Dear Heinrich
There was an other improvement we made:
At the beginning we took small air tubes made of rubber. (which were
elastic)
Then we replaced them with small tubes made of Teflon.
Reason: Every vibration can easily disturb the air pressure in a
soft tube.
I think a I2C-USB adapter will do the work:
For example: (The firs one I found)
http://www.robot-electronics.co.uk/acatalog/USB_I2C.html
http://www.robot-electronics.co.uk/htm/usb_i2c_tech.htm
I assume there isn't something in the paparazzi project at the
moment that will send pressure data continuously from the ground
station.
(Correct me if I'm wrong)
The GCS use the telemetry (e.g. Xbee) to send the instructions to
the autopilot. There must be a way to use this connection to send
the ground pressure data. Maybe a author of the GCS will give you
more detailed information about this part of the project.
If you're interested: (more about airspeed than baro pressure
measurement)
I've published the work on
http://paparazzi.enac.fr/wiki/User:Bruzzlee
Bruzzlee
Am 16.08.11 01:01, schrieb Prof. Dr.-Ing. Heinrich Warmers:
Dear Bruzzlee,
dear Christophe,
we use the static pressure of a pilot tube from the eagle TAS
interface.
The aircraft was a delta with 0.8m span. The tube was mounted in
the
front of one wing outside the propeller generated turbulence.
Holes are about 6cm away from the wing.
The sensor was far away from other electronic.
We found for our measure system used for metrology measurements
(a
small box with Tini1.3 and the sensors) a lager noise +-0.7m
compared to +-0.35m for the separation.
We flow in an altitude of 35m. The temperature did not change.
I think the most of the delta in altitude was generated by the
constant
TAS feed back control system.
The idea with a second static pressure measurement on ground is
possible but expensive (a second tiny with telemetry and pressure
sensor).
Is there any ftti chip with i2c or SPI interface?
How it is possible to send the static pressure from the ground
station
to the aircraft periodically?
Sincerely,
Heinrich
Christophe De Wagter schrieb:
Dear
Heinrich,
Where was the sensor located and in which kind of aircraft?
Did
you use a pitot+static tube or just measure the fuselage (or
wing in
case of a delta) pressure. How was the temperature change
during the
flight?
Sincerely,
-Christophe
On Mon, Aug 15, 2011 at 10:11 PM,
Prof.
Dr.-Ing. Heinrich Warmers <address@hidden>
wrote:
Hi,
today we made our first flights only with the BMP085
pressure sensor.
We made an average of 4 pressure values and send the rate
to 20
samples/s.
The altitude control system was stabile but just with an
large error
+7m -4m when flying ovals depending on the position.
After landing we had often a altitude of -1..-2m by a
flight time of
30 minutes.
Has someone an idea to get more precise results?
Regards
Heinrich
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