摘 要

我国是一个粮食生产大国，粮食的含水量从收割、存储、运输、贸易、加工等过程都是一个重要因素，如果水分含量不合适容易引起霉烂变质，引发财产损失甚至食品安全问题。利用烘干机降低粮食水分是粮食安全存储、运输的重要环节，对降低我国粮食产后损失保持粮食的经济价值等具有十分重要的意义和广泛的市场需求。而检测粮食水分也是十分必要，根据粮食的含水量是否达到储藏要求，判断是否应该进行烘干处理。只有研究出低成本，高可靠性的在线测量装置才能够实现粮食烘干机的精确自动化控制，对于提高我国的粮食存储和运输安全性。

由于粮食水分的测量受到粮食温湿度、热风湿度和粮食重量变化等因素的影响，直接测量粮食的含水量比较困难，难以实现干燥过程水分在线测量的快速性机水分控制的精确性。而测量影响粮食含水量的这些间接因素很方便，间接法是通过测量与水分变化相关的物理变化, 如电阻 (电导率)、 介电常数、 对红外光谱的吸收特性、 对微波能的吸收特性和声学特性等来测量粮食水分含量的。本文着重讨论间接测量方法和在线测量技术。

考虑到电阻法在线检测粮食水分具有响应快速、结构简单、价格便宜和携带方便等特点。为达到粮食水分在线检测的目的，本次课程设计利用粮食水分与粮食电阻之间的函数关系，设计了一套粮食水分在线检测采集电路。

关键词：粮食水分，粮食电阻，在线检测，采集

Abstract

China is a large country of grain production, grain moisture are an important factor from harvesting, storage, transportation, trade, processing and other processes. It will cause property damage or food safety issues if the moisture content is not suitable for easily lead to mildew and rot. Reducing grain moisture by drying machine is an important part of food safety storage and transportation, and it is of great significance and broad market demand for reducing the economic value of grain after the loss of grain in China. The grain water detection technology is the former process of grain drying, grain drying machine according to the grain moisture content of the grain drying processing. To improve the security of grain storage and transportation in China, only by studying the low cost, high reliability of the online measurement device to achieve the accurate automatic control of grain drying machine.

The direct measurement of grain moisture content is difficult, due to the influence factors of grain moisture measurement by the grain temperature and humidity, air humidity and the grain weight changes. it is difficult to achieve the accuracy of online measurement of moisture content in drying process control machine water. Measuring of grain moisture content of these indirect factors is very convenient, indirect method is through measurement and moisture changes related to the physical changes, such as resistivity (conductivity), dielectric constant, the infrared spectrum absorption characteristics, the microwave energy absorption characteristics and acoustic characteristics and to measure the moisture content of grain. This paper focuses on the indirect measurement methods and online measurement techniques.

Taking into account the resistance method on line detection of grain moisture has the characteristics of fast response, simple structure, low price and easy to carry. In order to achieve the purpose of on-line detection of grain moisture, the course design and use the function relationship between grain moisture and grain resistance.

The key words: grain moisture, grain resistance, on-line detection, acquisition.

目录

1.1粮食水分在线检测的背景、目的及意义 1

1.2粮食水分检测国内外的发展现状 1

1.2.1水分检测方法概述 1

1.2.2粮食水分在线检测的国内外现状 4

第2章 粮食水分在线检测采集电路设计 6

2.1测量原理 6

2.2研究内容和方法 6

2.3总体设计方案 7

2.4水分仪的功能设计 7

2.5粮食水分检测仪的硬件电路设计 7

2.5.1电源模块设计 7

2.5.2信号采集电路设计 8

2.5.3信号放大电路设计 10

2.5.4数码管电路设计 11

2.5.5继电器控制电机电路 14

2.5.6功能按键电路设计 17

2.5.7 单片机控制系统设计 18

第3章 粮食水分检测系统的软件设计 21

3.1程序主函数 21

3.2按键控制子程序 22

3.3 信号采集子程序 23

3.4 数据处理子程序 24

3.5水分显示子程序 25

第4章 总结与展望 27

4.1总结 27

4.2展望 27

参考文献 28

致谢 29

第1章 绪论

1.1粮食水分在线检测的背景、目的及意义

古往今来，人类都离不开农业。对中国这个世界人口第一大国来说，农业就是国民经济的根本。为了实现我国综合国力和经济实力的提高，我国一直在探索农业发展道路，并在农业现代化、经济和社会方方面面都取得了巨大成就。

据统计，我国的粮食总产量近年大约有5亿吨，每年收货的高水分粮食多达20%，而一般储藏的粮食适宜水分为13%-14%^[1]。每年我国由于粮食处理不及时或，保存方式不正确或者检测水分手段有误差，约有10%的粮食在储藏、运输过程中霉烂变质，造成巨额损失，粮食损失重量高达百亿公斤^[2]。因此，必须要干燥粮食，使之达到能够安全存储和运输的要求，减少甚至不产生损失。