Precipitation sensing to vary irrigation schedules
The present disclosure relates to methods and systems for varying irrigation schedules for a watering system (e.g., sprinkler system) based on detected precipitation. In one example, a system includes a rain sensor for detecting rain in a location where the rain sensor outputs a continuous rain signal when saturated with a threshold level of rain. The system also includes a sprinkler controller communicatively coupled to the rain sensor. The sprinkler controller opens one or more sprinkler valves based on a watering schedule. When the threshold level of rain is received, the sprinkler controller receives the rain signal during a saturation window of the rain sensor and varies the watering schedule based on rain detected by the rain sensor, where the variation to the watering schedule occurs outside of the saturation window of the rain sensor.
1. A method for adjusting an irrigation schedule for an irrigation system comprising:
receiving by a sprinkler controller a precipitation signal corresponding to received precipitation from a precipitation sensor, wherein the precipitation signal comprises an ON signal output by a precipitation sensor at a first time, the ON signal indicating that the precipitation sensor has absorbed a predetermined volume of water, and a termination of the ON signal output by the precipitation sensor at a second time, the termination indicating sufficient water has evaporated from the precipitation sensor to drop below the predetermined volume of water;
transmitting by the sprinkler controller the precipitation signal to a central controller, wherein the central controller is configured to:
determine a saturation window between the first time and the second time, the saturation window corresponding to a time for the sufficient water evaporation to occur,
determine an evapotranspiration rate at the precipitation sensor,
estimate a value of actual precipitation received at the precipitation sensor based on the saturation window and the evapotranspiration rate, and
adjust an irrigation schedule accounting for the estimated value of actual precipitation;
receiving by the sprinkler controller the adjusted irrigation schedule; and
activating by the sprinkler controller one or more sprinkler valves based on the adjusted irrigation schedule.
2. The method of claim 1 , wherein termination of the ON signal indicates that the precipitation sensor has dried, and the method further comprises time stamping by the sprinkler controller the drying event.
3. The method of claim 1 , wherein the adjusted irrigation schedule comprises instructions to skip or shorten at least one scheduled watering event for an irrigation area, wherein the at least one scheduled watering event occurs outside the saturation window.
4. The method of claim 1 , wherein estimating the value of actual precipitation received at the precipitation sensor is further based on temperature or humidity, such that adjusting the irrigation schedule accounts for temperature or humidity.
5. The method of claim 1 , wherein to adjust the irrigation schedule, the central controller is further configured to compare the estimated value of actual precipitation received to watering needs of vegetation watered by the one or more sprinkler valves to determine variations to watering times and/or frequency.
6. The method of claim 1 , wherein the precipitation sensor comprises a hygroscopic disk, and the hygroscopic disk
expands as water is absorbed, the expansion actuating a lever from an off position to an on position, and
shrinks as water evaporates, the shrinking deactivating the lever from the on position to the off position.
7. The method of claim 1 , wherein the central controller is further configured to estimate precipitation received by an area irrigated by the one or more sprinkler valves, wherein the estimation is based on the irrigation schedule, the saturation window, and meteorological data.
8. The method of claim 1 , wherein the central controller is further configured to estimate a soil moisture level based on the saturation window, and further adjust the irrigation schedule to account for the estimated soil moisture level.
9. The method of claim 1 , wherein the ON signal is a persistent signal that remains on for the duration of the saturation window.
10. The method of claim 1 , wherein the central controller is further configured to estimate the value of actual precipitation received at the precipitation sensor based on one or more precipitation sensor characteristics.