Method And Apparatus For Optimizing Soil Moisture

• US 20070055407A1
• Filed: 10/31/2006
• Published: 03/08/2007
• Est. Priority Date: 02/11/2004
• Status: Active Grant

• Current Assignee: Allan Goldberg, James Zimmerman, Larry Hawkes, Larry Hopkins
• Original Assignee: Allan Goldberg, James Zimmerman, Larry Hawkes, Larry Hopkins
• Inventors: Zimmerman, James, Hopkins, Larry, Hawkes, Larry, Goldberg, Allan
• Granted Patent: US 7,574,284 B2
• Time in Patent Office: Days
• US Class Current: 700/284
• CPC Class Codes: A01G 25/167 Control by humidity of the soil itself or of devices simulating soil or of the atmosphere; Soil humidity sensors
• CPC Class Codes: B05B 12/12 responsive to conditions of ambient medium or target, e.g. humidity, temperature position or movement of the target relative to the spray apparatus B05B12/082, B05B12/084 take precedence
• CPC Class Codes: Y10T 137/1866 For controlling soil irrigation
• CPC Class Codes: Y10T 137/189 Soil moisture sensing

Abstract

A self-adjusting irrigation controller takes a pre-irrigation soil moisture reading prior to irrigation, chooses an amount of water to be dispensed corresponding to that reading from a table, and dispenses that amount of water. A predetermined length of time after the end of irrigation, the controller takes a post-irrigation soil moisture reading and compares the value of that reading to a predetermined target value. If the post-irrigation value differs substantially from the target value, the water amount corresponding to the pre-irrigation value in the table is adjusted to reduce that difference on the next scheduled irrigation cycle having that same pre-irrigation soil moisture reading. The target value is determined by watering the soil to field capacity, then computing the target value as a function of the reading of the sensor at field capacity. The controller thus converges toward an ideal runtime and follows changes in the environment. In the preferred embodiment, the soil moisture is indicated by sensor voltages, and the amount of water dispensed is governed by the runtime of the irrigation system.

Claims

1. A method of determining the field capacity of an irrigated soil, comprising the steps of:

a) repeatedly irrigating said soil for short periods of time at predetermined intervals;

b) measuring the moisture level of said soil at each of said intervals;

c) comparing successive measurements to each other; and

d) if said successive measurements indicate an increasing moisture level, determining said field capacity as being the moisture level at which successive measurements differ from each other by less than a predetermined threshold.

2. The method of claim 1, in which said periods of time are about three minutes, said predetermined intervals are about one hour, and said predetermined threshold is about 1% of full scale.

3. An irrigation system, comprising:

a) a plurality of zones to be irrigated, one of said zones being a master zone;

b) a moisture sensor positioned in said master zone and arranged to produce a signal representative of soil moisture in said master zone; and

c) a controller operatively connected to said moisture sensor and arranged to irrigate said master zone at selected times for a runtime determined by said signal; and

d) said controller being further arranged to irrigate the non-master zones of said system for a runtime equal to an individually selectable percentage of the master zone runtime.

4. In an irrigation controller in which soil moisture is read by at least one sensor at a predetermined time after the end of each irrigation cycle, and is compared to a predetermined target moisture level, a display showing for each sensor the identity of the sensor, the increase or decrease of soil moisture in successive readings, the current soil moisture level, and the target moisture level with respect to said current soil moisture level.

5. The display of claim 4, in which said readings are rolling averages of a plurality of individual measurements.

6. The display of claim 4, in which said soil moisture increase or decrease is indicated by scrolling indicia, said indicia scrolling in one direction to show moisture increase, and in the opposite direction to show moisture decrease.

7. The display of claim 4, in which said current soil moisture level is indicated by a bar indicium, said target moisture level being indicated by an indicium appropriately positioned along said bar.

8. The display of claim 4, in which said scrolling indicia alternate with a display of the next scheduled irrigation date.

9. In an irrigation controller associated with a sensor providing readings of data values indicative of the moisture content of a soil being irrigated, a display operable to show the currently sensed value and the rolling average of the values sensed during at least one predetermined immediately past period of time.

10. An irrigation controller programmable to establish a selectable regular watering schedule and a selectable new lawn schedule, said controller comprising means for automatically switching from said new lawn schedule to said regular schedule upon the expiration of a selectable grow-in period.

11. A soil moisture-sensing irrigation controller programmed to automatically vary dispensed water quantities in response to conditions sensed by calibrated sensors, said controller being programmed to perform an auto-calibration of said sensors prior to varying said dispensed water quantities.

12. The controller of claim 11 further programmed to allow power-up with a temporary manual or new-lawn schedule operation, said auto-calibration remaining in abeyance pending the completion of said operation and being then automatically performed.

13. The controller of claim 11 further programmed to selectively skip said auto-calibration on power-up if auto-calibration has previously been performed.

14. The controller of claim 11 further programmed to automatically recalibrate said sensor in response to predetermined operating conditions.

15. The controller of claim 14, which contains a lookup table of sensor readings corresponding to desired runtimes, and in which said predetermined operating conditions include sensor readings outside the range of readings encompassed by said table.

16. The controller of claim 14, in which a field capacity value is established for said sensor, and said predetermined operating conditions include a sensor reading indicating a soil moisture level greater than said field capacity.

17. The controller of claim 11, in which said sensors are automatically recalibrated at predetermined time intervals.

18. The controller of claim 11, in which said sensors are automatically recalibrated after a predetermined number of watering cycles.

19. The controller of claim 11, in which the calibration of said sensors is user-initiatable.