Capacitive Sensor System for Forage Harvester Crop Measurement
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Solution Overview
Problem
Self-propelled forage harvesters face challenges in accurately measuring crop moisture, density, and throughput due to limitations in existing sensors, particularly high errors with conductivity sensors and high costs associated with near-infrared (NIR) sensors.
Innovation Solution
A capacitive sensor system with multiple electrodes arranged in the discharge spout forms capacitors, utilizing changes in capacitance to measure moisture content, density, and throughput, offering improved accuracy and reduced manufacturing costs compared to NIR sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conductivity sensor is used for moisture measurement, then the manufacturing cost is reduced, but the measurement precision deteriorates due to large errors and insufficient compensation of influencing variables
Solution Approach 1:
The patent replaces conductivity-based measurement with capacitance-based measurement. The capacitive sensor system measures moisture content through capacitance changes caused by the dielectric properties of the crop material, eliminating the need for complex conductivity compensation algorithms while achieving higher measurement accuracy.
Solution Approach 2:
The patent changes the measurement parameter from electrical conductivity to electrical capacitance. By measuring capacitance rather than conductivity, the system achieves better moisture measurement precision because capacitance is less affected by varying crop properties such as density and flow rate, while still using simple and inexpensive capacitive sensors.
2Measurement precision
If a near-infrared sensor is used for moisture measurement, then the measurement precision is improved, but the manufacturing cost increases significantly
Solution Approach 1:
The patent uses inexpensive capacitive sensors instead of expensive near-infrared sensors. The capacitive sensor system achieves comparable or superior measurement accuracy to NIR sensors while being significantly more cost-effective, making it suitable for widespread implementation in forage harvesters.
Solution Approach 2:
The patent substitutes optical measurement (near-infrared) with electrical measurement (capacitance). This substitution maintains high measurement precision while dramatically reducing manufacturing costs, as capacitive sensors are simpler to manufacture and do not require complex optical components.
3Device complexity
If the feed roller height is used to determine throughput, then the device complexity is reduced, but the measurement precision deteriorates due to unrecorded influencing variables such as material properties
Solution Approach 1:
The capacitive sensor system serves multiple measurement functions simultaneously. The same capacitive electrodes used for moisture measurement also provide density and throughput information through capacitance changes, eliminating the need for separate measurement systems and reducing overall device complexity while improving measurement accuracy.
Solution Approach 2:
The patent changes from mechanical measurement (feed roller height) to electrical measurement (capacitance). Capacitance measurements provide direct information about material properties including density, moisture, and throughput without requiring mechanical calibration, thereby improving measurement precision while maintaining simple device architecture.
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 capacitive sensor system provides accurate measurements of crop parameters, including moisture, density, and throughput, while being more economical than NIR sensors, enhancing the operational efficiency of self-propelled forage harvesters.
Implementation Method 1
The capacitance of the capacitors in the chute is influenced by shredded crops or chopped crops that have been chopped by chopper drums and/or a conditioning device
Implementation Method 2
Shredded material has a significantly higher permittivity than air. The higher permittivity of the chopped material can be due to a higher proportion of water compared to air. This property causes the capacitance of a capacitor to change when the shredded material is in the vicinity of the capacitor compared to air
Data Source
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AI summary
The present invention relates to a self-propelled forage harvester (1) and a method for controlling this forage harvester (1). The present invention is based on the general concept that a measuring device (4) has several spaced-apart electrodes (5) arranged in the discharge chute (3), wherein these electrodes (4) arranged in the discharge chute (3) form several capacitors (20). This makes it possible to determine conveying-specific and/or crop-specific parameters. For example, the moisture, density, or flow rate through the discharge chute of the forage harvester can be measured with the measuring arrangement. Based on the data obtained, it is possible to control a subsystem, e.g., the header (22).