Research On Water Meter Verification And Sorting System Based On Machine Vision

The cold water meter is the main measuring instrument for daily water consumption of residents.The state stipulates that every water meter needs compulsory verification before use.At present,water meter verification mainly adopts manual reading method to verify water meter.The results of verification are easily affected by the working experience and physical condition of the inspectors,and it is necessary to install and unload water meter at each time of verification.Long working hours and inefficient verification can not meet the increasing demand for water meters brought about by urbanization.Therefore,it is particularly important to develop automatic water meter verification production line and improve the automation level of water meter verification industry.For this reason,this paper designs the whole scheme of the first water meter automatic verification production line in China,and studies the key visual verification system and visual sorting system.The main work and contributions are as follows:1.The overall scheme design of water meter automatic verification production line.Drawing lessons from the traditional structure of water meter manual verification platform,the overall scheme of the first domestic water meter automatic verification production line is designed.The whole detection system consists of five parts: visual verification system,visual sorting system,electrical control system,pipeline transmission system and information management system.2.Development of Water Meter Visual Verification System.Aiming at the problem of water meter pointer reading recognition,an improved "distance method" reading water meter pointer reading algorithm is proposed.Morphological algorithm is used to reduce the influence of bubbles on water meter dial and improve the pointer recognition rate.A correction algorithm of pointer reading is designed to solve the problem of pointer installation angle deviation and improve the accuracy of reading.Through the second part of water meter dial,the accuracy of reading is improved.Dimensional code recognition is used to acquire the water meter number and record the verification data,so that the verification results can be traceable and provide corresponding information for the visual sorting system.The realization of water meter visual verification system.Based on the visual calibration algorithm of water meter in this paper,the existing manual calibration table of a water meter factory in Zhengzhou is transformed into a visual-based automatic calibration table.Through the statistics of six months’ actual production data,the recognition rate of the visual verification system can reach more than 94%,which verifies the accuracy and practicability of the algorithm.The successful transformation of the calibration platform has laid a solid foundation for the development of visual calibration workstation for the later automatic calibration production line of water meters.3.Development of Water Meter Visual Sorting System.Firstly,the camera parameters were calibrated,and then the Eye-to-Hand hand-eye structure modelw was deduced.On this basis,the hand-eye calibration was carried out and the transformation matrix between the camera and the robot coordinate system was established.In order to get accurate grabbing coordinates of water meter,shape matching was used to locate the water meter roughly,then Canny operator was used to extract the edge of the water meter,circle fitting was used to determine the image coordinates of the grabbing center of the water meter,according to the results of hand-eye calibration,the actual grabbing coordinates were obtained,so as to realize the grabbing of the water meter.Using the existing ABB IRB1200 robot,the experimental platform of water meter visual sorting system was built,the robot operation interface was developed on VS platform,and the experiment of water meter positioning and grasping was completed on this platform.Experiments show that under complex background conditions,the positioning accuracy of the sorting system in this paper is less than 1 mm,which can meet the sorting requirements of water meters,and lay a foundation for the development of visual sorting station of the whole automatic verification production line of water meters in the later stage.