Design And Application Research Of Intelligent Sensor Based On Knitting Structure

As technology has improved,traditional mechanical sensors have shifted from materials like metals and semiconductors to lighter,more durable materials that are smaller and easier to carry.The flexible sensor of knitted structure has good stretch,flexibility and high elasticity due to its coil structure,which has great potential in the field of smart clothing and wearable devices.This project designs an intelligent flexible sensor based on knitted structure.On this basis,a wrist Angle monitoring system based on STM32 microcontroller is developed,which can realize the Angle recognition of human wrist.The research content is as follows:1.The selection of stainless steel blended yarn,copper plated yarn and silver plated yarn performance test,test the linear density,unit resistance and tensile breaking strength,explore the selected yarn braided;In the preliminary experiment,the conductive rib fabric with the same density was made with three different yarns selected,and the conductive fabric made with different raw materials was tested to determine the most suitable braided yarn for this experiment.A variety of different fabric fabrics with different densities were designed and prepared on a computer flat knitting machine by selecting the most excellent conductive yarns,which were used as conductive areas for knitted flexible sensors.2.Prepare ribbed fabric,ribbed semi-air layer fabric,ribbed air layer fabric,and conductive fabric with different fabric densities,and conduct experiments on their conductive properties to discuss the influence of fabric stitch and fabric density on conductive knitted fabric.A hexagonal equivalent resistance model was established,and the influence of different loop parameters and loop density on fabric conductivity was analyzed from fabric structure.3.The conductive fabric with the best conductive performance is selected to collect the size of the human wrist and make the knitted flexible sensor wristband to test its wear performance;The posture detection system based on STM32 microcontroller was developed,and the posture recognition was carried out by combining the knitted sensor wristband prepared.The results are as follows: The conductive fabric woven with copper plated yarn has obvious resistance variation and better continuity.In ribbed air layer stitch,ribbed half air layer stitch and ribbed fabric,the resistance of ribbed fabric is the largest when the transverse density of fabric is constant.In conductive fabrics of the same stitch with different course densities,the resistance difference is more obvious and the sensitivity is higher as the transverse density increases.The equivalent resistance model was established.From the fabric structure analysis,when the fabric material was the same,the denser the loop,the smaller the fabric resistance.The most suitable fabric for knitted flexible sensor analysis is 35r/5cm copper plated conductive fabric.The size of human wrist is collected to make knitted flexible sensor wristband.When the wrist bending Angle is 0,the resistance value is about 2k ohms,when the wrist bending Angle is 22.5 degrees,the resistance value is about 1.8k ohms,45 degrees,1.5k ohms,67.5 degrees.The resistance is about 1.2k ohms and about 1k ohms at 90 degrees.The knitted flexible sensor has good stability with δ of 0.232 and sensitivity between 2 and 3.A posture detection system based on STM32 microcontroller was developed.Combined with the knitted sensor wristband,the knitted sensor was used to recognize the posture of the subjects.According to the comparison between the measured data and the man-made measurement results,it is further demonstrated that the knitted flexible sensor can reflect the wrist bending index of the wearer.