Testing Accuracy of Long-Range Ultrasonic Sensors for Olive Tree Canopy Measurements
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Author
Gamarra-Diezma, Juan Luis
Miranda Fuentes, Antonio
Llorens, Jordi
Cuenca, Andrés
Blanco Roldán, Gregorio L.
Rodríguez Lizana, Antonio
Publisher
MDPIDate
2015Subject
Ultrasonic sensorCanopy characterization
Olive tree
Sensor accuracy
Sensor interference
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Show full item recordAbstract
Ultrasonic sensors are often used to adjust spray volume by allowing the
calculation of the crown volume of tree crops. The special conditions of the olive tree require
the use of long-range sensors, which are less accurate and faster than the most commonly
used sensors. The main objectives of the study were to determine the suitability of the sensor
in terms of sound cone determination, angle errors, crosstalk errors and field measurements.
Different laboratory tests were performed to check the suitability of a commercial long-range
ultrasonic sensor, as were the experimental determination of the sound cone diameter at
several distances for several target materials, the determination of the influence of the angle
of incidence of the sound wave on the target and distance on the accuracy of measurements
for several materials and the determination of the importance of the errors due to interference
between sensors for different sensor spacings and distances for two different materials.
Furthermore, sensor accuracy was tested under real field conditions. The results show that
the studied sensor is appropriate for olive trees because the sound cone is narrower for an
olive tree than for the other studied materials, the olive tree canopy does not have a large
influence on the sensor accuracy with respect to distance and angle, the interference errors
are insignificant for high sensor spacings and the sensor’s field distance measurements were
deemed sufficiently accurate.