Field Sprayer Control Switching for Low-Flow Accuracy
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Solution Overview
Problem
Existing agricultural distribution machines face challenges in accurately controlling the flow rate of liquid distribution materials at low flow rates and in managing changes in spreading nozzle properties such as aging or wear.
Innovation Solution
The method involves operating the distribution machine with different control strategies, allowing the controlled variable to be switched or ignored based on the strategies. This includes adjusting the distribution material to a predefined system pressure in one strategy and to a predefined flow rate in another, using central metering and actuating elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If central volume flow control is used for large-area spreading, then large flow rates can be achieved, but flow rate detection and control become inaccurate at low flow rates
Solution Approach 1:
The patent segments the control function by providing separate control paths for high flow rates (central volume flow control) and low flow rates (decentralized control at individual nozzles). This allows each control mode to be optimized for its specific operating range, with the centralized controller switching between modes based on the required flow rate.
Solution Approach 2:
The control system dynamically switches between centralized and decentralized control modes depending on the operating conditions. The centralized controller activates decentralized control at individual nozzles when low flow rates are required, and uses central volume flow control when high flow rates are needed, making the system adaptable to varying operational requirements.
2Stress or pressure
If central pressure control is used to maintain system pressure, then pressure stability is improved, but complex information about each spreading nozzle must be known and monitored
Solution Approach 1:
The patent extracts the complex nozzle-specific information requirements from the centralized controller by implementing decentralized control at individual nozzles. Each nozzle has its own control element that operates independently based on local feedback, eliminating the need for the centralized controller to manage detailed information about each nozzle while maintaining pressure stability.
Solution Approach 2:
Each spreading nozzle is equipped with its own control element that autonomously regulates its operation based on local conditions and feedback. This self-service approach allows individual nozzles to maintain their own pressure and flow characteristics without requiring centralized management of detailed nozzle information, simplifying the overall control architecture.
3Measurement precision
If decentralized control at individual nozzles is implemented, then accurate control at low flow rates is achieved, but the system complexity increases
Solution Approach 1:
The patent merges centralized and decentralized control approaches into a unified hybrid system. The centralized controller provides overall system management and switches between control modes, while decentralized control elements at individual nozzles handle precise local regulation. This combination leverages the advantages of both approaches while distributing complexity across different levels of the control hierarchy.
4Adaptability or versatility
If control information is stored for each spreading nozzle, then individual nozzle control is enabled, but changes in nozzle properties due to aging or wear are ignored
Solution Approach 1:
The patent implements feedback mechanisms at each individual nozzle that continuously monitor actual flow and pressure conditions. This real-time feedback allows the decentralized control elements to detect and compensate for changes in nozzle properties due to aging or wear, ensuring reliable operation despite gradual degradation of nozzle components over time.
Data Source
AI summary
A method for an open-loop and/or closed-loop control of an agricultural distribution machine, in particular a field sprayer, when spreading liquid distribution material, in which at least one controlled variable, in particular a system pressure and/or a flow rate, is determined and/or predefined for the distribution material, on the basis of which the distribution material is conveyed at least in sections along a liquid circuit formed within the distribution machine, wherein the controlled variable, in particular the system pressure or the flow rate, is adjusted by way of at least one, in particular central, metering and/or actuating element arranged along the liquid circuit. In order to further improve spreading of liquid distribution material using an agricultural distribution machine, it is provided that the distribution machine can be operated with different control strategies, wherein the controlled variable which is adjusted by the at least one, in particular central, metering and/or actuating element, is switched or at least substantially ignored based on the control strategies.