Plant Reflectance Sensing with Modulated Light Burst Suppression
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Solution Overview
Problem
Current methods for determining plant status, such as biomass and nitrogen uptake, are limited by reliance on ambient light conditions and lack of efficient suppression of ambient light, which affects accuracy and thermal load.
Innovation Solution
A system utilizing a light transmitter that sends modulated bursts of broadband light to plants, allowing for ambient light suppression and high illumination while reducing thermal load, using multiple transmitter and receiver channels with adjustable wavelengths and optics for precise light measurement and processing, including AC-coupled current to voltage conversion and phase rectification to isolate plant reflectance signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If continuous broad band illumination is transmitted to plants, then high illumination intensity is achieved for accurate measurement, but thermal load of the light transmitter increases
Solution Approach 1:
The light transmitter operates in periodic bursts rather than continuously, transmitting broad band illumination in intervals. This periodic operation allows the system to achieve high illumination intensity during measurement periods while reducing average thermal load on the transmitter, resolving the contradiction between maintaining high illumination and managing thermal effects.
2Ease of operation
If ambient light is included in measurements, then measurement can be performed under natural conditions, but measurement precision of plant reflectance decreases
Solution Approach 1:
The system extracts and separates the plant reflectance signal from the ambient light background by using modulated broad band illumination and selective receiver channels. The receiver is configured to detect only the modulated signal component from the transmitter, effectively taking out the plant-specific signal while rejecting unmodulated ambient light, thus maintaining measurement precision under natural conditions.
Solution Approach 2:
By using modulated periodic illumination, the system creates a time-varying signal that can be distinguished from steady ambient light. The receiver synchronizes with the modulation frequency to detect only the periodic component, enabling precise plant reflectance measurement while operating in natural ambient light conditions.
3Adaptability or versatility
If multiple transmitter channels with different wavelengths are used, then spectral coverage is improved for comprehensive plant status determination, but device complexity increases
Solution Approach 1:
The broad band illumination is segmented into multiple wavelength bands using separate transmitter channels, each covering a specific spectral region. This segmentation allows comprehensive spectral coverage for determining various plant status parameters while managing device complexity by organizing the system into modular wavelength-specific channels with dedicated receiver channels for each band.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively determines plant status by suppressing ambient light and achieving high illumination with reduced thermal load, enabling accurate measurement of chlorophyll content, biomass, and nitrogen uptake, and can be used to control variable rate applicators like fertilizer systems.
Implementation Method 1
the light transmitter is arranged for transmitting the light in modulated bursts
Implementation Method 2
The chlorophyll content is usually determined by means of optical reflectance measurements
Implementation Method 3
Each receiver channel includes an AC-coupled current to voltage (AC-CV) converter
Data Source
AI summary
The invention relates to a system and method for determining a status of plants. The system includes a light transmitter arranged for providing broad band illumination to one or more plants. The system includes a light receiver including a plurality of receiver channels, the receiver channels arranged for receiving light from said one or more plants in mutually different wavelength bands. The system includes a processing unit arranged for determining a status of said one or more plants on the basis of light received by the plurality of receiver channels. The transmitter may be arranged for transmitting bursts of modulated light.