摘要
为实现对大量元素水溶肥种类的快速准确辨识,根据水溶肥的介电特性设计了一个传感器,并在此基础上采用特征频率法,研制了一种大量元素水溶肥快速辨识装置,主要由±5V稳压电路、单片机控制电路、激励信号发生电路、传感器、真有效值转换电路和LCD显示模块组成。以市面上常见的尿素、普钙、硫酸钾、磷酸氢二铵、磷酸二氢钾和硝酸钾6种大量元素水溶肥作为试验对象,在1 kHz^10 MHz激励信号频率范围内研究了其频率响应特性,得出了9个用于辨识6种大量元素水溶肥的激励信号特征频率,即30、40、50、600、700、800 kHz和3、4、5 MHz。根据各种水溶肥分别在9个特征频率处的响应模式,设计了对6种大量元素水溶肥的辨识策略。该装置的辨识性能采用234组不同类型和浓度的待测水溶肥进行验证试验,结果表明:该装置的辨识准确率为98.3%,完成1次辨识的平均时间为14.3s,最长不超过19.5 s,表明该装置具有良好的快速性和准确性,满足实际应用要求。
In order to realize a rapid and accurate identification for types of macronutrient water soluble fertilizers,a rapid identification device was developed by using a characteristic frequency method on the basis of a sensor designed according to the dielectric properties of water soluble fertilizer.The device was mainly composed of a±5V voltage regulator circuit,a single chip microcomputer control circuit,an excitation signal generation circuit,a sensor,a true RMS（root mean square）conversion circuit and an LCD（liquid crystal display）display module.With 6 kinds of common macronutrient water soluble fertilizers on the market as research objects,and selecting the mass ratio of 1：30,1：1 000,and 1：3 000,the frequency response characteristics of 18 groups of macronutrient water soluble fertilizer samples were studied in a series of excitation signals,whose frequency range was from 1 to 10 MHz,which was divided into 1-100 and 100-1 000 kHz and 1-10 MHz.It was found that the characteristics frequencies of excitation signals for the 6 kinds of water soluble fertilizers,i.e.nitrogen,phosphorus,potassium,nitrogen and phosphorus,nitrogen and potassium,phosphorus and potassium,were 30,40,50,600,700 and800 k Hz,and 3,4 and 5 MHz.According to the response pattern of each kind of water soluble fertilizer at its characteristic frequency,the identification strategy of 6 kinds of macronutrient water soluble fertilizers was obtained.Whether the sensor electrode’s long-term work in the fertilizer was stable or not,would directly affect the device’s identification effect.In order to test the stability of sensor electrode,the samples of 3 concentrations i.e.1：10,1：100 and 1：1 000 were prepared.Respectively,the sensor electrode was immersed in the sample and its output voltage was monitored continuously for a month.The results showed that the maximum error of the sensor electrodes in the 3 kinds of samples was 0.28%,0.19%and 0.10%respectively for one month,which indicated that the sensor electrode would not affect
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2017年第6期51-58,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金(51509121)
云南省高校工程研究中心建设计划
关键词
传感器
肥料
频率响应
大量元素水溶肥
特征频率
快速辨识
辨识装置
sensors
fertilizers
frequency response
macronutrient water soluble fertilizers
characteristic frequency
rapid identification
identification device
