Active NIR Plant Sensing for Ambient Light Compensation
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Solution Overview
Problem
Existing plant sensors are costly, complex, and inaccurate due to fluctuations in solar radiation and external light interference, making them unsuitable for environments with varying light conditions, especially artificial lighting.
Innovation Solution
A plant sensor device that actively irradiates near-infrared light intermittently or at varying intensities, classifies and records output values during irradiation and extinction periods, and calculates leaf area index using differences in output values to suppress external light influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmitted light method using solar radiation is used to measure leaf area index, then measurement can be performed without active light source, but measurement precision deteriorates due to fluctuations in solar radiation and external light interference
Solution Approach 1:
The light source emits light periodically with alternating emission and non-emission periods. By measuring transmitted light intensity during emission periods and ambient light intensity during non-emission periods, the system can subtract ambient light effects from the transmitted light measurement, thereby eliminating external light interference and improving measurement precision and reliability
Solution Approach 2:
The system uses its own light source to illuminate the measurement target and simultaneously uses the non-emission periods to self-calibrate by measuring ambient light conditions. This self-service approach allows the system to automatically compensate for external light variations without requiring separate calibration procedures
2Measurement precision
If active light source is introduced to improve measurement precision, then external light interference is reduced, but device complexity and cost increase
Solution Approach 1:
The light source serves multiple functions: it provides illumination for transmitted light measurement, enables active optical sensing to eliminate external light interference, and during non-emission periods, allows ambient light measurement for compensation. This multi-functionality reduces the need for separate components and simplifies the overall device structure
Solution Approach 2:
The system combines the light source, transmitted light sensor, and ambient light measurement capability into a single integrated sensor device. By merging these functions into one compact unit rather than using separate instruments, the device complexity is reduced while maintaining high measurement precision
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 device provides highly accurate, low-cost measurements of leaf biomass and growth parameters by minimizing external light interference, suitable for various lighting conditions.
Implementation Method 1
a radiation sensor that is disposed on a side opposite to the light source with respect to the plant, receives transmitted light of the near-infrared light that has passed through the plant, and outputs a photoelectrically converted output value
Data Source
AI summary
A plant sensor device that suppresses the influence of external light from the surrounding environment and determine highly accurate parameters relating to the leaf biomass of a plant with a simple and low-cost configuration for quantifying the degree of plant growth, which is a plant sensor device 100, including: a light source 11 that intermittently irradiates a plant with near-infrared light (NIR); a radiation sensor 21 that is disposed on a side opposite to the light source 11 with respect to the plant, receives transmitted light of the near-infrared light that has passed through the plant, and outputs a photoelectrically converted output value; and a recording unit 31 that records the output value from the radiation sensor 21, in which the recording unit 31 records an irradiation period and an extinction period of the near-infrared light in the light source 11, and the recording unit 31 classifies output values from the radiation sensor into the following: (1) NIR output values during the irradiation period of the near-infrared light; and (2) non-irradiated output values during the extinction period of the near-infrared light; and a method for active optical sensing of plants.