山地橘园无线环境监测系统优化设计及提高监测有效性

Optimal design of wireless monitoring system in mountain citrus orchard and improvement monitoring

针对山地橘园生长环境时空变异大,气候复杂多变的情况,对山地橘园无线监测系统进行了优化设计及试验,以实现橘园生长环境信息的有效监测。设计了适合山地橘园环境工作的信息帧结构,引入了双向指令控制机制,节点拓扑发现,路由监测以及节点信息多样化采集优化机制,以增强山地环境下橘园信息采集的鲁棒性和可控性。对橘园无线信道衰减情况进行了测试,引入阻挡和雨衰因子建立无线信道衰减模型,并用于指导橘园无线监测网络部署试验。无线信道衰减分析与网络部署试验结果表明,在复杂气候条件下,系统天线部署高度在1.5m,单跳通信距离在30m内,可较好地完成山地橘园环境信息采集和传输任务。744h的连续监测运行试验数据表明,优化设计后的无线监测系统信息传输成功率得到了提高,30m距离内的传输成功率在99.12%以上,监测系统工作稳定,运行良好,适于野外条件下山地橘园生长环境无人远程实时监测工作。

In order to monitor in real time the growth environment of a mountain citrus orchard and its variation with spatio-temporal and weather status, the optimal design and evaluation of a wireless monitoring system in a mountain citrus orchard was introduced in this paper. The wireless monitoring system is comprised of end nodes used for obtaining citrus growth environment information including air temperature, air humidity, soil moisture and light; router nodes used to relay citrus growth environment information; and a network coordinator, which performs functions such as managing the nodes, collecting and analyzing the data received from the end nodes, and connecting as a gateway for remote data access. CC2530 is adopted as the core processor of the monitoring system; it has the capability of wireless communication and central processing. The optimal design was introduced in this system including information frame structure suitable for a mountain orchard environment, bidirectional instruction control function, topology discovery, routing monitoring mechanism and node information diversification collection mechanism, so as to effectively enhance the robustness and controllability of monitoring the citrus orchard environment. In this paper, the citrus orchard in the subtropical garden of SCAU （South China Agriculture University） was selected for the test. The orchard hill has sloping terrain; citrus trees are planted by terraced distribution. The average slope is 20 degrees, the citrus trees have a height of 2.8m, their shrub diameters are 3m, and the average spacing of citrus plants is 2.8m. The citrus orchard wireless channel was measured in citrus orchard, and the wireless channel model was established through blocking factor and rain attenuation factor, it was used to guide the evaluation of the wireless monitoring network. Experimental results of RSSI （Receiver Signal Strength Index） and communication quality under different distances and climates show that reliable collection and transmission were available in the mountain citrus orchard when the wireless system was deployed with an antenna height of 1.5m and a maximum single-hop communications distance of 30m. Continuous 744h online test results show that the optimized wireless monitoring system improved the transmission success rate; it has a success rate of at least 99.12% for data transmission within the 30m distance. The system ran well, worked stably, and was suitable for the remote, real-time monitoring of the citrus growth environment in a mountainous orchard.