UAV Leaf Area Index Monitoring for Winter Wheat Drought

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Solution Overview

Problem

Current methods for monitoring drought levels in winter wheat are either labor-intensive and lack spatial representativeness or suffer from data loss and low spatial resolution, making it difficult to accurately and efficiently assess irrigation needs at a regional scale.

Innovation Solution

A rapid UAV-based monitoring method using LAI thresholds, involving multispectral image data acquisition, vegetation index calculation, and regression equation construction to invert LAI values, with calibrated thresholds for different drought levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional manual observation methods are used to monitor drought levels, then labor intensity and time consumption increase, but measurement precision and spatial representativeness remain insufficient

Engineering Contradiction:
Improvedrought level detection accuracyVSAvoidtime consumption for manual observation
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces manual mechanical observation with UAV-based remote sensing technology. The UAV captures multispectral images of winter wheat fields, and vegetation indices (NDVI, DVI, RVI, EVI, OSAVI, TCARI) are calculated to invert LAI values, automatically identifying drought levels without human intervention in the field.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a virtual copy of the wheat field conditions through remote sensing imaging. Instead of physically measuring each plant, the system captures optical representations (multispectral images) and processes them to derive LAI values that represent the actual physiological state of the crops across the entire field.

Inventive Principle:
Principle #26Copying

2Measurement precision

If soil moisture monitoring stations are deployed to capture spatial characteristics, then measurement precision improves, but device complexity and cost increase

Engineering Contradiction:
Improvespatial representation of droughtVSAvoiddensity of observation stations
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The UAV-based remote sensing system serves multiple functions simultaneously: it captures spatial distribution of drought conditions, monitors temporal changes, provides high-resolution data across the entire field, and eliminates the need for deploying multiple physical monitoring stations. A single UAV mission replaces numerous fixed stations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces the physical infrastructure of soil moisture monitoring stations with a mobile UAV platform that carries remote sensing equipment. This substitution eliminates the need for permanent installations across the field while achieving comparable or superior spatial coverage.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If remote sensing technology is used for drought monitoring, then productivity and coverage improve, but measurement precision decreases due to data loss and low spatial resolution

Engineering Contradiction:
Improvemonitoring efficiency and coverageVSAvoidspatial resolution of drought data
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent employs dynamic LAI thresholds that adapt to different growth stages of winter wheat. Instead of using fixed thresholds, the system calibrates stage-specific thresholds (jointing-Heading: 2.3-4.2, Heading-Filling: 3.2-5.17, Filling-Maturity: 2.8-4.74) to maintain measurement precision while achieving broad spatial coverage through UAV remote sensing.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the monitoring parameter from direct soil moisture measurement to LAI inversion based on vegetation indices. This parameter transformation enables the system to capture drought stress effects on plant physiology (leaf area reduction) with high precision while maintaining the productivity advantages of remote sensing technology.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If frequent UAV monitoring is conducted to capture high-frequency agricultural information, then productivity and temporal resolution improve, but use of energy and operational cost increase

Engineering Contradiction:
Improvetemporal frequency of monitoringVSAvoidenergy consumption of UAV operations
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic UAV monitoring scheduled according to winter wheat growth stages rather than continuous operation. Monitoring is conducted at key developmental phases (jointing, heading, filling, maturity) when drought stress impacts are most critical, optimizing energy use while capturing essential temporal variations in drought conditions.

Inventive Principle:
Principle #19Periodic action

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

Enables high-accuracy, flexible, and rapid drought level identification in winter wheat, enhancing precision agriculture irrigation by providing real-time drought severity assessment across various growth stages.

Implementation Method 1

UAV-based low-altitude remote sensing technology enables rapid and convenient monitoring services for agricultural fields

Methodology Applied
Scientific EffectRemote sensing:

Implementation Method 2

acquiring multispectral image data using UAV-based multi-payload low-altitude remote sensing technology

Methodology Applied
Scientific EffectMultispectral imaging:

Data Source

PatentUS12494057B2Rapid drought monitoring and identification method for winter wheat based on UAV measurements of leaf area index
Publication Date: 2025.12.09 CHINA INST OF WATER RESOURCES & HYDROPOWER RES
  • US12494057B2 patent drawing
  • US12494057B2 patent drawing
  • US12494057B2 patent drawing

AI summary

A rapid monitoring and identification method for winter wheat drought levels includes: 1) obtaining multispectral images and ground-measured LAI through UAV-based multi-payload low-altitude remote sensing technology, and calculating vegetation indices such as Normalized Difference Vegetation Index (NDVI), Difference Vegetation Index (DVI), Ratio Vegetation Index (RVI), Enhanced Vegetation Index (EVI), Optimized soil adjusted vegetation index (OSAVI) and Transformed Chlorophyll Absorption Reflectance Index; 2) establishing regression equations between the calculated vegetation indices and measured LAI for different growth stages, and selecting the optimal model equation for each growth stage; 3) using the optimal model equation to invert the LAI of winter wheat at various growth stages, and calibrating the LAI thresholds for different drought stress levels; 4) acquiring the multispectral images of target plot through real-time monitoring, calculating the required vegetation indices, inverting to obtain the LAI value, and comparing it with the threshold to determine the current drought stress level.