便携式土壤湿度检测装置用于精准灌溉决策系统

采用最先进的技术进行精准灌溉是现代农业发展的必然趋势,但在准确预测被监测区域的土壤湿度时,面临一个两难的处境:少量土壤湿度固定检测点不能良好地反映作物区域土壤墒情信息,而大量布置传感器检测点又使得投资成本较大。因此该文设计了一种便携式土壤检测装置,同时基于该装置构建了一个精准灌溉决策系统,并把该系统应用于田间的精准灌溉决策。该系统由便携式土壤湿度检测装置和上位机决策软件2部分组成,其中便携式土壤湿度检测装置由FDR原理土壤水分传感器MS-10、低功耗单片机C8051F410、蓝牙无线传输模块、数据显示模块以及部分外围电路组成,可以独立实现时间记录、数据存储和实时显示。经过试验标定,装置的允许最大误差为2.2%,设计精度为95%;上位机决策软件分为数据接收模块、分布式二进制一致性算法模块和系统操作界面3个子模块,分别采用Visual Basic、Matlab和Matlab GUI设计而成,实现对便携式装置所采集数据的无线传输、归一化处理和数据融合处理,能够根据不同区域划分和不同作物灌水下限进行相应的运算,从而得到估计精度较高、区域大小可调的多尺度精准灌溉决策信息。最后通过30 m×30 m草坪的土壤湿度为检测参数的田间验证,该系统的平均决策准确率大于90%,且可以根据需要增减检测点个数。因此既可以独立应用,也可以作为固定检测方式的有效补充,实现作物区域土壤湿度信息的精确采集,有效提高水资源利用率。

Portable detection device of soil moisture for precision irrigation decision system

Precision irrigation by applying state-of-the-art techniques is an unavoidable trend for modern agriculture, but the dilemma is faced for predicting the soil moisture of a given crop area: Arranging limited number of soil detection sensors may not able to capture the whole information well, but adding sensors means increased investment costs. Hence, in this paper, a new soil moisture decision system by using portable detection device was designed and put into field-testing. The detection system can be decomposed into the portable soil moisture detection device and the host computer decision software. And the portable soil moisture detection device was designed with the soil moisture sensor MS-10 which follows the FDR principle, the C8051F410 low power consumption Micro-controller, the Bluetooth wireless transmission module, the data display module and the peripheral circuit. This hardware owns several useful functions such as time recording, data storage, data transmission and real-time display by LED. All these units are well organized to reduce the volume and weight of the device, which makes it easier to operate in the field. After experimental calibration and the field tests, the maximum allowable error and the design accuracy of this portable detection device were 2.2% and 95%, respectively. Meanwhile the software in PC is composed of the data receiving module, the distributed binary consensus algorithm module and the system operation interface. These sub-modules are developed by Visual Basic, Matlab and Matlab GUI, respectively. For the data collected by the portable device, firstly, it can be transmitted from the portable device to the upper computer through the data receiving module with wireless Bluetooth transmission mode; Then, it can be normalized as two states (state "0" and "1") by the normalization method through compared with the set irrigation low limit; The third, the distributed binary consensus algorithm module is used to compute the total and the local decision results according to these data which comes from at the same time; and finally, the decision results can be displayed on the system operation interface as pictures and symbols. In addition, this software can obtain multi-scale and adjustable decision results with higher estimation accuracy if several key parameters in the distributed binary consensus algorithm are optimized by the genetic algorithm (GA). By using the bio-inspired operators such as mutation, crossover and selection, high-quality solutions can be generated efficiently for the optimization and searching problems encountered in our application. Several field tests for the designed decision system are implemented on a 30 m×30 m lawn, the results showed that the system had several advantages, such as high accurate predication (the average accuracy rate of simulation test is about 98% when data is more than 63 and the average accuracy rate of experiment tests is above 90%), lower power cost and strong extendibility. In addition, this system not only can be used independently, but also can be used as an effective complement for the classical fixed detection method. Consequently, this system improves the utilization rate of water resources effectively by means of measuring the soil moisture content accurately, reliable data wireless transmission and fast parallel computation.