The hottest water-saving irrigation control system

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Water saving irrigation control system based on wireless sensor network

agricultural irrigation is a large water user in China, and its water consumption accounts for about 70% of the total water consumption. According to statistics, due to drought, the average affected area of grain in China is up to 20million hectares every year, and the consumed grain accounts for 50% to 50% of the national grain production reduction due to disasters. Since its durability, due to the backward technology and maintenance level, irrigation water consumption has been very serious, and the utilization rate of agricultural irrigation water is only 40% to 40%. It is assumed that based on the monitoring of soil moisture information, timely control of irrigation opportunities and water volume can effectively improve water use efficiency. However, measuring soil moisture manually and regularly not only consumes a lot of manpower, but also cannot be monitored in time; Using wired measurement and control system requires high wiring cost, which is not easy to expand, and brings inconvenience to farmland cultivation. Therefore, a water-saving irrigation control system based on wireless sensor network is designed. The system is mainly composed of low-power wireless sensor network nodes and ZigBee self-organizing mode, so as to prevent the defects of inconvenient wiring and poor sensitivity, complete the continuous monitoring of soil moisture, and realize the automatic control of agricultural water-saving irrigation, which not only improves the utilization rate of irrigation water, but also alleviates the contradiction of increasingly tense water resources in our country, It also provides a good growth environment for crop growth

1 system architecture

1.1 wireless sensor network

wireless sensor network technology is used in the water-saving irrigation control system, and its central technology is ZigBee self-organizing technology. ZigBee is a two-way wireless communication technology with low complexity, low power consumption, low data rate, low cost, high reliability and large network capacity. It is composed of use layer, network layer, medium connection control layer and physical layer. ZigBee network is divided into full function device (FFD) and reduce function device (RFD). ZigBee network supports three topologies: star, tree and shape. The system adopts mixing, and the bottom layer is multiple ZigBee monitoring networks, which are responsible for the collection of monitoring data. Each ZigBee monitoring network has a joint point and several soil temperature and humidity data acquisition nodes. The monitoring network adopts star structure, and the joint point is the base station of each monitoring network. Joint points have dual functions: one is to act as the coordinator of the network, and act as the automatic establishment and maintenance of the network and data aggregation; Second, as the interface between the monitoring network and the monitoring center, it transmits information with the monitoring center. This system has the function of automatic grouping. The wireless gateway is constantly in the monitoring mode, and the newly added wireless sensor nodes will be automatically detected by the network. At this time, the wireless routing will send the node information to the wireless gateway, and the wireless gateway will address and calculate its routing information, update the data transfer announcement and equip the association table

1.2 system architecture

the system takes the single chip microcomputer as the control center, and is composed of four parts: wireless sensor node (RFD), wireless routing node (FFD), wireless switch (FFD) and monitoring center. It is decided that ZigBee is self-organized, and GPRS is discussed between the monitoring center and wireless switch to transmit moisture and control information. Each sensor node determines the temperature and humidity sensor, automatically collects the moisture information, and analyzes it in combination with the preset upper and lower limits of humidity to determine whether irrigation is necessary and when to stop. Each node decides to supply power by solar cells, and the battery voltage is monitored at any time. Once the voltage is too low, the node will send an alarm signal of too low voltage. After sending it successfully, the node will enter sleep mode until the power is sufficient. The wireless switch connects ZigBee wireless network and GPRS network, which is the central part of the water-saving irrigation control system based on wireless sensor network, and serves as the maintenance of wireless sensor nodes. Sensor nodes and routing nodes independently form a multi hop network. The temperature and humidity sensors are scattered in the monitoring area and send the collected data to the nearest wireless routing node. The routing node selects the best route according to the routing algorithm and establishes the corresponding routing list, in which the list contains its own information and neighbor related information. It is decided that we have been reported to the remote monitoring center together with the Tier-1 supplier and Fraunhofer igcv1, so as to facilitate the remote monitoring and maintenance of users. The composition block diagram of the water-saving irrigation control system based on wireless sensor network designed in this paper is shown in Figure 1

