Key Dimensional Measurement Of The Right-side-box Skeleton Of Halfheight Security Doors Based On Machine Vision

Half-height safety doors are also called semi-closed screen doors,which are mainly used in rail transit platforms to ensure the safety of passengers.The fixed-sidebox is an important part of the half-height security doors.When measuring its size during the manufacturing quality inspection process,the traditional contact measurement method is usually used.At present,there are high costs,low efficiency,direct contact,and some sizes are not easy to directly measure.The dimension measurement method based on machine vision has the advantages of low cost,high efficiency,no direct contact and wide application range.This paper studies the measurement of the key dimensions of the right-side-box skeleton of the half-height safety doors based on machine vision,and develops a measurement system of the key dimensions of the right-side-box skeleton of the half-height safety doors.It has certain practical significance in engineering.The main research work of the paper is as follows:(1)In order to accurately obtain the pixel coordinates of the key points,the center pixel coordinates and the circle pixel radius from the picture of the object to be measured,the image of the object to be measured is first filtered,then the distortion is corrected,and finally the Shi-Tomasi algorithm and the sub-pixel refinement algorithm are used to obtain the sub-pixel pixel coordinates of key points,and use the Hough gradient method for circle detection to obtain the center pixel coordinates and the circle pixel radius.(2)A kind of measurement methods based on pixel equivalent is used to measure the key dimensions of the right-side-box skeleton of the half-height safety doors when the imaging plane is parallel to the measurement plane.The experimental results show that: the measurement method used in this paper can be used to measure the key dimensions of the right-side-box skeleton of the half-height safety doors,and the accuracy can meet the requirements better.(3)Aiming at the problem that when the imaging plane is not parallel to the measurement plane,adopting a globally uniform pixel equivalent will result in a large measurement error,a kind of measurement methods based on world coordinates is proposed.The experimental results show that: being compared to the measurement methods based on pixel equivalent,the measurement method based on world coordinates used in the measurement of the key dimensions of the right-side-box skeleton of the half-height safety doors has a small relative error and absolute error,and its standard deviation is smaller.(4)Based on Visual Studio,QT and OpenCV,a simple and easy-to-use dimensional measurement software is designed.This software can realize the visualization and modularization of the key dimensions of the right-side-box skeleton of the half-height safety doors.