scholarly journals A Model of Diameter Measurement Based on the Machine Vision

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 187
Author(s):  
Qingchang Tan ◽  
Ying Kou ◽  
Jianwei Miao ◽  
Siyuan Liu ◽  
Bosen Chai
Keyword(s):  
Rotational Symmetry ◽  
Structured Light ◽  
Measurement Model ◽  
Optical Center ◽  
Machining Accuracy ◽  
Normal Vector ◽  
Shaft Diameter ◽  
Light Plane ◽  
Elliptic Cone

If the shaft diameter can be measured in-situ during the finishing process, the closed-loop control of the shaft diameter processing process can be realized and the machining accuracy can be improved. Present work studies the measurement of shaft diameter with the structured light system composed of a laser linear light source and a camera. The shaft is a kind of part with rotationally symmetric structure. When the linear structured light irradiates the surface of the shaft, a light stripe will be formed, and the light stripe is a part of the ellipse. Therefore, the in-situ measurement of the shaft diameter can be realized by the light stripe and the rotational symmetry of the shaft. The measurement model of shaft diameter is established by the ellipse formed by the intersection of the light plane and the measured shaft surface. Firstly, in the camera coordinate system, normal vector of the light plane and the coordinates of the ellipse center are obtained by the calibration; then, the equation of oblique elliptic cone is established by taking the ellipse as the bottom and the optical center of the camera as the top. Next, the measurement model of shaft diameter is obtained by the established oblique elliptic cone equation and theoretical image plane equation. Finally, the accuracy of the measurement model of shaft diameter is tested by the checkerboard calibration plate and a lathe. The test results show that the measurement model of shaft diameter is correct, and when the shaft diameter is 36.162mm, the speed is 1250r/min, the maximum average measurement error is 0.019mm. The measurement accuracy meets the engineering requirement.

scholarly journals Calibration Method for Line-Structured Light Three-Dimensional Measurements Based on a Single Circular Target

2022 ◽  
Vol 12 (2) ◽  
pp. 588
Author(s):  
Jun Wang ◽  
Xuexing Li
Keyword(s):  
Structured Light ◽  
Three Dimensional ◽  
Calibration Method ◽  
Optical Center ◽  
3D Measurements ◽  
Light Plane ◽  
Laser Projector ◽  
Dimensional Measurements ◽  
Intersection Points ◽  
Circular Target

Single circular targets are widely used as calibration objects during line-structured light three-dimensional (3D) measurements because they are versatile and easy to manufacture. This paper proposes a new calibration method for line-structured light 3D measurements based on a single circular target. First, the target is placed in several positions and illuminated by a light beam emitted from a laser projector. A camera captures the resulting images and extracts an elliptic fitting profile of the target and the laser stripe. Second, an elliptical cone equation defined by the elliptic fitting profile and optical center of the camera is established based on the projective geometry. By combining the obtained elliptical cone and the known diameter of the circular target, two possible positions and orientations of the circular target are determined and two groups of 3D intersection points between the light plane and the circular target are identified. Finally, the correct group of 3D intersection points is filtered and the light plane is progressively fitted. The accuracy and effectiveness of the proposed method are verified both theoretically and experimentally. The obtained results indicate that a calibration accuracy of 0.05 mm can be achieved for an 80 mm × 80 mm planar target.

scholarly journals Field Geometric Calibration Method for Line Structured Light Sensor Using Single Circular Target

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Tianfei Chen ◽  
Lijun Sun ◽  
Qiuwen Zhang ◽  
Xiang Wu ◽  
Defeng Wu
Keyword(s):  
Structured Light ◽  
Linear Equations ◽  
Calibration Method ◽  
Experimental Result ◽  
Normal Vector ◽  
Geometric Calibration ◽  
Light Plane ◽  
Light Sensor ◽  
Fitting Method ◽  
Circular Target

To achieve fast calibration of line structured light sensor, a geometric calibration approach based on single circular calibration target is proposed. The proposed method uses the circular points to establish linear equations, and according to the angle constraint, the camera intrinsic parameters can be calculated through optimization. Then, the light plane calibration is accomplished in two steps. Firstly, when the vanishing lines of target plane at various postures are obtained, the intersections between vanishing lines and laser stripe can be computed, and the normal vector of light plane can be calibrated via line fitting method using intersection points. After that, the distance from the origin of camera coordinate system to the light plane can be derived based on the model of perspective-three-point. The actual experimental result shows that this calibration method has high accuracy, its average measuring accuracy is 0.0451 mm, and relative error is 0.2314%. In addition, the entire calibration process has no complex operations. It is simple, convenient, and suitable for calibration on sites.

