An ultrasonic anemometer for lightweight fixed-wing UAV airspeed measurements
Publicerad
Författare
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This thesis explores the development of an ultrasonic airspeed sensor for lightweight
fixed-wing drones. The ultrasonic airspeed sensor acts as an alternative to Pitotstatic
systems, a differential pressure sensor used for obtaining airspeed data for aircraft.
The design takes inspiration from commercially available ultrasonic anemometers
and ultrasonic distance sensors.
The prototype consists of two ultrasonic transceivers facing each other at a predefined
distance. One ultrasonic transceiver will transmit a signal, while the other
will receive it. These roles will change to obtain an upstream and downstream
airspeed measurement. The system records the time of initial transmission to receiving
the signal, and by knowing the distance between the two ultrasonic sensors,
the speed of sound can be established. Many factors can influence the speed of
sound, however the only factor that has a directional component is wind. Taking
advantage of this, the influence of wind and all other atmospheric conditions on the
speed of sound can be separated.
The ultrasonic signal is processed by an analog signal conditioning circuit consisting
of amplifiers, filters and a comparator. A received ultrasonic signal peak
is detected by the transition of comparator states, which is used to determine the
transmission time. Cross-correlating upwind and downwind signal phases will determine
the indicated airspeed measurement, which requires further calibration to
obtain calibrated airspeed measurements.
Beskrivning
Ämne/nyckelord
airspeed measurements, Pitot-static systems, signal processing, ultrasonic transceivers, ultrasonic anemometers, digital signal processing, transit-time