Re: [Paparazzi-devel] New IMU in YAPA

[Heinrich Warmers]

Hello,
what is the reason for hi-end IMU's on the yapa ?
When i measure the vibrations on my multikopters i get levels of  0.4 g .
The rate sensors are not so sensible for vibrations since modern have vibrations frequencies over 20kHz..
The vibrations have most first an second orders of the revolutions of the propellers when you generate a  spectrum.
A good pressure sensor with 24 bit resolution save the problems with the altitude measurement of the GPS (Wrong values up to 80m if roll angles > 70°. are flown). When i calibrate the ID500 after power on i reach a bias value of 0.3 to 0.5 °/s with the HB-mini.
So the cheap rate sensors build not a problem. The MPU6050 cost about 7 Euros 1-2°/s  and fly quadrcooters and normal wing excellent.
The problem is the filter.  The DCM filter was the first filter in paparazzi witch estimates the centripetal forces. With this filter you can fly helixes and circles as long you want. A improvement  for implement magnetometer values and offset angles would be fine.

To make a true INS you need a FPU and a closely coupled GPS and about 3-5  years of time to write a new dissertation of sensor fusion.
And the result ?  To have true values for 20 seconds instead of 4?

Please think first on the near problems 1. save fly with a GPS lost. 2. filters for the acceleration measure values. 3. true altitude measurement without GPS 3. true airspeed measurement 4. damping the vibrations etc.

Regards

Heinrich Warmers






Mauro Garcia Acero schrieb:

Hello everyone,

 

After some discussion with TU Delft people, I will try to integrate the new ADIS16488 from Analog Devices into the YAPA in order to verify the behavior of paparazzi with a high end MEMS IMU:

 

<From the AD site>

6°/hr in-run bias stability

0.3°/√hr angular random walk

0.01% nonlinearity

 

Because this IMU communicates through SPI port, do you have any suggestion about how could I go quicker in the development of the new module? I was thinking to reuse one existing IMU module already communicating through SPI. But I have just begun to analyze the doc of the web site, so, I'm open to any kind of possibility.

 

Thanks in advance,

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