Method and apparatus for optimizing soil moisture

• US 7,133,749 B2
• Filed: 02/10/2005
• Issued: 11/07/2006
• Est. Priority Date: 02/11/2004
• Status: Active Grant

• Current Assignee: Toro Company (Toro)
• Original Assignee: Toro Company (Toro)
• Inventors: Zimmerman, James, Hopkins, Larry Kent, Hawkes, Larry, Goldberg, Allan Morris
• Primary Examiner(s): Picard, Leo
• Assistant Examiner(s): Masinick, Michael D.
• Application Number:
  US11/056,846
• Publication Number:
  US 20050194461A1
• Time in Patent Office: 635 Days
• Field of Search: 700/282, 700/284, 137/78.2, 137/78.3, 239/63
• 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