2 hardware design

2.1 sensor node module

soil moisture is the primary limiting element of crop growth. The accurate collection of soil moisture information is the fundamental and guarantee for water-saving irrigation and optimal regulation of farmland. The effective implementation of water-saving technology plays a primary role. The hardware structure of sensor nodes in this system is shown in Figure 2

the system adopts tdr-3a soil temperature and humidity sensor, which integrates temperature and humidity measurement. It has the characteristics of sealing, waterproof and high precision. It is an ideal instrument for measuring soil temperature and humidity. The temperature range is -40 ~ +80 ℃, and the accuracy is ± 0.2 ℃; The humidity range is 0 ~ 100%, and the accuracy is ± 2% in the range of O ~ 50%. The output signal of the temperature and humidity sensor is a standard current loop of 4 ~ 20 mA. First, I/u conversion is carried out on the main controller circuit, and then a/D conversion is carried out into digital signals, and then the RF antenna is decided to transmit. The current converter adopts rcv420jp chip, which integrates resistance network, operation amplifier and standard 10 V reference voltage source, and can convert 4 ~ 20 mA current loop into 0 ~ 5 V voltage output

the signal conditioning circuit is shown in Figure 3. The A/D converter adopts the ADC converter inside the low-power RF integrated circuit CC2530. Its sampling frequency is 12 bits, and there is an 8-channel multiplexer inside. It can latch the decoded signal according to the address code, and only select one of the 8 analog input signals for a/D conversion

2.2 wireless communication module

the communication system of water-saving irrigation control system based on wireless sensor network is based on ZigBee wireless communication technology and GPRS. ZigBee is a highly reliable wireless data transmission network with three mission bands: 2.4 GHz (global), 915 MHz (United States) and 868 MHz (Europe). The system adopts the global general frequency band - 2.4 GHz, which is currently the preferred choice for the sensor network, and the transmission rate is 250 KB/s. This frequency band does not require a license in most non minority countries

problems that should be considered in wireless sensor node (RFD), non selective film tensile testing machine. The communication modules of line routing node (FFD) and wireless switch (FFD) all adopt CC2530 chip, which also has the necessary consistency in structure. Here, only the hardware structure of wireless switch is introduced in detail. Guan is responsible for the control and maintenance of the wireless sensor network and the fusion of information. He connects the sensor network and GPRS network, completes the conversion of the two communication protocols, discloses the position of the monitoring terminal, and transmits the collected data to the remote monitoring center. The structural frame is shown in Figure 4

Huawei GPRS communication module gtm900c and ti's ZigBee RF chip module CC2530 are adopted. Gtm900cgprs module supports GSM900/1800 dual band, provides power interface, analog audio interface, standardized SIM card interface and UART interface, and supports voice service, short message service, GPRS data service and circuit data service. CC2530 is a new generation of ZigBee SOC chip. It has up to 256 B flash memory, allows chip wireless download, supports system programming, and provides 101 DB link quality, excellent receiver sensitivity and robust anti-interference. In addition, CC2530 combines a fully integrated, high-power RF transceiver with an 8051 microprocessor, 8 KB ram, 32/64/128/256 KB flash memory, and a set of universal peripherals - including 2 USARTs, 12 bit ADC and 21 general purpose input output (GPIO). The PC software of the remote monitoring center uses Delphi to design the maintenance interface, establish the corresponding database, and complete the query, maintenance, printing and decision of soil moisture. GPRS network transmits control commands and soil temperature and humidity information

3 software design

in this water-saving irrigation control system, monitoring data and control commands are transmitted between wireless sensor nodes, wireless routing nodes, wireless switches and monitoring centers. The sensor node turns on the power supply, becomes original, establishes a link, and then enters the sleep mode. When the wireless switch receives the infix request, it triggers the infix. The experienced routing node activates the sensor node, sends or receives packets, and then continues to enter the sleep mode after the disposal, waiting for the request to activate again. In the same channel, only two nodes need to be able to communicate and decide the competition mechanism to obtain the channel. Each node sleeps and monitors the channel periodically. If the channel is idle, it will automatically seize the channel. If the channel is busy, it will back off for a period of time according to the backoff algorithm and then monitor the channel shape again. In the sequence design, the method of zero deviation and full-scale error less than 0.51 sb is mainly adopted to complete the acceptance and transmission of information

4 Conclusion

the water-saving irrigation control system based on wireless sensor network designed in this paper uses ZigBee wireless communication technology with low cost and low power consumption, which prevents the inconvenience of wiring and improves the sensitivity of the water-saving irrigation control system. The system adopts high-precision soil temperature and humidity sensor, and implements precision irrigation according to soil moisture and crop water use order. It can not only effectively deal with the problem of low water use rate of agricultural irrigation with a year-on-year increase of 25%, alleviate the contradiction of increasing tension of water resources, but also provide a better growth environment for crops, fully carry forward the role of existing water-saving equipment, optimize scheduling, improve efficiency, and make irrigation more superstitious and simple, Improve the maintenance level. This system also supports manual correction and remote control of relevant parameters, which is applicable to a variety of crops. It can increase the yield of crops, reduce the irrigation cost of agricultural products, and improve the irrigation quality. It has great implementation value. In addition, with different sensors, the system can form a monitoring network with different functions. (end)

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