The Research And Experientation Of The Resistance-type Measuring Method For Cotton Moisture Based On Mass Compensation

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 serialcommunication.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.