Agricultural Sprayer Valve Control for Pressure Stability
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Solution Overview
Problem
Agricultural crop and field sprayers face challenges in maintaining constant boom pressure and droplet size due to varying speed, wind conditions, and sensor failures, which affect application rate and flow stability, and existing technologies like motorized regulation valves are slow to respond to changes in operating conditions.
Innovation Solution
The agricultural sprayer is equipped with multiple fail-safe modes that allow continued operation even when sensor signals are unavailable, using a controller to adjust the regulation valve position based on available signals, and incorporating feed forward control to adapt to changing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a motorized regulation valve is used to control flow and pressure, then the valve can handle large flow with relatively small pressure drop, but the response speed to changes in operating conditions is slow
Solution Approach 1:
The sprayer control system is divided into multiple independent sensor units distributed across different boom sections, each capable of detecting local spray conditions. This segmentation allows parallel processing of control decisions for different sections, improving overall response speed while maintaining the ability to handle large total flow rates through coordinated control of multiple valve actuators.
Solution Approach 2:
The controller pre-calculates optimal valve positions based on predicted operating conditions changes (such as upcoming headland turns or speed variations) and prepares control commands in advance. This preliminary action reduces the effective response time by having the system ready to act before actual conditions change, overcoming the inherent slowness of motorized valves.
2Reliability
If sensor redundancy is added to handle sensor failures, then the reliability improves, but the device complexity increases
Solution Approach 1:
Multiple sensor units are merged into a unified control architecture where the controller integrates data from all sensors and implements a single fail-safe control logic. This merging approach provides redundancy (improving reliability) while avoiding the complexity of multiple independent control systems, as the fail-safe mechanism is implemented through software logic rather than additional hardware complexity.
Solution Approach 2:
The sensor units are designed with multi-functionality, where each sensor can detect multiple parameters (pressure, flow rate, spray quality) and serve multiple control purposes. This universality means that a single sensor failure does not cripple the system, as other sensors can compensate, providing redundancy without requiring dedicated backup sensors for each function.
3Productivity
If the sprayer operates at varying speeds to adapt to field conditions, then the productivity increases, but the pressure stability and application rate consistency deteriorate
Solution Approach 1:
The control system dynamically adjusts the regulation valve position in real-time based on actual sprayer speed and desired application rate. Rather than maintaining a fixed valve position, the system continuously adapts the control parameters to match changing operating conditions, allowing the sprayer to operate at varying speeds while maintaining stable pressure and consistent application rates through active feedback control.
Solution Approach 2:
The controller continuously monitors actual pressure and flow rate from sensors and compares them against target values calculated for the current operating speed. This feedback mechanism automatically corrects deviations by adjusting the regulation valve, enabling the system to maintain pressure stability even when sprayer speed varies to adapt to field conditions such as headland turns or slope changes.
Data Source
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AI summary
An agricultural sprayer (1) with a pump (20), a boom (15) with a plurality of spray nozzles, a valve arrangement (28) associated with the boom, a feed conduit (25) for establishing fluid communication between an outlet of the pump (20), a return conduit (32) branching off from the feed conduit (25), a regulation valve (30), the regulation valve (30) applying a variable degree of throttling to the fluid flowing from the feed conduit (25) through the return conduit (32) and a controller (50) configured to be in receipt of a group of signals. The group of signals includes a signal from a pressure sensor (41) providing a signal representing the pressure of the fluid delivered to the valve arrangement (28), a flow sensor (42) providing a signal representing the flow rate of the flow to the valve arrangement (28), a regulation valve position sensor (31) sensing the position of the regulation valve (30), a pump speed sensor (27) sensing the speed of the pump (20) and a sprayer speed sensor sensing the speed of the agricultural crop and field sprayer (1). The controller (50) is configured to control the position of the regulation valve (30) in accordance with a plurality of operation modes, and the controller (50) is configured to automatically select an appropriate one of the operation modes, the plurality of operation modes including a full functionality mode and a plurality of fail-safe modes.