Method for Estimating Canopy Thickness Using Ultrasonic Sensor Technology

Huitao Zhou, Weidong Jia, Yong Li and Mingxiong Ou
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Huitao Zhou: School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China
Weidong Jia: School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China
Yong Li: School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China
Mingxiong Ou: School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China

Agriculture, 2021, vol. 11, issue 10, 1-15

Abstract: The accurate detection of canopy characteristics is the basis of precise variable spraying. Canopy characteristics such as canopy density, thickness and volume are needed to vary the pesticide application rate and adjust the spray flow rate and air supply volume. Canopy thickness is an important canopy dimension for the calculation of tree canopy volume in pesticide variable spraying. With regard to the phenomenon of ultrasonic waves with multiple reflections and the further analysis of echo signals, we found that there is a proportional relationship between the canopy thickness and echo interval time. In this paper, we propose a method to calculate canopy thickness using echo signals that come from ultrasonic sensors. To investigate the application of this method, we conducted a set of lab-based experiments with a simulated canopy. The results show that we can accurately estimate canopy thickness when the detection distance, canopy density, and canopy thickness range between 0.5and 1.5 m, 1.2 and 1.4, and 0.3and 0.6 m, respectively. The relative error between the estimated value and actual value of the simulated canopy thickness is no higher than 8.8%. To compare our lab results with trees in the field, we measured canopy thickness from three naturally occurring Osmanthus trees ( Osmanthus fragrans Lour). The results showed that the mean relative errors of three Osmanthus trees are 19.2%, 19.4% and 18.8%, respectively. These results can be used to improve measurements for agricultural production that includes both orchards and facilities by providing a reference point for the precise application of variable spraying.

Keywords: canopy detection; ultrasonic echo signal; precision spray; canopy density; detection distance (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2021
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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