Center Pivot Irrigation Speed Control for Wind Drift Compensation
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Solution Overview
Problem
Center pivot irrigation systems face inefficiencies due to dynamic wind drift and evaporative losses (WDEL) throughout the day, leading to uneven water distribution and crop stress, as existing systems do not adjust irrigation speeds in response to changing environmental conditions.
Innovation Solution
The method involves adjusting the speed of the roving center pivot arm assembly based on real-time climatological data, using a microprocessor to modify the speed timer settings hourly, slowing down during the hottest and windiest times and speeding up during the coolest and calmest times to maintain consistent water application across a 24-hour cycle without disrupting the irrigation schedule.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the center pivot irrigation system operates at a constant speed throughout the day, then the system structure and control simplicity are maintained, but wind drift and evaporative losses cause non-uniform water distribution and reduced irrigation efficiency
Solution Approach 1:
The patent implements dynamic speed adjustment of the center pivot irrigation system by varying the on-time duration of the outermost electric-drive motor throughout the irrigation cycle. The speed timer is modified to provide different on-time durations at different times of day, allowing the system to adapt to changing environmental conditions (wind speed, temperature, humidity) while maintaining uniform water distribution. This transforms the previously static speed control into a dynamic system that responds to temporal variations in WDEL conditions.
2Productivity
If the irrigation system speed is varied to compensate for changing environmental conditions, then irrigation efficiency and water uniformity are improved, but the irrigation cycle duration and scheduling may be disrupted
Solution Approach 1:
The patent changes the temporal parameters of the irrigation system by modifying the on-time duration of the speed timer at different hours of the irrigation cycle. Specifically, the on-time duration is extended during nighttime hours (lower WDEL conditions) and reduced during daytime hours (higher WDEL conditions). This parameter adjustment allows the system to apply water more efficiently during favorable conditions while compensating for losses during unfavorable conditions, thereby maintaining overall irrigation efficiency without significantly altering the total cycle duration.
3Reliability
If the outermost motor is powered on for longer durations to compensate for high WDEL conditions, then water application uniformity is improved, but energy consumption increases
Solution Approach 1:
The patent optimizes energy consumption by dynamically adjusting the motor on-time duration parameter based on the temporal pattern of WDEL conditions. During nighttime hours when WDEL is naturally lower, the on-time duration is extended to maximize water application uniformity. During daytime hours when WDEL is higher, the on-time duration is reduced to minimize energy consumption while still achieving adequate water distribution. This time-varying parameter adjustment balances the trade-off between water application uniformity and energy consumption.
Data Source
AI summary
A method for controlling operation of a self-propelled irrigation system compensates for differences in expected wind drift and evaporative losses for time periods over the course of an irrigation cycle. Speed modifier values are determined for selected time periods to modify the base speed for the pivot arm assembly based on the corresponding expected wind drift and evaporative losses, with offsetting speed modifier values to modify the speed of the pivot arm assembly for other time periods, so that the period of time for completing an irrigation cycle remains unchanged. The pivot arm assembly is then controlled to move at the corresponding modified speed for each time period.