Center Pivot Irrigation Variable Rate Control
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Solution Overview
Problem
Center pivot irrigation systems face challenges in handling varying input water flow rates and selectively irrigating irregularly shaped areas within a field, leading to inefficiencies and waste of water, as they typically require uniform flow rates and cannot easily exclude non-irrigable areas.
Innovation Solution
A center pivot irrigation system with a controller that uses pulse control valves and adjusts rotation speed to deliver variable irrigation depths and exclude specific zones, allowing for targeted water application based on farmer-defined zones and soil conditions, without the need for variable speed pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a center pivot irrigation system uses uniform flow rates across the sprinkler arm, then uniform water application is achieved, but the system cannot handle varying input water flow rates and cannot selectively irrigate specific zones
Solution Approach 1:
The sprinkler arm is divided into multiple independently controllable segments or sections, each with its own flow control mechanism. This allows different zones to receive different water applications selectively while maintaining uniform flow within each zone, resolving the contradiction between adaptability and complexity by enabling zone-specific control without requiring complete system redesign
Solution Approach 2:
The system incorporates dynamic flow control capabilities that allow the sprinkler arm to adjust water flow rates in real-time based on input water availability and zone requirements. This dynamic adjustment enables the system to handle varying input flow rates while maintaining operational flexibility, balancing adaptability with manageable system complexity
2Productivity
If the sprinkler arm moves at higher speeds at outer spans, then coverage area increases, but uniform water application becomes difficult to maintain
Solution Approach 1:
The system uses variable speed control mechanisms that allow the sprinkler arm to dynamically adjust its rotation speed based on the spatial position and water flow requirements of different zones. This enables the arm to move faster in areas requiring less water and slower in areas requiring more water, maintaining uniform application while preserving overall productivity
Solution Approach 2:
The system changes operational parameters such as rotation speed and flow rate in response to varying conditions along the sprinkler arm span. By continuously adjusting these parameters, the system maintains uniform water application despite differences in linear speed at inner versus outer spans, resolving the contradiction between productivity and precision
3Adaptability or versatility
If all areas of the field are irrigated uniformly, then complete coverage is achieved, but water is wasted on non-irrigable areas such as rocky areas or roads
Solution Approach 1:
The irrigation system implements local quality control by allowing different zones to receive different water applications based on their specific needs. Non-irrigable areas such as rocky areas or roads can be excluded from irrigation while other zones receive appropriate water levels, eliminating water waste while maintaining adaptability for selective zone irrigation
Solution Approach 2:
The field is divided into multiple selectable zones that can be independently controlled. This segmentation allows the system to target irrigation only to areas that require it, preventing water waste on non-irrigable areas while maintaining the flexibility to adapt irrigation patterns to specific field conditions
Data Source
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AI summary
A center pivot irrigation system (100) is described that includes a controller (150) that makes use of a particular flow rate of input water to deliver differing or variable depths of irrigation to two or more user-defined areas under a pivot irrigator (110). The controller (150) operates to pulse control valves (120, 124) for the nozzles/sprinkler heads (121, 125) on and off as the sprinkler arm (110) rotates. The valve pattern (180) along the span of the sprinkler arm (110) is chosen during each operating cycle such that the total water flow through all the open valves matches the flow rate of the input or supply water to the pivot irrigator (110). To ensure the variable application depth, the speed may be changed during valve duty cycles. A farmer may define an irrigation plan (120) that defines the variable rate irrigation (VRI) zones and also defines exclusion or no spray zones in which no irrigation should occur.