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| Titel |
Airborne meteorological measurement unit for small UAVs |
| VerfasserIn |
Norman Wildmann, Jens Bange, Aline van den Kroonenberg |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053022
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| Zusammenfassung |
| In lower-atmosphere research the atmospheric boundary layer (ABL) is of high interest
because the exchange of energy between earth surface and the atmosphere begins here. Many
of the processes and interactions in this layer are known, but not fully understood, which
makes it necessary to gain a better understanding by observing the characteristic variables of
the system.
Observing in the atmosphere can be done by means of airborne measurements. For
this purpose a UAV platform (MASC - Multi-purpose Automatic Sensor Carrier)
was developed at the University of Tübingen that is able to carry meteorological
payloads. MASC is equipped with an autopilot to be able to fly pre-defined routes
autonomously.
As the basic meteorological payload a measuring unit is designed and developed which is
capable of measuring temperature, humidity, pressure and aircraft attitude with high
resolution and precision. The unit is designed to fit on MASC, but is easily exchangeable and
does not interact with the navigation and power units of the aircraft. In this set-up the
measuring system can be used to measure vertical profiles of the ABL, as well as turbulent
flux in heat, humidity and momentum.
In detail, the system consists of meteorological sensors including a five-hole probe
connected to high precision pressure transducers, a fast response thermocouple and a fast
response humidity sensor. Additionally, to calculate position and attitude of the
aircraft, an inertial measurement unit (IMU) and a GPS receiver are installed in the
unit.
The thermocouple is designed to be able to measure temperatures in a range of
-20Â °C to 200Â °C. First tests are demonstrated that proof high sensitivity and fast
response times that allow to resolve turbulent fluctuations as fast as 20Â Hz and
more.
To measure humidity, two sensors with specified static response times of about 2Â s were
compared and shown to be able to resolve turbulent fluctuations up to 10Â Hz. Both of the
sensors are based on capacitive measuring principles.
All sensors are directly connected to a central board computer developed in cooperation
with the University of Applied Sciences Ostwestfalen-Lippe (AMOC - Aerial Meteorological
On-Board Computer). This embedded computer is equipped with two microcontrollers, a
24-bit analog-digital-converter, an SD-card and common interfaces (Analog, SPI,
CAN, Uart) for all sensors as well as additional optional periphery. An 868Â MHz
wireless module is connected to the board computer and makes it possible to send
live data to a ground station computer. On the ground station all sensor data can
be visualized and observed during the flight, making it possible to see if sensors
are functional and adapting the flight plan according to the current meteorological
situation.
All data is logged onto the sd-card at a rate of 100Hz. In post-processing, the raw sensor
data will be used to calculate turbulent flux, wind vector and precise attitude of the
UAV.
First tests and results will be presented, including vertical profiles of the ABL and power
spectrums of humidity and temperature. |
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