scholarly journals Coaxiality of Stepped Shaft Measurement Using the Structured Light Vision

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Chunfeng Li ◽  
Xiping Xu ◽  
Huiqi Sun ◽  
Jianwei Miao ◽  
Zhen Ren
Keyword(s):  
Structured Light ◽  
Least Square Method ◽  
Measurement Model ◽  
Least Square ◽  
Light Plane ◽  
Reference Axis ◽  
Stepped Shaft ◽  
Movement Distance ◽  
On Line ◽  
Structured Light Vision

A method is proposed to measure the coaxiality of stepped shafts based on line structured light vision. In order to solve the repeated positioning error of the measured shaft, the light plane equation solution method is proposed using movement distance and initial light plane equation. In the coaxiality measurement model, the equation of the reference axis is obtained by the overall least square method through the center point coordinates of each intercept line on the reference axis. The coaxiality error of each shaft segment relative to the reference axis is solved based on the principle of minimum containment. In the experiment, the coaxiality measurement method is evaluated, and the factors that affect the measurement accuracy are analyzed.

scholarly journals Surface Fitting for non-Grid Data from in-Situ Measuring Systems of Aero-engine Blade

2020 ◽  
Vol 206 ◽  
pp. 03023
Author(s):  
Qing Mao ◽  
Sen Wang ◽  
Shugui Liu
Keyword(s):  
Dynamic Performance ◽  
Surface Fitting ◽  
Data Conversion ◽  
Machining Accuracy ◽  
Nurbs Surface ◽  
Grid Data ◽  
Measuring Systems ◽  
Aero Engine ◽  
Engine Blade

High machining accuracy of aero-engine blade largely determines the carrying capacity, endurance, acceleration and the dynamic performance of the aero-engine, so a reliable machining error inspection and evaluation technique is imperative. In order to give a reliable error evaluation, the non- uniform rational B-spline (NURBS) technique is adopted to reconstruct the surface within a specified accuracy. Usually, data points measured from aero-engine blade are non-grid data in situ measuring systems. To overcome the difficulty of NURBS surface fitting from non-grid data, a new method based on data conversion is proposed, in which chord length parameterization and uniform parameter sampling are combined together to realize the data convertation, and subsequently hierarchical fitting strategy is applied to finish the NURBS surface reconstruction. The way proposed for data conversion is easy to realize, and by which gemetrical features of original measured data are also reserved well, which make the whole method outstanding in low time cost. Experimental results show that the method is fast, effective. The source code has been implemented in VC++, while the resulting pictures are constructed in Matlab with the obtained control points, knot vectors, and the orders.

scholarly journals Shaft Diameter Measurement Using Structured Light Vision

Sensors ◽  
2015 ◽  
Vol 15 (8) ◽  
pp. 19750-19767 ◽  
Author(s):  
Siyuan Liu ◽  
Qingchang Tan ◽  
Yachao Zhang
Keyword(s):  
Structured Light ◽  
Diameter Measurement ◽  
Shaft Diameter ◽  
Structured Light Vision

Light Plane Calibration Method Using Line Transformation for Line Structured Light Measurement

2021 ◽  
Vol 58 (2) ◽  
pp. 0212001
Author(s):  
翟鹏 Zhai Peng ◽  
崔海华 Cui Haihua ◽  
胡广露 Hu Guanglu ◽  
张益华 Zhang Yihua ◽  
靳宇婷 Jin Yuting ◽  
...  
Keyword(s):  
Structured Light ◽  
Calibration Method ◽  
Light Plane ◽  
Light Measurement

Welding robotic hand-eye calibration method based on structured light plane

2019 ◽  
Author(s):  
Fangkai Xu ◽  
Shengli Fan ◽  
Qingqing Yang ◽  
Chang Zhang ◽  
Yigang Wang
Keyword(s):  
Structured Light ◽  
Calibration Method ◽  
Robotic Hand ◽  
Light Plane

Research on Calibration Method of Linear Structured Light Vision Measurement System

