Yunseop Kim

Remote Sensing and Control of an Irrigation System Using a Distributed Wireless Sensor Network

Efficient water management is a major concern in many cropping systems in semiarid and arid areas. Distributed in-field sensor-based irrigation systemsoffer a potential solution to support site-specific irrigation management that allows producers to maximize their productivity while saving water. This paper describes details of the design and instrumentation of variable rate irrigation, a wireless sensor network, and software for real-time in-field sensing and control of a site-specific precision linear-move irrigation system. Field conditions were site-specifically monitored by six in-field sensor stations distributed across the field based on a soil property map, and periodically sampled and wirelessly transmitted to a base station. An irrigation machine was converted to be electronically controlled by a programming logic controller that updates georeferenced location of sprinklers from a differential Global Positioning System (GPS) and wirelessly communicates with a computer at the base station. Communication signals from the sensor network and irrigation controller to the base station were successfully interfaced using low-cost Bluetooth wireless radio communication. Graphic user interface-based software developed in this paper offered stable remote access to field conditions and real-time control and monitoring of the variable-rate irrigation controller.

Instrumentation and Control for Wireless Sensor Network for Automated Irrigation

An in-field sensor-based irrigation system is of benefit to producers in efficient water management. A distributed wireless sensor network eliminates difficulties to wire sensor stations across the field and reduces maintenance cost. Implementing wireless sensor-based irrigation system is challenging on seamless integration of sensing, control, and data communication. An automated sensor-based irrigation system was developed for an integrated wireless in-field sensor network and automated variable rate irrigation. Field conditions were real-time monitored sitespecifically by in-field sensor stations distributed across the field. Each sensor station measured soil moisture, soil temperature, and air temperature, while one weather station recorded precipitation, wind speed and direction, air temperature, relative humidity, and solar radiation. Sensors and a data logger were self-powered by a solar panel and sensory data was periodically sampled and wirelessly transmitted to a base station about 700 m away from the sensor stations. A host computer received and real-time displayed field data without interference. This paper describes details of the design and construction of wireless communication, hardware used, and the costs and benefits of the control system.

Software Design for Wireless In-field Sensor-based Irrigation Management

A wireless in-field sensor-based irrigation management system is of benefit to producers in efficient water management, but implementing sensor-based irrigation control and monitoring is challenging in sensor fusion and data interface. Wireless in-field sensing and control software was developed for user-friendly interface of an integrated wireless in-field sensor network and automated variable rate irrigation. In-field sensory data was periodically sampled and remotely transmitted to a computer. Variable rate irrigation was controlled by the computer that reads information about field condition and GPS positions of sprinklers and transmits control signals to an irrigation controller via real-time wireless communication. This paper describes details of the software design using graphic user interface for wireless control and monitoring of a variable rate irrigation system.

A Remote-Real-Time Continuous Move Irrigation Control and Monitoring System

Continuous move irrigation systems have been modified since the 1990s to support variable rate irrigation. Most of these systems used PLC (Programmable Logic Controllers) technology that did a good job of on-site control but were expensive to add remote, real-time monitoring and control aspects made possible by wireless sensor networks and the Internet. A new approach to control and monitoring continuous move irrigation systems is described. This system uses a Single Board Computer (SBC) using the Linux operating system to control solenoids connected to individual or groups of nozzles based on prescribed application maps. The main control box houses the SBC connected to a sensor network radio, a GPS unit, and an Ethernet radio creating a wireless connection to a remote server. A C-software control program resides on the SBC to control the on/off time for each nozzle group using a “time on” application map developed remotely. The SBC also interfaces with the sensor network radio to record sensors on the irrigation system monitoring performance and in the field monitoring irrigation soil and crop conditions. The SBC automatically populates a remote data base on a server in real time and provides software applications to monitor and control the irrigation system from the Internet.

Evaluation of Wireless Control for Variable Rate Irrigation

Development of a variable rate irrigation control system allows producers to maximize water efficiency, while minimizing the effects on their productivity. This research evaluated the performance of an irrigation system for variable rate water application with real-time wireless control and monitoring. A self-propelled linear sprinkler system with a program logic controller (PLC) was wirelessly interfaced with a base computer located 700 m away by using Bluetooth radio modules. GUI-based user-friendly software was developed to receive GPS locations of the irrigation cart and send control signals to sprinklers every second either automatically or manually. The base computer received geo-referenced positional information of the irrigation cart from a differential global positioning system (DGPS) and sent control signals to execute 30 solenoid valves via real-time wireless communication. Individual control for all 30 sprinkler nozzle banks was identified and the performance of the four selected banks was quantified with measurement of water collected by catch cans that were uniformly distributed on soil surface across the field. Catch can readings compared to irrigation amount showed about 200 ml difference of water between two irrigation patterns and no significant transition differences on both GPS-based automatic and GUI-based user’s irrigation controls at wind speed of 9-20 km/h. The benefit of the real-time wireless irrigation system will extend to a closed-loop control for automated irrigation system with in-field sensing feedback of plant and soil conditions.

