Research On Position Measurement Technology Of Steel Arch Based On Binocular Vision

During the tunneling process,the steel arch need to be spliced into loops to support the excavated tunnel sections.However at present,in most cases,the steel arch centering is spliced by manual work,which is consuming more time and energy,and cannot guarantee the splicing precision.In order to automatically splicing steel arches,this paper mainly uses binocular vision as a research method to study the measurement scheme of steel arches.The main research contents of this paper are:1)According to the needs of the project,a binocular vision measurement scheme is designed.The structural parameters of the scheme are analyzed and the appropriate parameter values are selected,and then the hardware selection and algorithm flow in the scheme are determined;2)Analyzed the camera imaging model and the principle of camera calibration,the flexible camera calibration proposed by Zhengyou Zhang was used to calibrate the binocular camera;3)The extraction algorithm of feature points in images is studied.In this paper,the center of the bolt hole on the end plate of the steel arch is used as the measurement feature point.Therefore,based on the existing common algorithms,this paper proposes a through-hole recognition algorithm based on elliptic features,an improved region growing method whose criterion is optimized,and ellipse fitting algorithm based on RANSAC algorithm.The feasibility of the algorithm is verified by experiments;4)Based on the extracted feature point coordinates,the description method of the overall pose of the steel arch based on the Euler angle method is analyzed.Moreover,for the two sets of steel arch attitudes,the calculation method of the attitude transformation matrix which minimizes the average error is derived;5)The experiment verified the feasibility of the measurement scheme and analyzed the accuracy of the experimental results.The analysis of the experimental results shows that when the deflection angle of the connecting plate and the imaging plane of the camera does not exceed 35~°that is the deflection angle of the design of the scheme,the measurement accuracy of the scheme in the plane direction is 0.2 mm,and the measurement accuracy in the depth direction is 0.6mm,the result meets the needs of the subject.