Agricultural greenhouse monitoring and intelligent control scheme based on ZigBee technology
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I. Overview
The “Internet of Things” is known as the third wave of the world’s information industry after computers and the Internet. Industry experts believe that on the one hand, the Internet of Things can improve economic efficiency and greatly save costs; on the other hand, it can provide technical impetus for the recovery of the global economy. At present, the United States, the European Union, and China are all investing heavily in research and exploration of the Internet of Things. my country is also attaching great importance to the research of the Internet of Things. The Ministry of Industry and Information Technology, in conjunction with relevant departments, is conducting research on the new generation of information technology to form policies and measures to support the development of the new generation of information technology.
Intelligent control is to achieve the purpose of energy saving, comfort and convenience. It requires the formulation of detailed strategies and programs for intelligent control and monitoring of municipalities, households, agriculture, etc. However, the traditional intelligent control system is difficult to meet the requirements due to the restriction of many factors. In order to solve these problems, the industry has tried many methods, but they are basically closed-end, mostly using private protocols, which are difficult to communicate with each other, resulting in opaque structure, poor flexibility, and poor scalability. From a long-term perspective, the development trend of intelligent control systems is toward opening up, especially the integration of intelligent control and the Internet is one of the important development trends.
Intelligent agricultural control collects the temperature and humidity signals in the agricultural greenhouse in real time, as well as environmental parameters such as light, soil temperature, and soil moisture, and automatically turns on or turns off designated equipment. It can be processed at any time according to user needs, providing a scientific basis for automatic monitoring of agricultural ecological information, automatic control of facilities, and intelligent management.
The greenhouse monitoring and intelligent control solution uses wireless sensors such as light, temperature and humidity to collect the temperature, humidity signals and environmental parameters such as light, soil temperature, soil water content, CO concentration and other environmental parameters in the crop greenhouse in real time, and automatically turn it on or off. Designated equipment (such as remote control of irrigation, opening and closing of roller shutters, etc.).
Two project requirements
Two air temperature and humidity sensors are deployed in each smart agricultural greenhouse to monitor the air temperature and air humidity parameters in the greenhouse; two soil temperature sensors, two soil moisture sensors, and two illuminance sensors are deployed in each agricultural greenhouse. Used to monitor the soil temperature, soil moisture, light intensity and other parameters in the greenhouse. All sensors use DC 24V power supply, and only need to provide AC 220V city power in the greenhouse.
Each agricultural greenhouse deploys a set of collection and transmission equipment (including central node, wireless 3G router, wireless 3G network card, etc.) to transmit sensor data and equipment control instruction data of each agricultural greenhouse in the park to interact with the platform server on the internet.
Install 1 set of intelligent control equipment (including integrated controller, extended control distribution box, solenoid valve, power conversion adapter equipment, etc.) in each greenhouse that requires intelligent control functions to transmit control instructions and respond to control execution equipment . Realize the realization of electric roller blinds, smart water spraying, smart ventilation and other behaviors in the greenhouse.
Three system architecture design
(1) Overall structure
The overall architecture of the system is divided into four parts: sensor information collection, video monitoring, intelligent analysis and remote control.
(2) The system includes two parts:
■ Zigbee central node;
■ Edge gateway; (such as Ethernet, GPRS module, the combination of the two can realize long-distance data transmission.)
(3) Sensor information collection:
The data collection system is mainly responsible for the collection and control of data such as light, temperature, humidity, soil moisture content and video in the greenhouse. The upload of the data sensor adopts two modes: ZigBee and Rs485.
In the Zigbee transmission mode, sensor data is transmitted to the Zigbee central node through the Zigbee transmission module, and the control commands transmitted between the user terminal and the integrated controller are also transmitted to the central node through the Zigbee transmission module, eliminating the need for the deployment of communication cables Work. The central node then sends sensor data and control instructions to the business platform of the upper computer through the edge gateway. Users can access the upper computer system business platform through the wired network/wireless network, monitor the sensor parameters of the greenhouse in real time, and control the related equipment in the greenhouse. Zigbee mode has the advantages of flexible deployment and convenient expansion.
Four on-site layout of greenhouses
The greenhouse site is mainly responsible for the collection of the internal environmental parameters of the greenhouse and the execution of the control equipment. The collected data mainly includes the light, air temperature, air humidity, soil temperature, soil moisture and other values required for agricultural production.
There are two types of sensor data upload: Zigbee mode and RS485 mode. In RS485 mode, the data signal is transmitted by wire, which involves a lot of communication wiring. In the Zigbee transmission mode, sensor data is transmitted to the Zigbee central node through the Zigbee transmission module, and the control commands transmitted between the user terminal and the integrated controller are also transmitted to the central node through the Zigbee transmission module, eliminating the need for the deployment of communication cables. . The central node then encapsulates the sensor data and control instructions through the edge gateway and sends it to the system service platform located on the internet. Users can access the system business platform through the wired network/wireless network, monitor the sensor parameters of the greenhouse in real time, and control the related equipment in the greenhouse. Zigbee mode has the advantages of flexible deployment and convenient expansion.
The control system is mainly composed of an integrated controller, execution equipment and related lines. Through the integrated controller, various agricultural production execution equipment can be freely controlled, including water spray systems and air conditioning systems. The water spray system can support spray and drip irrigation. And other equipment, the air conditioning system can support roller blinds, fans and other equipment.
The collection and transmission part mainly transmits the values collected by the equipment to the server. The existing greenhouse equipment supports 3G, wired and other data transmission methods, and supports the IPv4 live network protocol and the next-generation Internet IPv6 protocol in the transmission protocol.
The business platform is responsible for providing users with all the functions of the smart greenhouse. The main functions include environmental data monitoring, data space/time distribution, historical data, over-threshold alarms and remote control. Users can also add video equipment as needed to realize remote video monitoring. Data space/time distribution displays the values collected by the system in an intuitive form to users of time distribution status (line graph) and spatial distribution status (field graph), historical data can provide users with a historical period of time value display; exceeding threshold alarm The user is allowed to formulate a custom data range, and reflect the out-of-range situation to the user.
Five data acquisition equipment
The project involves a sensor network module and a collection and transmission module. The main equipment included in each module is as follows:
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