Mutual Inductance Soil Moisture Sensor
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Solution Overview
Problem
Existing soil moisture sensors for agriculture are not effective as they are either high power, difficult to install, and unable to accurately measure large volumes of soil without soil-specific calibration, and existing radio frequency sensing technologies are not low power and easy to install.
Innovation Solution
A soil moisture monitoring system using a device with a master and slave element configuration, employing inductance-based sensing with mutual coupling and reference inductors to measure soil moisture and temperature, transmitting data wirelessly for irrigation control, and applying temperature compensation for accurate volumetric water content determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If existing soil moisture sensors are used, then measurement capability is provided, but they consume high power and are difficult to install
Solution Approach 1:
The patent replaces complex mechanical installation systems with electromagnetic field-based sensing. The sensor uses radio frequency signals to measure soil moisture without requiring physical contact with soil particles or complex mechanical probes, thereby reducing installation complexity and power consumption.
Solution Approach 2:
The patent changes the measurement parameter from direct electrical contact methods to inductance-based electromagnetic sensing. By measuring changes in inductance caused by soil moisture content, the system achieves low-power operation and easier installation without requiring complex mechanical or electrical connections to the soil.
2Area of stationary object
If existing sensors measure large volumes of soil, then measurement coverage is improved, but soil-specific calibration is required
Solution Approach 1:
The patent creates a universal sensing mechanism that measures soil moisture across different soil types without requiring soil-specific calibration. The inductance-based measurement approach fundamentally captures the dielectric properties of water in soil, which remain consistent across different soil compositions, enabling a single device to function universally across various soil types.
Solution Approach 2:
The patent uses reference inductors that create a standardized electromagnetic field pattern, effectively copying a known reference state against which all measurements are compared. This reference-based approach eliminates the need for soil-specific calibration by providing a universal baseline for measurement across different soil conditions.
3Measurement precision
If radio frequency sensing is used, then measurement capability is provided, but power consumption is high
Solution Approach 1:
The patent employs periodic transmission of radio frequency signals rather than continuous transmission. The oscillator circuit generates RF signals at specific intervals to measure inductance changes, allowing the system to maintain measurement precision while significantly reducing average power consumption compared to continuous RF sensing.
Solution Approach 2:
The sensor utilizes the natural electromagnetic properties of the soil and reference inductors to generate measurement signals without requiring high-power external excitation. The system leverages the inherent dielectric characteristics of soil moisture to produce measurable inductance variations, reducing the need for high-power signal generation while maintaining measurement accuracy.
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 provides accurate, low-power, easy-to-install soil moisture measurement across large volumes without soil-specific calibration, with an R-squared correlation of 0.92 or better, enabling efficient irrigation management.
Implementation Method 1
a first oscillator circuit coupled with one or more reference inductors to emit a first inductance frequency; a second oscillator circuit coupled with one or more mutual inductors to emit a second inductance frequency
Implementation Method 2
one or more mutual inductors that sense soil moisture inductance in an area of soil
Data Source
AI summary
Soil moisture monitoring systems and methods for measuring mutual inductance of area of influence using radio frequency stimulus are disclosed herein. An example device includes a master element stacked vertically on top of one or more slave elements. The master element and slave elements can communicate through a 1-wire bus configuration. The master element can determine the presence and location of each of the one or more slave elements using an auto-discovery process. The master element can issue commands to the one or more slave elements to obtain moisture readings and/or temperature readings.