26497 -29568 -16261 -29308) due to serial reading errors so you should remove it). It was recorded "in real time" so at around 15…
Can you provide the data stream from the first graph, as a CSV file or equivalent? What are the units on your axes? Is this plot in-flight, or at rest?
I am only interested in roll and pitch. Yaw if totally unimportant to me.
Is that graph from the ArduIMU? The noise level looks about right and is comparable to my own test samples.
While the magnitude of the noise is 1-degree/s for 10-bits, you h…
I made some experiments last week. This graph shows the sum of 16 gyro samples [url=http://i.imagehost.org/view/0948/gyros][img]http://i.imagehost.org/0948/gyros.jpg[/img][/url]
As you can see there is a lot of noise. If you right shift it 4 times,…
Loris,
Do you happen to have any test data that can put some numbers to this? I am hoping that the noise is Gaussian in nature and will be good enough for the gyro to hold an angle for up to 15 to 20 seconds. I think that's more than reasonable. St…
Hi,
In submersibles they know their speed. There are too much noise on gyros and accelerometers to estimate the speed. Even in commercial IMUs it is impossible.
If you want to make long turns you will need a speed estimation. For short turns maybe…
I am aware of that, but as I said before - the idea is for a purely inertial solution. Typically, in a situation like this, an estimator would rely on the gyro data more until the accelerometer becomes reliable again. This is what the Accel_weight s…
Hi,
You need a speed estimation to remove centripetal acceleration. If you don't have a GPS you can add a pitot tube or simply estimate the speed with the throttle. That is what I made on a flying wing and it works fine.
Loris
Hmm... that's what I was hoping to avoid. I'm trying for the best possible purely inertial solution. What I am doing now is to improve the accelerometer de-weighting by calibrating the accelerometer more precisely and also making the de-weight expon…
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