A potting soil humidity closed-loop control system based on middle and lower layer soil humidity monitoring and pulse watering

Abstract

The application discloses a kind of based on middle and lower layer soil humidity monitoring and impulse watering's potted system, including controller, capacitive humidity probe, water pump and adjustable nozzle.Capacitive humidity probe is used to monitor middle and lower layer soil humidity, controller according to soil humidity value controls impulse watering program operation, the program is with T1 time water supply, T0 time stop cycle mode operation, T1 operation time 3-6 seconds, T0 time is 2-5 times of T1 time, give water and give sufficient time uniform infiltration.The system is through optimizing soil humidity monitoring position and watering mode, solve the uneven watering in the prior art, humidity control is not accurate, water resource waste and other defects, better control humidity range, for wet and dry plants and not tolerant plants provide good soil humidity environment.

Description

Technical Field

[0001] This invention relates to the field of potted plant watering technology, specifically a closed-loop control system for potted plant soil moisture based on monitoring the moisture content of the middle and lower soil layers and pulse watering. Background Technology

[0002] In potted plant care, the "water thoroughly when the soil is completely dry" method is often used. However, different plants have different water requirements. Neutral plants are neither drought-tolerant nor waterlogged-tolerant, while some plants like moisture but are afraid of waterlogging.

[0003] Existing technologies address the issue of uneven soil moisture by extending watering time, but they still have the following drawbacks:

[0004] 1. Unrepresentative Monitoring Results: In existing technologies, soil moisture monitoring points are typically located in the surface soil or elongated soil moisture sensors are used. These methods are significantly affected by the surface soil. As the soil gradually dries, the surface soil dries out first, and during watering, it becomes wet first, affecting the judgment of overall soil moisture. For example, when monitoring surface soil moisture, if the surface soil moisture is 70%, the sensor will judge the overall soil moisture to be 70%, while the moisture of the middle and lower layers of soil may still be less than 30%. The capacitance value of elongated soil moisture sensors is also affected by surface moisture. When the surface soil moisture reaches 100%, the average moisture value may already be 60%. If a soil moisture upper limit threshold is set at 60%, the watering process will end before the soil is fully hydrated.

[0005] 2. Inaccurate water control: Existing watering methods (such as continuous watering or equal-ratio intermittent watering) often result in water accumulating in the surface soil and then quickly flowing to the bottom of the pot. For example, in the equal-ratio intermittent watering mode, the ratio of watering time to interval time is 1:1, but due to soil structure and the effect of gravity, the water does not have enough time to infiltrate evenly, resulting in runoff, wasting water resources, and uneven humidity.

[0006] 3. Exacerbates uneven humidity: Once the topsoil dries out, it becomes more hydrophobic, preventing water from penetrating effectively and causing runoff. For example, in dry peat moss or garden soil, water may flow directly to the bottom of the pot, while the topsoil remains dry, further exacerbating uneven humidity and affecting plant growth. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to combine monitoring of the moisture content of the middle and lower soil layers with pulse watering to achieve uniform soil moisture and controllable moisture range, that is, to provide a closed-loop control system for potted soil moisture based on monitoring of the moisture content of the middle and lower soil layers and pulse watering.

[0008] This invention is achieved through the following technical solution: the system includes a soil capacitive moisture probe, a controller, a water pump, and an adjustable nozzle. This invention uses the capacitive method to monitor the moisture content of the middle and lower soil layers.

[0009] The capacitive humidity probe uses a PCB as a substrate, with electrodes of printed circuits on both sides serving as capacitors for the capacitive humidity probe. A blank area of ​​≥1 cm is left at the end of the PCB, and the capacitive humidity probe is treated with waterproof and anti-corrosion measures. When the capacitive humidity probe is fully inserted into the soil, the blank area contacts the surface soil, and the electric field distribution of the capacitor is restricted to avoid the surface soil due to the blank area design.

[0010] The capacitive humidity probe is connected to the humidity signal processing circuit integrated on the controller via a wire. The humidity signal processing circuit converts the capacitance value of the capacitive humidity probe into an electrical signal and transmits it to the processor.

[0011] The controller is used to set an upper and lower threshold for soil moisture, and to estimate the soil moisture value of the middle and lower layers based on the signal from the moisture processing circuit. When the soil moisture value is less than or equal to the lower threshold, the controller starts a pulse watering program, which operates in a cyclical mode of water supply time T1 and stop time T0; when the soil moisture value is greater than or equal to the upper threshold, the controller ends the pulse watering program.

