Water Sensor Feedback Control System for Surface Irrigation

Abstract

A water sensor feedback control system was developed to control semiautomatic irrigation of basins and borders. When water reaches a sensor at a downfield irrigation cutoff point, a signal to terminate irrigation is sent via wire or infrared (IR) telemetry to a station controller or receiver at the upper end of the field. The sensor uses a monostable interface to strengthen the signal for wire transmission, and prevents continuous IR transmission during the time the sensor is immersed or remains wet. The water sensor controller, powered by a 12-V battery, uses a silicon controlled rectifier (SCR) triggered by the feedback signal to discharge a capacitor through an electric solenoid. The energized solenoid actuates a gate release or valve to terminate irrigation of one field segment and begin irrigation of another. The water sensor system was tested in a level basin irrigation system.

Semiautomation of Irrigated Basins and Borders: II. Dual-function Turnout Gates

“…Different stages of crop growth also have different retarding effects on the rate of advance, which makes predicting the time required to complete irrigation difficult. Feedback can be provided by using water advance sensors (Humpherys and Fisher, 1995).…”

“…The actuator control unit, mounted on the gate frame, includes a 3PDT relay to control the gate with a water sensor or timer and a DPDT toggle switch for manual operation. The two irrigated basins immediately upstream from the check gate have drop-closed gates at the turnouts controlled by water sensors (Humpherys and Fisher, 1995). When water in the second basin reached the sensor, a control signal was transmitted by buried wire to the actuator control unit where it activated the control relay to open the check gate.…”

Managing Spatial and Temporal Variability in Irrigated Agriculture Through Adaptive Control

“…In these cases the response being sensed is the water advance down the field, where the sensing may be by contact means (Humpherys & Fisher, 1995) or non-contact (Lam et al, 2006). The outputs are depth of water applied (rather than crop yield) and the usual performance measures of efficiency and uniformity, and the objective is a traditional uniform application over the entire field.…”

Semiautomation of Irrigated Basins and Borders: III. Control Elements and System Operation

“…A water sensor control system was tested to provide feedback control for semiautomatic irrigation of basins and borders (Humpherys and Fisher, 1995). The sensor, placed about three-fourths of the basin length downfield, provided a signal via wire to a station controller to stop irrigation.…”