Reasearch On The Key Technique Of Structured Light System Measurement Based On Single Cylindrical Target

Visual measurement has become one of the key factors in the development of industrial automation.Among many visual measurement methods,structured light visual measurement has become one of the most widely used methods in industrial environment because of its wide measurement range,no contact,high speed and high precision.The solution of line structured light plane has a vital influence on the quality of line structured light vision measurement technology and the performance of the whole calibration algorithm.In this paper,based on the application of current line structured light measurement and considering some practical problems in industrial production,a method for determining the line structured light measurement system in complex industrial environment is proposed.In a complex industrial environment,because the calibration target is inconvenient to move,the target needs to be calibrated with as few images as possible.The 3D target method only needs one image to complete the entire calibration process,and has a certain calibration accuracy,which can meet the calibration requirements under complex lighting conditions,so it is selected as the key research object in this paper.Traditional 3D targets have higher production costs and technological requirements.The manufacturing process of 3D cylinderical is relatively simple and has special geometric characteristics.In addition,cylindrical targets have low requirements for feature points and contour features in complex environments.Therefore,a single cylinderical is selected as the 3D target in this paper.The main contents of this article include:(1)Industrial production pays attention to real-time performance,and traditional line structured light measurement emphasizes too much calibration accuracy and ignores industrial production efficiency.In order to quickly and accurately calibrate the light plane equation of the line structured light under a single cylinderical target,a calibration method for a line structured light vision sensor based on a single cylinderical target is proposed in this paper.Using the principle of perspective projection model,the relation equation of the corresponding projection image of the space ellipse formed by the intersection of line structured light and cylindrical target is established,the external parameters of the light plane are estimated,and the light plane equation is calculated.The effectiveness of the light plane method was verified by comparing the physical experiment with the light plane calibration method of the plane target.(2)Traditional line structured light measurement requires taking multiple pictures for camera calibration,which is not suitable for complex industrial background.In order to improve the above defects,this paper proposes a complete calibration method for structured light vision measurement system based on a single cylindrical target.The camera calibration and the line structured light calibration are combined with each other based on the geometry and spatial elliptic projection property of the cylindrical image captured by the camera.The internal parameters of the camera are obtained by making full use of the geometricalproperties of the cylinder.After the distortion correction,the obtained structured light strips are fitted with ellipses,and the line structured light plane equation is obtained according to the projection of the space elliptic as a standard circle.(3)In order to verify the feasibility of the measurement method studied in this subject,physical experiments and simulation experiments were proposed and designed for the single cylindrical target.The line structured light measurement system only needs a camera,a structured light projector and a cylindrical target.The experimental results show that the distance RMS error of the new calibration method is 0.070 mm when the measuring distance is about 1100 mm.It shows that the calibration method proposed in this paper can achieve higher calibration accuracy and measurement accuracy,and can meet the requirements of 3D measurement technology in general industrial environment,while greatly simplifying the algorithm steps of complete calibration.