[0012] The T1 water supply time ranges from 3 to 6 seconds, and the T0 stop time ranges from 2 to 5 times that of T1. For example, when T1 = 3 seconds, the T0 stop time ranges from 6 to 15 seconds to meet the water control needs of different plants, soil depths and soil substrates.

[0013] The water pump is connected to the adjustable nozzle via a conduit and is used to deliver water from the water source to the adjustable nozzle according to the controller's instructions. The adjustable nozzle has adjustable direction, angle, and dispersion area and is used to spray water evenly onto the surface of the potted soil.

[0014] This invention provides a closed-loop control system for potted plant soil moisture based on monitoring of the middle and lower soil layers and pulse watering, which has the following beneficial effects:

[0015] This potted plant watering system uses capacitance to monitor soil moisture. Capacitance provides more accurate moisture data than resistance methods and is less expensive than neutron detection, time-domain reflectometry, frequency-domain reflectometry, and tensiometer methods. The PCB-based capacitive humidity probe is easier to waterproof and corrosion-resistant, allowing for long-term contact with the lower soil layers and making the sampled moisture values ​​more representative.

[0016] Under closed-loop soil moisture control, the pulse watering program of this potted plant watering system stops the water flow after spraying the pot surface for time T1 and stops at time T0. The water then diffuses evenly from the soil surface to the middle and lower layers in a natural diffusion manner, which solves the hidden danger of uneven soil moisture and reduces the amount of wastewater flowing out from the bottom of the pot.

[0017] This closed-loop soil moisture control system for potted plants allows for better control of the humidity range due to representative sampling and uniform humidity diffusion. For example, the ideal upper limit of humidity when watering succulents is 50%. Existing technologies may result in uneven humidity if watering is stopped immediately upon detecting 50% humidity. If watering time is extended to avoid dry areas, the humidity may rise above 60%. This invention can stop watering immediately upon detecting 50% humidity in the middle and lower soil layers. Combined with the influence of higher surface humidity, the overall humidity is controlled within 55%, resulting in a more accurate humidity range. Attached Figure Description

[0018] Figure 1 The overall structural diagram of the present invention is shown, including a capacitive humidity probe 1, a controller 2, a water pump 3, and an adjustable nozzle 4;

[0019] Figure 2 This is a schematic diagram showing the separation of the capacitive humidity probe and the signal processing circuit of the present invention, including a humidity probe 1 with a capacitor 5 and a humidity signal processing circuit 7 integrated on the controller 2.

[0020] Figure 3 This is a flowchart of the watering control process of the present invention;

[0021] Figure 4 This is a schematic diagram showing the time relationship between pulse watering T0 and T1 according to the present invention;

[0022] Figure 5 This is a schematic diagram of the overall structure of a specific embodiment of the present invention;

[0023] Figure 6 This is a line graph comparing soil moisture content of the present invention and the equal-ratio intermittent watering method.

[0024] In the diagram: 1: Capacitive humidity probe, 2: Controller, 3: Water pump, 4: Adjustable nozzle, 5: Capacitor, 6: Display panel, 7: Signal processing circuit, 8: Water tank, 9: Base, 10: Flower pot. Detailed Implementation

[0025] The steps for the controller to operate the water pump to achieve water spraying are familiar to those skilled in the art and can be performed according to well-known conventions; therefore, detailed descriptions are omitted here. The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but should not be construed as limiting its scope.

[0026] like Figure 5 The diagram illustrates one overall implementation method of this system. A water tank 8 is installed inside the base 9. A controller 2 and a water pump 3 are located on the right side of the water tank. The controller is connected to the water pump 3 and a capacitive humidity probe 1 via wires. The water pump inlet is connected to the water tank 8 via a conduit, and the outlet is connected to two adjustable nozzles 4 via a T-junction and a conduit. A flowerpot 10 is placed on the surface of the base. By pinching the blank area of ​​the capacitive humidity probe 1, the probe is inserted into the potting soil. The end of the humidity sensor is then gently pushed until the blank area is flush with the surface soil. Since there are no electrodes in the blank area, the electric field only acts on the middle and lower soil layers in contact with the probe end. If the flowerpot is too shallow, the capacitive humidity probe can be tilted or even placed horizontally until its side contacts the bottom of the pot.

[0027] like Figure 2 As shown, the capacitive humidity probe uses a PCB as a substrate, with printed circuit electrodes on both sides as capacitors. There is an electrode-free area of ​​≥1 cm between the end of the capacitor and the end of the capacitive humidity probe, and an electrode-free area of ​​≥3 mm between the top of the capacitor and the top of the capacitive humidity probe. It is waterproof and corrosion-resistant, and is connected to the humidity signal processing circuit on the controller through wires.

