TITLE:
Development and Evaluation of an Optical Sensing System for Detection of Herbicide Spray Droplets
AUTHORS:
Yanbo Huang, Wei Ma, Daniel Fisher
KEYWORDS:
Near Infrared (NIR) Sensor, Spray Drift, Droplet Detection, Plant Protection
JOURNAL NAME:
Advances in Internet of Things,
Vol.11 No.1,
January
21,
2021
ABSTRACT: Real time monitoring of herbicide spray droplet drift is important for
crop production management and environmental protection. Existing spray droplet
drift detection methods, such as water-sensitive paper and tracers of
fluorescence and Rubidium chloride, are time-consuming and laborious, and the
accuracies are not high in general. Also, the tracer methods indirectly
quantify the spray deposition from the concentration of the tracer and may
change the drift characteristics of the sprayed herbicides. In this study, a
new optical sensor system was developed to directly detect the spray droplets
without the need to add any tracer in the spray liquid. The system was
prototyped using a single broadband programmable LED light source and a near
infrared sensor containing 6 broadband spectral detectors at 610, 680, 730,
760, 810, and 860 nm to build a detection system for monitoring and analysis of
herbicide spray droplet drift. A rotatory structure driven by a stepper motor
in the system was created to shift the droplet capture line going under the
optical sensor to measure and collect the spectral signals that reflect spray
drift droplets along the line. The system prototype was tested for detection of
small (Very Fine and Fine), medium (Medium), and large (Coarse) droplets within
the droplet classifications of the American Society of Agricultural and
Biological Engineers. Laboratory testing results indicated that the system
could detect the droplets of different sizes and determine the droplet
positions on the droplet capture line with 100% accuracy at the wavelength of
610 nm selected from the 6 bands to detect the droplets.