Re: [Paparazzi-devel] Rotorcraft AP Modes for Fixed-wing Aircraft?

[Prof. Dr.-Ing. Heinrich Warmers]

Hello Chris,
the best way for automatic start and landing is to measure the altitude with a acoustic altitude sensor (0-10m) the pressure sensor bmp085 is not the best.
The noise has a level  of up to 1 m. A more accurate sensor (24bit) is the MS5611-01BA01 (about 20 $, 14 Euro). A comparison of the sensors signals can be found here:http://www.diydrones.com/profiles/blogs/apm-2-0-release
By the ground effect  it  is difficult to use a pressure sensor.
Another way is a kalmanfilter for the altitude feedback control system. Pione has made one. We made also one based  on the work of.  Jan Wendel. Integrierte Navigationssystem page  298.  It works perfect .
Our idea is to measure the drift before each set-up. This is better since the drift is a function of the temperature. A solution for the drift  estimation  is also given in the book of  Wendel.
It is possible to fy in one altitude and to measure the drift direct (Wendel page 304). We measure the drift when we switch on the aircraft.
You can use a temperature stabile  acceleration sensor like the sca3000-d1. The  sensor BAM 180 is more accurate than the adxl345 (only 10 bit for one g).
Regards

Heinrich

Chris Wozny schrieb:

All,

I noticed that there are many rotorcraft configurations for autopilot mode. Is there anything like this for fixed-wing aircraft? I'd like to be able to hover our VTOL aircraft and maintain it's altitude with just the Aspirin IMU (v1.0) on Lisa/M (which would require some sort of reference altitude.) I'm not even sure if this is possible due to IMU drift. I realize this is a peculiar situation since our aircraft has rudder and elevons instead of a quadcopter which most people use so I doubt there's something in place for it.

Thanks,

Chris

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