Design And Implementation Of An Online Fabric Moisture Monitor Based On Resistance Measurement

Moisture regain is an important technical indicator for descript the fabric’s drydegree, it has great influence on textile products quality. In modern printing anddyeing industry, cylinder drying machine is the most popular tool for drying wetfabric or textile. Under this process, textile is wound around the drying cylinder whilehigh-temperature steams is leaded into the cylinder, the textile will be dried uniformly.Literarily, in domestic printing and dyeing industry the energy consumption duringdrying process, accounts for30~40%of the whole thermal energy consumption. Forthe moisture regain is manually, so it is urgent to find a online and automatic way forcontrol the fabric moisture regain.Compared with some indirect methods, resistance method is more mature, highaccuracy, cheap cost, it meet the needs of moisture auto-controlling in domesticprinting and dyeing industry. The resistance method’s key is summary the relationshipbetween fabric moisture and fabric conductive, it calculate textile moisture throughtextile resistor. According to the fabric physical characteristics, textile resistoraffected by many factors, but domestic moisture meter did not consider the influenceof testing parameters on measurement of fabric resistance.This paper, at the beginning, reviews the fabric moisture absorptioncharacteristics and the importance of control moisture. According to the principle ofresistance method, single factor experiments are designed to research the influence ofpressure, voltage, etc. on the resistance of fabric, Since test conditions have greateffects on the resistance of fabric according to experimental results, they must beoptimized and strictly. The cotton, polyester cotton and jute’s calibration curve werefitted.In the moisture meter, the textile is connected to a variable resistor structure, theelectric circuit is supplied by a50V regulated power and send a voltage signal. Thevoltage signal is amplified to0~5V by a programmable gain amplifier circuit thatconstituted by AD8221precision instrumentation and ADG1611analog switch. The next step, the signal is fed into STC microcontroller after it has through a voltagefollower circuit. In the microcontroller, the signal start to analog-to-digital conversionand data processing. After this, dot matrix LCD screen display fabric moisture regainvalue and DAC0832chip output control signal. Main program, amplifier circuit gain,resistance-moisture regain conversion process, LCD screen display and control signalare compelled in modular software design. Meanwhile, reliability design is consideredon the general planning: a hard ware circuit power-filter, isolation, RF suppressionand grounding design, the software on the digital filter design and watchdog. Finally,verified the performance of the instrument, the experimental data show that the designof instrument is the expected design specifications.