Research And Design Of Twist Meter Based On DSP

At present,most of the detection of twist is still carried out using a hand twist meter and a semi-automatic twist meter based on a single chip.These devices can measure the twist and twist of the yarn.However,these twist meters in the measurement process will damage the structure of the yarn,and must have manual operation.In order to solve these problems,this topic based on the machine vision method using DSP processor to automatically detect the yarn twist,so that the process without manual operation,improve detection efficiency.The detected object in this paper is yarn,which is transported by transfer bells,using linear array camera shooting moving yarn,The analog data captured by the camera is stored in the FIFO in the FPGA after high-speed A / D conversion.When the FIFO reaches half full state,the FPGA triggers the DSP to read half of the data in the FIFO in the FPGA,and splits the read image into a complete picture in the DSP.Finally,after the algorithm processing,the DSP to calculate the image of the yarn twist number,and output through the serial port.This paper designs the system from the hardware and software two aspects of the system.Hardware design in accordance with the system design requirements were DSP,FPGA,high-speed A/D,linear camera and other hardware selection.Draw the PCB board by ourself,the PCB board will connect all the devices together.When drawing the PCB board,we need to draw other peripheral circuits are needed by the system to run,including power circuit,DSP reset circuit,DSP modulation circuit,DSP start mode selection switch and serial circuit.And the frequency divider circuit of the encoder is designed according to the actual analysis.The software is designed to program the FPGA and DSP respectively.FPGA software design is mainly to read the linear array camera data after through the A/D conversion,so the analysis of TLC5510 and TLS1401 chip control timing,according to its timing diagram for FPGA programming.DSP software designed to be interrupted after the trigger,through the EMIFA interface using EDMA3 high-speed read the half-full data in the FIFO of FPGA,read into the memory of the DSP after the median filter,Fourier transform,Gaussian low-pass filter,Fourier Leaf inverse transformation,binarization after the twist in the image to identify.Finally through the system test,the error of the number of twist of the obtained yarn and the actual twist of the yarn is very small,which proves that the design of the subject can meet the design requirements.