关键词: 物联网系统, 模糊PID控制, NB-IoT, ZigBee, 智能控制

Abstract: In order to solve the issues of weak environmental data perception, large workload of field maintenance, limited wireless coverage area, low efficiency and high cost of production management, design and test of NB-IoT system for fruitvegetable agriculture based on fuzzy PID control was presented. STM32L475VET6 ultralow power chip was used as the main control chip. Wide area wireless network was established by NB-IoT and ZigBee dualprotocol fusion networking technology and the algorithm of ring buffer queue. Monitoring terminal equipment and remote cloud monitoring platform were designed. Environmental factor information collected by local terminal nodes was connected to the cloud server for statistics and analysis. The system automatically adjusted and controlled the feedback control equipment according to the collected data. By this, it aimed to achieve the purpose of widearea coverage monitoring and intelligent feedback regulation of environmental factors in low power consumption mode. It realized a complete set of IoT system design of fruit and vegetable greenhouses from perception layer, network layer to platform layer and application layer. Simulation test was carried out by applying fuzzy PID control algorithm into greenhouse environment regulation. Average packet loss rate of the system was 0.088%, average relative error of environmental factors such as temperature and humidity of air and soil, carbon dioxide concentration were kept within 0.5%. Sleep power consumption of NB-IoT was less than 9 μA. It realized intelligent feedback control and guaranteed performance and conditions of multinode deployment, multiparameter detection, low power consumption and wide coverage of communication. This made the system with higher adaptability and stability in complex environment.

Key words: IoT system, fuzzy PID control, NB-IoT, ZigBee, intelligent control