2014 ◽  
Vol 644-650 ◽  
pp. 1234-1239
Author(s):  
Tao He ◽  
Yu Lang Xie ◽  
Cai Sheng Zhu ◽  
Jiu Yin Chen
Keyword(s):  
High Precision ◽  
Measurement System ◽  
Structured Light ◽  
Target Position ◽  
Calibration Method ◽  
Measurement Model ◽  
Sensor Calibration ◽  
Vision Measurement ◽  
Set Up ◽  
Structured Light Vision

This template explains and demonstrates how to design a measurement system based on the size of the linear structured light vision, the system could works at realized the high precision and fast measurement of the size of mechanical parts, and accurate calibration of the system. First of all, this paper set up the experimental platform based on linear structured light vision measurement. Secondly, this paper established a system of measurement model, and puts forward a new method of calibration of structured light sensor and set up the mathematical model of sensor calibration. This calibration method only need to use some gage blocks of high precision as the target, the target position need not have a strict requirements, and the solving process will be more convenient, much easier to field use and maintenance. Finally, measuring accuracy on the system by gage blocks with high precision is verified, the experiment shows that measurement accuracy within 0.050 mmin the depth of 0-80 - mm range. This system can satisfy the demands of precision testing of most industrial parts .with its simple calibration process and high precision, it is suitable for the structured light vision calibration.

scholarly journals Intact Flagellar Motor of Borrelia burgdorferi Revealed by Cryo-Electron Tomography: Evidence for Stator Ring Curvature and Rotor/C-Ring Assembly Flexion

2009 ◽  
Vol 191 (16) ◽  
pp. 5026-5036 ◽  
Author(s):  
Jun Liu ◽  
Tao Lin ◽  
Douglas J. Botkin ◽  
Erin McCrum ◽  
Hanspeter Winkler ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Electron Tomography ◽  
Rotational Symmetry ◽  
Flagellar Motor ◽  
Cell Axis ◽  
Ring Assembly ◽  
Flagellar Motors ◽  
Cryo Electron Tomography ◽  
Flagellar Rotation

ABSTRACT The bacterial flagellar motor is a remarkable nanomachine that provides motility through flagellar rotation. Prior structural studies have revealed the stunning complexity of the purified rotor and C-ring assemblies from flagellar motors. In this study, we used high-throughput cryo-electron tomography and image analysis of intact Borrelia burgdorferi to produce a three-dimensional (3-D) model of the in situ flagellar motor without imposing rotational symmetry. Structural details of B. burgdorferi, including a layer of outer surface proteins, were clearly visible in the resulting 3-D reconstructions. By averaging the 3-D images of ∼1,280 flagellar motors, a ∼3.5-nm-resolution model of the stator and rotor structures was obtained. flgI transposon mutants lacked a torus-shaped structure attached to the flagellar rod, establishing the structural location of the spirochetal P ring. Treatment of intact organisms with the nonionic detergent NP-40 resulted in dissolution of the outermost portion of the motor structure and the C ring, providing insight into the in situ arrangement of the stator and rotor structures. Structural elements associated with the stator followed the curvature of the cytoplasmic membrane. The rotor and the C ring also exhibited angular flexion, resulting in a slight narrowing of both structures in the direction perpendicular to the cell axis. These results indicate an inherent flexibility in the rotor-stator interaction. The FliG switching and energizing component likely provides much of the flexibility needed to maintain the interaction between the curved stator and the relatively symmetrical rotor/C-ring assembly during flagellar rotation.

Study on Surface Processing of Non-Rotational Symmetry

2015 ◽  
Vol 1094 ◽  
pp. 348-351
Author(s):  
Er Hong Zhang ◽  
Hua Long Zhang
Keyword(s):  
Tool Path ◽  
High Efficiency ◽  
Rotational Symmetry ◽  
Machining Accuracy ◽  
Surface Machining ◽  
Factors Affecting ◽  
Microstructure Simulation ◽  
Slow Tool Servo ◽  
Theory Research ◽  
Simulation Systems

This paper studies on technology of slow tool servo method and the processing of high efficiency. High precision surface NRS goal is studied for factors affecting theNRSworkability and surface machining accuracy. Including slow tool servo theory, research tools, tool path generation, surface microstructure simulation, slow tool servoNRSsurface machining and simulation systems development, installation errors and adjustment tool,Yto linear turret design,NRSsurface machining experiments.

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