Design and implementation of intelligent automatic irrigation system

O Introduction

Water is the basis of life. The normal life activities of plants are based on the process of continuous water absorption, conduction and transportation, utilization and loss. However, water resources in my country are seriously insufficient, making my country one of the 13 countries with the poorest freshwater resources in the world. The per capita freshwater resources are only one-fourth of the world's per capita. The lack of water resources has brought great obstacles and difficulties to the development of agriculture in my country. The soil for the growth of crops needs to maintain a certain humidity. People usually irrigate crops based on their planting experience. They cannot control the amount of watering in time or accurately, which often causes flooding, and wastes a large part of water resources in vain. How to use limited water resources and take "water-saving agriculture" has become a growth point for agricultural production to obtain the best benefits and sustainable and stable development. Therefore, the intelligent irrigation system using tap water power generation, controlling sprinkler irrigation and micro-irrigation systems, can effectively reduce leakage and evaporation losses during field irrigation. The existing irrigation systems all require external power supply, which has certain safety hazards and is troublesome. This system can be used in areas without power supply conditions. Its biggest advantages are water saving, energy saving, and labor saving.

1. Design goals and implementation plan description

The existing automatic irrigation system needs an external power supply, which has certain safety hazards. In addition, the program of the existing automatic irrigation device is generally fixed in the system's program memory, which can only simply set the irrigation time and cycle time, and cannot be flexibly adjusted according to different seasons. This system connects a small DC generator to the fan blades in a sealed special box, uses water flow to drive the fan blades to rotate to generate electricity, and then stores the electricity in the battery to power the monitoring circuit and the solenoid valve. This device uses a hygrometer and a photoresistor to detect signals, and tap water is used to generate electricity to power an automatic irrigation device that does not require an external power supply. The monitoring circuit of the device consists of four parts: signal acquisition part, irrigation control part, power supply part, and execution part. As shown in Figure 1.

1.1 Signal acquisition part

1.1.1 Soil moisture detection

Silicon hygroresistor is used as the sensor to detect soil moisture. Its response time is less than 5 s at 25℃ and the detection range of soil moisture content is 0～100%.

When the humidity sensor is inserted into the soil, the resistance of the humidity sensor is different due to the different water content of the soil. The humidity is judged by the humidity resistor and IC1NE555. If the soil is dry, the humidity resistor has a larger resistance, NE555 flips, and outputs a high level (approximately the power supply voltage).

When adjusting, insert the hygroscopic resistor into water, adjust Rp1 so that the output of pin 3 of NE555 is 12 V, then take the hygroscopic resistor out of water and wipe it dry, adjust Rp1 so that the output is 0 V, and repeat this adjustment several times to meet the requirements.

1.1.2 Sunlight intensity detection

The photoresistor and NE555 are used to judge whether the light is strong. If the light is strong at noon, the 3rd pin of IC2 NE555 outputs a low level. At this time, no matter whether the soil is dry or not, watering is not done. NE555 is used here to judge. When the sunlight is weak in the evening, the resistance of the photoresistor is large, and NE555 flips and outputs a high level (power supply voltage).

1.2 Irrigation control

1.2.1 AND Gate Decision

When IC1 and IC2 output high level at the same time, IC3 CD4073 outputs high level. No matter which of IC1 and IC2 does not meet the conditions, IC3 outputs low level.

1.2.2 Delay circuit

The delay is achieved through the oscillation circuit composed of CD4060, capacitor, resistor and adjustable resistor. The time from CD4060 starting to work to entering the holding state is the irrigation time. The resistance value of Rp3 can be adjusted to change the delay time.

1.3 Power supply

Since tap water flows quickly in the water pipe, part of its kinetic energy can be recycled. The tap water pressure drives the wind blades to drive the micro generator, and the generator generates electricity that is stored in the lithium battery. The energy in the lithium battery is then transferred to a 6V or 12V battery through a boost circuit. This part of the electricity is used to provide power for the automatic irrigation monitoring circuit.

1.4 Execution

The voltage output by the humidity detection part is used to control the closure of the relay, and then to control the on and off of the solenoid valve to implement automatic irrigation.

A switch is added between the solenoid valve and the power supply so that it can be forced to open and close. When you want to enjoy the beautiful irrigation scenery, just force the solenoid valve to open.

2 Conclusion

The test proves that the device has the following advantages:

(1) Good system stability. The circuit is mainly composed of analog circuits, which do not require high precision, good stability, and adjustable monitoring range and delay time.

(2) High safety. This device generates electricity from tap water, and the output is low voltage, without any safety hazards.

(3) Low cost. The device does not require an external power supply, is noiseless, low cost, small in size, and has a wide range of applications, making it easy to promote and use.

(4) Environmental protection. Water power generation saves energy, is pollution-free, and protects the environment.

(5) It can cooperate with garden developers to save a lot of manpower and material resources for the planting industry. This energy-saving equipment will become a beneficiary of the planting industry.

(6) It can be used in remote mountain villages and places where electricity is not well developed to enable local cash crops to grow better.