【作者】 郑颖航；

【导师】 丁天怀；

【作者基本信息】 清华大学 ， 机械电子工程， 2002， 硕士

【摘要】 棉花的含水率是影响棉花加工质量的一个关键参数，也是棉花加工质量监控系统中的一项重要控制参考量。为实现对棉花含水率的快速准确测量，本文提出了一种基于质量补偿的电阻式棉花水分测量方法，并进行了试验验证。在对一般的电阻式棉花水分测量原理分析的基础上，针对国内现有电阻式棉花水分测量仪无法满足现场在线测量及质量取样不均的现状，本文重点就基于质量补偿的电阻式棉花水分测量中的质量补偿、快速性、极板以及电阻测量方法进行研究。通过测量不同质量的棉花压紧时极板距离估算棉花的质量大小，并对测量结果进行质量补偿；将装置直接置于棉花管道中实现电阻式水分测量的快速性；采用多通道极板完成一次压紧同时测量多个点；测量棉花电阻与电容构成的RC回路对正弦信号的相位差得到实际棉花的含水率。设计并完成了一个基于Philips 80c552单片机的硬件测控平台，并用单片机80C51的C语言完成系统软件的编写。利用8253的计数功能测量通过棉花RC电路前后的两路信号的相位差完成对棉花含水率的测量；借助单片机的计算功能，利用AD590的电流随温度线性变化的特点测量温度，从而对测量结果进行温度补偿；利用3503U的电流随磁铁距离的线性变化特点测量极板位移，实现对测量结果的质量补偿；利用霍尔器件的磁敏特性实现了对电机运动位置的自动判断；棉花的自动压紧和松开由单片机控制交流异步电机实现；系统与棉花监控系统的主控主机相互间的的串行通信，具有了通过上位机自动测量的能力。完成了系统温度标定、极板距离标定、含水率标定的试验，校验了测量系统的可重复性，并通过试验拟合出了温度、质量对测量结果影响的公式。更多还原

【Abstract】 The moisture content of cotton, which has a significant effect on the process of cotton, is an important controlling parameter in the quality monitor system for process of lint. In order to measure the data of moisture content fleetly and truly, this paper developes a resistance-type measuring method for cotton moisture based on mass compensation, and completes the experimentation.On the basis of studying the traditional measuring resistance-type method for cotton moisture completely, in order to solve the problems include varied mass of cotton in filed measurement and on-line measurement, this paper researches four aspects of the measuring method, includes the compensation by the mass, the speediness, the design of the measuring board, and the measuring method of resistance. The system needs to compensate the moisture content by the mass with the measurement of the displacement of the measuring board, in which cotton with different mass is placed. It gains the speediness by fixing the equipment in the cotton tract. It measures several points once the compaction is completed. It obtains the cotton moisture by measuring the phase difference of the sine signals, one of which passes the RC loop composed by cotton and capacity.This paper designs a new hardware platform founded on the single-chip microcomputer named Philips 80c552, and completes the software by C Program Language for 80C51 single-chip microcomputer. The hardware platform can press out cotton by controlling an AC asynchronous motor. It can judge the situation of the movement of the motor with the magnetic sensitivity of Holl device. Utilizing the counter of the chipset 8253, the system can attain the cotton moisture by measuring the phase difference of the two signals. In virtue of the calculating function of the single-chip microcomputer, it compensates the reading with temperature obtained by AD590，whose output current is linear with the temperature, and with displacement gained by 3503U, whose output current is linear with the displacement. The system can be controlled to measure automatically by the main host computer of the quality monitor system with the serial<WP=6>communication.When the design for the software and hardware of the meter was finished, the system is tested by temperature calibration, mass calibration, and moisture calibration. The repeatable precision is also tested, and the formuna of the effect from temperature and mass on moisture is established.更多还原