Method and apparatus using soil conductivity thresholds to control irrigating plants

• US 20070173981A1
• Filed: 01/20/2006
• Published: 07/26/2007
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: Nikola Vidovich
• Original Assignee: Nikola Vidovich
• Inventors: Vidovich, Nikola
• Granted Patent: US 7,546,181 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

Abstract

Method and apparatus determining the water absorption gradient and controlling the irrigation system based upon the water absorption gradient. The means for determining uses at least a first electrical coupling and a second electrical coupling, which electrically couple with a first probe and a second probe, placed in the soil near the at least one plant.

Claims

1. A method of operating an irrigation system delivering water to at least one plant, comprising the steps of:

determining a water absorption gradient based upon a present value and a past value;

wherein both said present value and said past value, are measured functions of soil conductance between at least two probes located in soil near said plant; and

controlling said irrigation system based upon said water absorption gradient.

2. The method of claim 1, where said plant includes at least one of a grass, a clover, an alfalfa, and a ground cover.

3. The method of claim 1, wherein said irrigation system delivers said water to at least two of said plants.

4. The method of claim 3, wherein said irrigation system delivers said water to a lawn including said at least two plants.

5. The method of claim 1, wherein the step determining said water absorption gradient, comprises the steps:

determining said water absorption gradient between two of said probes located in said soil near said plant.

6. The method of claim 1, wherein the step determining said water absorption gradient, comprises the steps:

establishing a present value of the electrical conductivity between said probes; and

calculating said water absorption gradient based upon said present value and said past value.

7. The method of claim 6, wherein the step calculating said water absorption gradient, further comprises the step:

creating said water absorption gradient based upon the difference of said present value and said past value.

8. The method of claim 6, wherein the step determining said water absorption gradient further comprises the step:

setting said past value to said present value.

9. The method of claim 7, wherein the step setting said past value, comprises the step:

writing said present value to a non-volatile memory to create a stored value of said past value.

10. The method of claim 9, wherein the step creating said conductivity difference, comprises the step:

reading said stored value from said non-volatile memory to retrieve said past value.

11. The method of claim 1, wherein the step controlling said irrigation system, comprises at least one of the step:

controlling at least one electric valve directing said water to said at least one plant based upon said water absorption gradient.

12. The method of claim 11, wherein the step controlling said electric valve, comprises at least one of the steps of the group consisting of:

turning-off said electric valve when said water absorption gradient is below a first threshold; and

turning-on said electric valve when said water absorption gradient is below a second threshold.

13. The method of claim 12, wherein the step turning-off said electric valve, further comprises one of the steps:

turning-off said electric valve when said difference is less than or equal to said first threshold multiplied by said present value; and

turning-off said electric valve when said difference is less than said first threshold multiplied by said present value.

14. The method of claim 12, wherein the step determining said water absorption gradient further comprises the step:

creating a soil conductivity scale ratio from said difference divided by said present value; and

wherein the step turning-off said electric valve, further comprises one of the steps;

turning-off said electric valve when said soil conductivity scale ratio is less than or equal to said first threshold; and

turning-off said electric valve when said soil conductivity scale ratio is less than said first threshold.

15. The method of claim 12, wherein said first threshold is less than or equal to one-eighth.

16. The method of claim 12, wherein the step turning-on said electric valve, further comprises one of the steps:

turning-on said electric valve when said difference is less than or equal to said negative of said second threshold multiplied by said present value; and

turning-on said electric valve when said difference is less than said negative of said second threshold multiplied by said present value.

17. The method of claim 12, further comprising the step:

creating a soil conductivity scale ratio as said difference divided by said present value; and

wherein the step turning-on said electric valve, further comprises one of the steps;

turning-on said electric valve when said soil conductivity scale ratio is less than or equal to said negative of said second threshold; and

turning-on said electric valve when said soil conductivity scale ratio is less than said negative of said second threshold.

18. The method of claim 12, wherein said second threshold is at most negative one-half.

19. The method of claim 18, wherein said second threshold is at most negative five-eighths.

20. An apparatus implementing the method of claim 1, comprising:

a first electrical coupling and a second electrical coupling to

means for determining said water absorption gradient between said at least two probes coupled to said first and said second of said electrical couplings; and

means for controlling said irrigation system based upon said water absorption gradient driving a control electrical coupling with an irrigation control signal.

21. The apparatus of claim 20, wherein at least one of said probes has a face with a surface area of at least N square inches.

22. The apparatus of claim 21, wherein each of said probes has said face with said surface area of at least said N square inches.

23. The apparatus of claim 21, wherein said N is at least one and one-half.

24. The apparatus of claim 21, wherein for each of said probes, said probe includes at least one member of the group consisting of:

said face is nearly flat;

said face is rounded;

said face is at least partly concave;

said face is at least partly convex;

said face has a polygonal boundary; and

said face has a curved boundary.

25. The apparatus of claim 20, wherein at least one member of a means group, comprises at least one instance of a member of the group consisting of:

a finite state machine;

a computer accessibly coupled to a memory and directed by a first program system including at least one program step residing in said memory to support determining said water absorption gradient between said probes;

an inferential engine;

wherein said means group, consists of;

said means for determining and said means for controlling.

26. The apparatus of claim 20, further comprising:

said means for determining communicatively coupling said means for controlling to provide said water absorption gradient to said means for controlling.

27. The apparatus of claim 20, further comprising:

a computer accessibly coupled to a memory and directed by a program system comprising program steps residing in said memory;

said computer electrically coupled with said means for determining and electrically coupled to said means for controlling;

wherein said program system, comprises the program steps;

determining said water absorption gradient between said probes located in soil near said plant; and

controlling said irrigation system based upon said water absorption gradient.

28. The apparatus of claim 26, wherein the means for determining, comprises:

an alternating current (AC) source electrically coupled to a first of said probes and to a second of said probes applying a test signal at a carrier frequency;

a demodulator electrically coupled to said first of said probes and said second of said probes to create an amplitude signal; and

an analog to digital converter electrically coupled to said amplitude detector receiving said amplitude signal to create said present value.

29. The apparatus of claim 28, wherein said carrier frequency is at least one hundred Herz (Hz).

30. The apparatus of claim 28, wherein said demodulator, comprises:

a band pass filter electrically coupled to said first of said probes and said second of said probes to create a filtered output signal resonant at said carrier frequency; and

an amplitude detector electrically coupled to said band pass filter receiving said filtered output signal to create an amplitude signal.

31. The apparatus of claim 30, wherein said amplitude detector, comprises at least one of the group consisting of:

a peak detector, an root-mean-square detector, an integrator, and a windowed integrator.

32. The apparatus of claim 30, wherein said demodulator, further comprises:

said amplitude detector creating a first amplitude signal; and

an attenuator electrically coupled to said amplitude detector receiving said first amplitude signal to create said amplitude signal.