Integrated Decision Support, Sensor Networks and Adaptive Control for Wireless Site-specific Sprinkler Irrigation

The development of site-specific sprinkler irrigation water management systems will be a major factor in future efforts to improve the various efficiencies of water-use and to support a sustainable irrigated environment. The challenge is to develop fully integrated management systems with supporting elements that accurately and inexpensively sense within-field variability and then optimally control variable-rate water application systems in ways that account for the spatial variability affecting water use. Recent advances in sensor and wireless radio frequency (RF) technologies have enabled the development of distributed in-field sensor-based irrigation systems to support site-specific irrigation management. Thus, integration of a decision making process with a distributed wireless sensor network (WSN) and providing real time input to site-specific controls is a viable option. This presentation reviews research on the implementation of an in-field micrometeorological information that was fed from the distributed WSN and displayed on a geo-referenced field map in a computer base station. Low-cost Bluetooth wireless RF communications from both a distributed WSN and the machine controls monitoring of sprinkler status and GPS location were interfaced with a computer base station for processing by a decision support program, which updated the instructions to the variable rate irrigation controller for real-time site-specific control. The decision support was optimized to adapt changes of crop design, irrigation pattern, and field location for instructions for individual sprinkler heads on how much water to apply and where. A graphical user interface (GUI) with a simple click-and-play menu was used, which also allowed growers to remotely access field conditions and irrigation status at the home or office via the wireless RF communications

Evaluation of Closed--loop Irrigation Control with Wireless Sensor Network

Automated site--specific sprinkler irrigation system can save water and maximize productivity, but implementing automated irrigation is challenging in system integration and decision making. A controllable irrigation system was integrated into a closed--loop control with a distributed wireless in--field sensor network for automated variable--rate irrigation. An experimental field was configured into five soil zones based on soil electrical conductivity. Micrometeorological sensors were installed on each zone of the distributed wireless sensor network and remotely monitored by a base station for decision making. Soil water sensors were calibrated with a neutron probe and individually identified for their response ranges at each zone. Irrigation decisions were site--specifically made based on feedback of soil water conditions from distributed in--field sensor stations. Variable--rate water application was remotely controlled by the base station to actuate solenoids to regulate the amount of time an individual group of sprinkler nozzles was irrigating in a 60--sec time period. The performance of the system was evaluated with the measurement of water usage and soil water status throughout the growing season.

Performance of a Continuous Move Irrigation Control and Monitoring System

Precision irrigation systems can have inherent errors that affect the accuracy of variable water application rate and affect the transferability of the control system. The objective of this paper was to assess the performance, and transferability of a remote irrigation monitoring and control system (RIMCS) designed for precision water management on continuous move irrigation systems. The RIMCS varies water application rate by pulsing nozzles controlled by solenoids connected via relays to a single board computer (SBC) with wireless Ethernet connection to a remote server. The system also monitors irrigation system flow, pressure, and position and accommodates wireless sensor networks installed in the field. The system was installed on a linear move (LM) irrigation system in the lower Yakima Valley of eastern Washington State and on a LM in the Nesson Valley of western North Dakota. For the Washington LM, four pre-defined irrigation patterns were imposed under each of two spans and variable rates were applied as a percentage of the nozzle base application rate. Each nozzle was pulsed to create the intended irrigation pattern across the span length and along the LM travel direction. Tests were conducted in the months of June, August and September 2005. For the North Dakota LM, a quadratic pattern was imposed pulsing banks of nozzles along the LM travel direction. Standard catch can tests were performed at the middle of the irrigation pattern blocks, at the blocks boundaries and for the typical LM sprinkler application pattern. The system performance was evaluated using catch can water depth error assessment when compared to set target values. Variable water application depths using the RIMCS created the target application patterns with application accuracies in the range of uniform application uniformity coefficients of 88 – 96%. The RIMCS was successfully transferred to another LM in North Dakota.