Optical Dynamic Flowmeter Of Belt Conveyor Based On FPGA

For a long time,the belt conveyor has advantages of economy,reliability,flexible circuit and low energy consumption,so it has become the main equipment for transportation and loading and unloading of bulk materials in many industrial and agricultural production.The dynamic measurement data of conveying bulk materials by conveyor is of great significance to the information transformation,standardized management,automation control and improvement of product quality of enterprises.Therefore,improving the accuracy and intelligence of dynamic measurement of bulk materials has become a research focus in recent years.In order to rapidly,accurately,and stably measure bulk materials,based on Xilinx's zynq-7000 chips,we proposed an optical non-contacting dynamic metering system for volume flow,it has the advantages of fast metering speed,high precision,high stability,small error,automation and low cost.First of all,based on the analysis of the existing dynamic metering principle and device of bulk materials,we propose a non-contact measurement scheme,which is based on the contour detection model of structured light and dual camera,and designed the light path for the vision sensor.At the same time,we built a mathematical model of the measurement system based on the principle of perspective projection and the idea of integration,and we have established the method of conversion between 2d pixel coordinates and 3d world coordinates and the calculation method of material volume.Secondly,using the mathematical model of vision sensor,we presents the calibration method of the inner and outer parameters of the measuring system.Finally,the overall realization of the measurement system and the hardware and software design are completed.The hardware part is realized by the hardware logic resources of PL,which mainly includes image acquisition,image display,image processing,sub-pixel center extraction of optical strip,coordinate transformation,optical strip Mosaic,encoder ranging,volume calculation and other modules.The software part is implemented in PS,which includes the transplantation of Linux operating system,Open CV library and QT library,and we use QT to write the upper computer software of the system,in which the system calibration,measurement results display and other functions are realized.Based on the above research,we built a prototype of the measurement system in the laboratory,and carried out calibration experiments and flow measurement experiments with the prototype.The calibration experiment determines the focal length of the vision sensor,the main point of the image,the distortion coefficient,and the mathematical transformation relationship between the 2-d image coordinate system and the 3-dal world coordinate system.In addition,the volume flow of bulk materials was measured by the calibration results,and the measurement results and errors were analyzed,experiments show that the system can realize real-time,accurate,stable and automatic measurement of volume flow of bulk materials.