Direct Injection Sprayer Sensing for Real-Time Concentration Control
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Solution Overview
Problem
Direct injection systems for agricultural sprayers face challenges in accurately measuring and controlling chemical application due to issues like lag-time, injection rate accuracy, and the need for constant dye concentration calibration, leading to inaccuracies in chemical concentration measurement.
Innovation Solution
A direct injection agricultural spray system with a primary sensor to determine chemical concentration upstream of the mixing point and a secondary sensor downstream of the nozzle, using optical sensors to establish a calibration curve for real-time control of chemical concentration, eliminating the need for initial calibration and allowing for accurate measurement regardless of dye concentration variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a primary sensor is used to establish maximum chemical concentration and calibration curve, then measurement precision is improved, but device complexity increases due to additional sensors and calibration requirements
Solution Approach 1:
The measurement system is divided into two functional segments: a primary sensor that establishes maximum chemical concentration and calibration curve, and a secondary sensor that measures actual chemical concentration in real-time. This segmentation allows each sensor to have a specialized function, improving overall measurement precision while distributing system complexity across modular components
Solution Approach 2:
The primary sensor performs preliminary calibration by establishing the maximum chemical concentration and calibration curve before the secondary sensor begins real-time measurements. This preliminary action creates a reference framework that enables the secondary sensor to accurately measure concentrations without requiring continuous recalibration, thereby improving measurement precision while limiting the ongoing complexity burden
2Measurement precision
If dye concentration is kept constant for sensor calibration, then measurement precision is improved, but ease of operation deteriorates due to strict calibration requirements
Solution Approach 1:
The primary sensor performs self-calibration by automatically establishing the maximum chemical concentration and calibration curve without requiring manual intervention or strict control of dye concentration. This self-service capability eliminates the operational burden of maintaining constant dye concentration while preserving measurement precision through automated reference establishment
Solution Approach 2:
The system allows dye concentration to vary while the primary sensor dynamically adjusts the calibration curve to accommodate these changes. This parameter change approach enables the system to maintain measurement precision even when dye concentration fluctuates, significantly improving ease of operation by removing the constraint of constant dye concentration
3Productivity
If ratio of full concentration to diluted concentration is used to estimate chemical application rate, then productivity is improved, but measurement precision deteriorates due to sensor errors
Solution Approach 1:
The secondary sensor provides real-time feedback on actual chemical concentration in the spray mixture, which is used to correct and refine the chemical application rate estimation. This feedback mechanism eliminates reliance on error-prone ratio calculations while maintaining high productivity through continuous, accurate measurements that enable immediate adjustments
Solution Approach 2:
The system replaces the mechanical calculation approach (ratio of full concentration to diluted concentration) with an optical sensing approach using the secondary sensor to directly measure chemical concentration. This substitution eliminates sensor errors inherent in ratio-based estimation while maintaining fast response times, thereby improving both measurement precision and productivity
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, real-time control of chemical application with reduced waste and quick adjustment of application rates, independent of initial dye concentration calibration, ensuring precise chemical delivery across varying concentrations and flow rates.
Implementation Method 1
A preferred method and system improve the application accuracy of direct injection (DI) systems via sensing that determines chemical concentration after an injection point and immediately before the mixed carrier and chemical enters the spray nozzle for delivery by that spray nozzle
Implementation Method 2
A primary sensor senses chemical concentration in a chemical injection line downstream of the chemical tank
Data Source
AI summary
A method for monitoring and controlling chemical concentration in a direct injection agricultural sprayer system monitors initial chemical concentration output from a chemical tank, carrier flow from a carrier tank, and mixed chemical concentration at nozzles of the spray system downstream of individual mixing points of the nozzles. Flow from the carrier tank and/or the chemical tank are controlled to target a set concentration at each of the nozzles. The initial chemical concentration establishes maximum concentration and a calibration curve for a chemical being applied and the mixed chemical concentration establishes an applied concentration in view of the calibration curve. A system is provided for the method.