【作者】 李芳；

【导师】 刘少刚；

【作者基本信息】 哈尔滨工程大学 ， 机械电子工程， 2012， 硕士

【摘要】 根据统计结果，有75%的木制品问题是由于在木材干燥过程中对含水率的检测不准造成的。木材含水率是木材干燥过程中的一个关键参数，我国森林资源缺乏，人们对木制品的需求日益增加，对木材含水率的准确检测，减少木材资源的浪费，是我国面临的一项日益严峻的任务。本课题的目标是研究一种能够在线、实时、非接触的木材含水率检测系统，该系统能够高精度的检测出木材含水率。本文概述了国内外木材含水率检测方法及检测系统的现状和特点，根据木材含水率检测系统的功能需求，确定了本文研究的木材含水率检测系统的总体方案。确定单一平面电容传感器为检测系统的敏感元器件，建立它的数学模型并完成数值解法。借助有限元软件FlexPDE和Matlab数据拟合工具箱，建立微电容值和介电常数的函数关系式。微电容测量电路是检测系统的核心部分。本文分析比较了应用于微电容测量的模拟检测电路和数字检测电路的优缺点，设计了基于电容数字转换器AD7746的微电容测量电路。木材含水率检测系统的实时性主要表现在微电容测量电路能够将电容测量值快速的传递给上位机。利用I2C串行总线、单片机串口、Matlab串口接口实现检测系统的通信功能，设计能够实时传递数据、实时处理数据的软件程序。最后，制作、焊接和调试微电容测量电路，加工实验台，调试微电容测量电路程序，建立含水率检测基准，开发木材含水率检测软件并进行实验验证，结果表明本文研究的基于微电容测量的木材含水率检测系统准确可行。更多还原

【Abstract】 According to the statistical results,75%of the wood problems were caused by measuringthe moisture content incorrectly in wood drying process. Wood moisture content was a keyparameter in wood drying process. Measuring the wood moisture correctly and decreasing thewaste of wood resources were severe task that we confronted with, because of lacking offorest resources and the wood requirement increasingly. Aiming at designed a online、realtime and non-contact wood moisture measurement system, which measured wood accurately.The characteristics and situations of wood moisture measurement system as well as themoisture measurement methods were summarized in China and abroad. Based on the functionrequirement，the scheme was determined. The sensitive component of the system was singleplane capacitance sensor，established the mathematical model and the numerical solution.Relied on the FlexPDE software and the data fitting toolbox of Matlab, established thefunction between the capacitance value and the dielectric constant.The tiny capacitance detection was the key part of the measurement system. Bothadvantages and disadvantages of the simulation detection circuit and digital detection circuitwere analyzed and compared, designed the tiny capacitance detection circuit based on thecapacitance to digital converter AD7746.The real-time of moisture measurement system mainly relied on the tiny capacitancedetection circuit that passed to the host computer rapidly. Using I2C serial bus，Microcontroller serial port、serial port of Matlab to completed the communication ofmeasurement system, and designed software program which transferred data in real time,processed the data in real time.Finally, printed board, welded board, debugged circuit board, processed equipment,debugged program, established the wood moisture benchmark and also developed the woodmoisture measurement software were all illustrated in this paper. Experimental results showedthat the wood moisture measurement system based on the tiny capacitance detection wasaccurate and workable.更多还原