Resrerch On The Key Technology For Grain Depot Monitoring System Based On WSN

WSN-based monitoring system for grain depot is the sensor network that most sensor nodes are buried in the grain or deployed in the grain surface. Compared to using wired sensors technology for the monitoring system in large-scale barns, WSN-based technology has several outstanding advantages in easy deployment, multi-parameter monitoring and easy upgrade. Research of WSN technology for the monitoring system in large-scale barns has a great practical meaning to ensure grain quality and security. Based on the characteristics of the grain storage, we study on the technology of wireless sensor network application in grain monitoring in this paper. We design a wireless grain condition monitoring system, of which performance is proved to meet the grain monitoring requirements by test. The main contributions of this thesis are as follows:1. Design the hardware of wireless grain depot monitoring system node. By analyzing the requirements like accuracy of grain sensor, power consumption, communication performance, etc, we modularize the circuits by function and design circuits’schematic. At last, we complete the node, and experiences in the welding process of debugging have been summed up.2. Design the protocol and Implementation the software of wireless grain monitoring node. System protocol is divided into four layers: physical layer, MAC layer, network layer and application layer. On MAC layer, we analyze TPSN time synchronization algorithm, including synchronization accuracy, balance the energy consumption and system clock selection, the synchronous cycle. We also discuss the CSMA-CA algorithm and its implementation. On network layer, a protocol based on TDMA is designed. At last, we design appropriate protocol for application layer.3. Test the wireless grain monitoring system. Firstly, for estimating the system lifetime, we take three researches as follow:the quantitative method for calculating residual energy of battery, the daily energy consumption and network lifetime, measuring the voltage changes when the node in high-frequency work status. After analysis, we ensure that the wireless grain monitoring system can continuously work for1.5years. Secondly, with maximum transmitting power, the RSSI and packet loss rate with different distance curve have been drawn to show that the node point-to-point communication distance is more than200m. At last, it is been proved that wireless grain monitoring system can apply to monitoring grain storage, by the system deployed and tested in180t grain steel silos, the practice has proved that the system can apply to grain storage monitoring.