Sprayer Valve Duty Cycle Correction Using Pressure Feedback
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Solution Overview
Problem
Existing agricultural sprayer systems face inaccuracies in applying agricultural products due to discrepancies between specified and actual duty cycles of valves, leading to misapplication and inefficiencies in crop treatment.
Innovation Solution
A system is introduced that includes a solenoid valve with a coil generating magnetic flux, a moveable valve operator, and a transient voltage suppression diode (TVS) to dissipate energy, allowing for precise control of the valve's duty cycle through a controller that corrects the actual duty cycle to match the specified cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the valve is operated by a controller with a specified duty cycle, then the valve control system can automate agricultural product application, but the actual duty cycle of the valve differs from the specified duty cycle due to mechanical response delays and tolerances
Solution Approach 1:
The system monitors the actual duty cycle of the valve by detecting when the valve operator transitions between open and closed positions, then compares this actual duty cycle to the specified duty cycle. Based on this comparison, the controller adjusts the modulation timing to compensate for mechanical response delays, ensuring the actual agricultural product application matches the intended specification.
Solution Approach 2:
The system performs preliminary calibration by determining the relationship between specified and actual duty cycles before normal operation. This preliminary characterization of valve response behavior allows the controller to pre-compensate for mechanical delays, adjusting the modulation signal timing in advance to achieve accurate duty cycle control.
2Ease of operation
If the specified duty cycle is used directly without correction, then the control system is simple to operate, but the agricultural product is misapplied to the crop resulting in too much or too little product
Solution Approach 1:
The system automatically determines and applies corrections to the duty cycle without requiring manual intervention. The controller self-adjusts the modulation timing based on monitored valve performance, eliminating the need for operators to manually calculate or compensate for mechanical response variations while maintaining precise agricultural product application.
Solution Approach 2:
The system continuously monitors actual valve duty cycle performance and feeds this information back to the controller, which automatically adjusts the modulation signal. This closed-loop feedback mechanism maintains accurate agricultural product application while keeping the operator interface simple, as the system self-corrects without requiring user intervention.
3Measurement precision
If the valve modulation timing is adjusted to compensate for mechanical response, then the actual duty cycle matches the specified duty cycle, but additional control complexity is introduced
Solution Approach 1:
The system adjusts timing parameters of the valve modulation signal to compensate for mechanical response delays. By changing the temporal parameters of the control signal rather than the physical valve components, the system achieves accurate duty cycle control through software-based parameter adjustment, minimizing additional hardware complexity.
Solution Approach 2:
Instead of mechanically adjusting valve components to achieve accurate duty cycles, the system substitutes mechanical adjustment with electronic timing control. The controller modifies the electrical modulation signal timing to compensate for mechanical response, replacing complex mechanical calibration mechanisms with simpler electronic parameter adjustment.
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
This system ensures accurate and precise application of agricultural products, minimizing waste and enhancing crop characteristics by aligning the actual duty cycle with the specified cycle, thereby improving application accuracy and efficiency.
Implementation Method 1
a solenoid valve with a coil generating magnetic flux
Implementation Method 2
a transient voltage suppression diode (TVS) to dissipate energy, allowing for precise control of the valve's duty cycle
Data Source
AI summary
A sprayer control system includes a plurality of smart nozzles each having at least one control valve with a valve operator, an electronic control unit for the valve operator, and one or more spray nozzles. The at least one control valve and the ECU control a flow rate of liquid agricultural product through the nozzles. A duty cycle modulator is in communication with the ECU and generates an applied duty cycle for the at least one control valve. The duty cycle modulator includes a specified duty cycle input having a specified duty cycle and a pressure monitor associated with the at least one control valve. A pressure comparator compares the valve pressure determined with the pressure monitor with a system pressure and generates a pressure error. An applied duty cycle generator generates the applied duty cycle based on the specified duty cycle modified by the pressure error.