Research On An In-situ Machine Vision Inspection System Of The Nick Depth Of Easy Open End

Abstract:The nick depth of easy open end is a key parameter in ensuring high packaging quality, but the present detection methods are unable to meet the requirements of industrial automation. To solve this problem and realize automatic detection of easy open end in industrial production sites, this paper presents a machine vision system based on light-section method and image processing technology. Following are the main contents in this paper:(1) Hardware design includes micro-vision system and4-axis motor execution system. According to detection demands, the digital eyepiece with1/2" CMOS image sensor with1.3million pixels was selected to renovate the9J light-section microscope; the best lighting scheme was realized using LED instead of incandescent lamp, which was designed with Tracepro software simulation; and the4-axis motor execution system was composed of a4-axis motion control card, four step motor divers and four electric displacement stations with step motors and RS232standard interfaces.(2) Software development includes the image measuring software and the3D automatic positioning software. The image measuring software was developed through VC++platform to realize the functions of image acquisition, preprocessing and measurement, in which an automatic blocking and threshold segmentation algorithm based on projection method was presented to achieve better segmentation effect. Then the3D automatic positioning software was developed to meet the demands of X-Y plane positioning, automatic focusing and rotating, in which a plane positioning algorithm for the nick section images and an automatic focusing algorithm based on the sum of gray-change function and Laplacian function were put forward to detect and adjust the image position in3D.(3) Experimental analysis was made on the measurement range, the measurement repeatability and the vibration characteristics of the vision system, and the results showed that the measuring range is (20-990)um, with the measurement uncertainty better than4%; shaking table with vibration frequency of6.7Hz and amplitude of360μm was used to simulate production environment of easy open end, and the system was verified to be effective in similar production environments.