[0028] Changes in the moisture content of the middle and lower soil layers cause changes in the capacitance value of the capacitor. The signal processing circuit includes a timer and a peak detection circuit. The oscillation frequency of the timer is determined by the capacitance value, and the peak detection circuit converts the oscillation signal into an electrical signal that can be recognized by the STM32F series chip.

[0029] The controller allows users to set upper and lower soil moisture thresholds via two BCD coded switches. Each coded value corresponds to a specific moisture level, with the 0th bit of the lower moisture limit switch disabling the automatic watering program. Users can select either the upper or lower moisture limit with a single click by rotating the coded switch.

[0030] like Figure 3 As shown, the controller estimates the humidity value through the electrical signal transmitted by the humidity signal processing circuit. When the set lower limit of soil humidity is less than or equal to the monitoring value of the middle and lower soil humidity, it does not change the current state. When the set lower limit of soil humidity is greater than or equal to the monitoring value of the middle and lower soil humidity, it starts the pulse watering program. When the set upper limit of soil humidity is less than or equal to the monitoring value of the middle and lower soil humidity, it ends the pulse watering program. If the soil humidity value does not increase after 90 seconds of watering, the watering program ends and an error is reported on the display panel 6.

[0031] The controller's pulse watering program is as follows: Figure 4As shown, the system cycles through a pattern of water supply time T1 followed by a stop time T0. For example, T1 = 3 seconds, T0 = 15 seconds. Water is supplied through an adjustable nozzle in a 3-second spray followed by a 15-second stop cycle. During the 3-second spray, water that the surface soil cannot absorb in time will gather and flow towards low-lying areas. After spraying stops, the water flow will cease, and during the 15-second stop, it will continue to diffuse evenly from the surface to the middle and lower layers naturally. The water pump continues to cycle through 3-second runs followed by 15-second stops until the soil moisture monitoring value in the middle and lower layers is greater than or equal to the upper limit set value of soil moisture. At this point, the controller terminates the pulse watering program.

[0032] Experiments show that when T1 = 3 seconds and T0 = 15 seconds, the garden soil absorbs water evenly; when T1 ≤ 5 seconds and T0 ≥ 15 seconds, the 1 to 3 mm Akadama soil absorbs water evenly; and when T1 ≤ 6 seconds and T0 ≥ 12 seconds, the 6 to 9 mm Akadama soil absorbs water evenly.

[0033] The application effects of the watering method of this invention and the proportional intermittent watering method were compared through experiments. The experimental subject was 1 to 3 mm thick Akadama soil at a depth of 10 cm, with a humidity control range of 30% to 60%. In this invention, T1 = 5 seconds and T0 = 15 seconds, while in the proportional intermittent watering method, T1 and T0 were both 5 seconds. The effectiveness of the two watering methods was verified by weighing. Figure 6 As shown, solid line A represents the soil moisture curve for irrigation according to this invention, and dashed line B represents the soil moisture curve for intermittent irrigation with equal proportions. The moisture stability of solid line A is better than that of dashed line B. Experiments have shown that by combining monitoring of soil moisture in the middle and lower layers with pulse irrigation, the soil moisture range becomes more stable.

Claims

1. A closed-loop control system for potted plant soil moisture based on monitoring of middle and lower soil moisture and pulse watering, characterized in that, include: Capacitive humidity probe 1 is used to sense the moisture content of the lower soil layer in the flowerpot; Controller 2 is used to set upper and lower thresholds for soil moisture and estimate the moisture value based on the capacitance value of the capacitive moisture probe. When the moisture value is less than or equal to the lower threshold, the controller starts a pulse watering program, which cycles through water supply time T1 of 3 to 6 seconds and stop time T0 (2 to 5 times T1). When the moisture value is greater than or equal to the upper threshold, the controller ends the watering program. The controller dynamically adjusts the pulse watering program based on the real-time moisture value to form a closed-loop control of soil moisture. Water pump 3 is used to deliver water to adjustable nozzle 4 according to the instructions of the controller; The adjustable nozzle 4 has an adjustable direction and angle, and is used to evenly spray water onto the soil surface.

2. The system according to claim 1, characterized in that, The capacitive humidity probe uses a PCB as a substrate, with printed circuit electrodes on both sides serving as capacitors 5 for the capacitive humidity probe. The PCB end has an electrode-free blank area of ​​≥1 cm, which is used to limit the distribution of capacitors to the middle and lower soil layers.

3. The system according to claim 1, characterized in that, The capacitive humidity probe is connected to the humidity signal processing circuit 7 of the controller via a wire. The humidity signal processing circuit converts the capacitance value into an electrical signal and transmits it to the processor.

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