Global Calibration Method for a Multi-Sensor Measurement System Based on Structured Light Stereo Vision

2012 ◽  
Vol 542-543 ◽  
pp. 684-689
Author(s):  
Jun Yi Lin ◽  
Kai Yong Jiang ◽  
Chang Biao Huang ◽  
Bin Liu
Keyword(s):  
Coordinate System ◽  
Stereo Vision ◽  
Measurement System ◽  
Structured Light ◽  
Local Coordinate System ◽  
Calibration Method ◽  
Global Coordinate System ◽  
Global Calibration ◽  
The Common ◽  
Sensor Measurement

The global calibration of multi-sensor measurement system is difficult to accomplish, usually, it needs external high-precision measurement equipment. A novel global calibration method based on common planar template is proposed. Stereo vision combined with laser linear-structured light is adopted to constitute a 3D vision sensor system (3DVSS). Stereo calibration of the 3DVSS can be finished by the planar template calibration method. For the global calibration of multiple vision sensors, it only needs a common planar template which is one of the planar templates can be seen synchronously by every camera in 3DVSS. The homography matrix between the coordinate systems of the 3DVSS and the common planer template can be calculated. The global coordinate is established in the common planar template, so the local coordinate system (LCS) of each 3DVSS can be transformed to the global coordinate system (GCS) through the common planar template. Two experiments have been used to test the proposed method, and the experimental results show that the proposed method is flexible and effective.

Consistent co-rotational framework for Euler-Bernoulli and Timoshenko beam-column elements under distributed member loads

2021 ◽  
pp. 136943322098663
Author(s):  
Yi-Qun Tang ◽  
Wen-Feng Chen ◽  
Yao-Peng Liu ◽  
Siu-Lai Chan
Keyword(s):  
Coordinate System ◽  
Stiffness Matrix ◽  
Traditional Method ◽  
Local Coordinate System ◽  
Frame Structures ◽  
Global Coordinate System ◽  
Single Element ◽  
Geometrically Nonlinear ◽  
Geometrically Nonlinear Analysis ◽  
Geometric Stiffness

Conventional co-rotational formulations for geometrically nonlinear analysis are based on the assumption that the finite element is only subjected to nodal loads and as a result, they are not accurate for the elements under distributed member loads. The magnitude and direction of member loads are treated as constant in the global coordinate system, but they are essentially varying in the local coordinate system for the element undergoing a large rigid body rotation, leading to the change of nodal moments at element ends. Thus, there is a need to improve the co-rotational formulations to allow for the effect. This paper proposes a new consistent co-rotational formulation for both Euler-Bernoulli and Timoshenko two-dimensional beam-column elements subjected to distributed member loads. It is found that the equivalent nodal moments are affected by the element geometric change and consequently contribute to a part of geometric stiffness matrix. From this study, the results of both eigenvalue buckling and second-order direct analyses will be significantly improved. Several examples are used to verify the proposed formulation with comparison of the traditional method, which demonstrate the accuracy and reliability of the proposed method in buckling analysis of frame structures under distributed member loads using a single element per member.

A Self-Calibration Method for Robotic Measurement System

1999 ◽  
Author(s):  
Chunhe Gong ◽  
Jingxia Yuan ◽  
Jun Ni
Keyword(s):  
Coordinate System ◽  
Measurement System ◽  
Calibration Method ◽  
Position Measurement ◽  
Robot Calibration ◽  
Robot System ◽  
Self Calibration ◽  
World Coordinate System ◽  
Robot Accuracy ◽  
Calibration Methods

Abstract Robot calibration plays an increasingly important role in manufacturing. For robot calibration on the manufacturing floor, it is desirable that the calibration technique be easy and convenient to implement. This paper presents a new self-calibration method to calibrate and compensate for robot system kinematic errors. Compared with the traditional calibration methods, this calibration method has several unique features. First, it is not necessary to apply an external measurement system to measure the robot end-effector position for the purpose of kinematic identification since the robot measurement system has a sensor as its integral part. Second, this self-calibration is based on distance measurement rather than absolute position measurement for kinematic identification; therefore the calibration of the transformation from the world coordinate system to the robot base coordinate system, known as base calibration, is not necessary. These features not only greatly facilitate the robot system calibration but also shorten the error propagation chain, therefore, increase the accuracy of parameter estimation. An integrated calibration system is designed to validate the effectiveness of this calibration method. Experimental results show that after calibration there is a significant improvement of robot accuracy over a typical robot workspace.

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.

A Real-Time and On-Line Visual System for Seamless Steel Pipe Linearity Measurement

2005 ◽  
Vol 295-296 ◽  
pp. 393-398
Author(s):  
C.J. Liu ◽  
Xue You Yang ◽  
Ji Gui Zhu ◽  
S.H. Ye
Keyword(s):  
Coordinate System ◽  
Real Time ◽  
Local Coordinate System ◽  
Steel Pipe ◽  
Sensor Calibration ◽  
Steel Pipes ◽  
Global Calibration ◽  
On Line ◽  
Linearity Error ◽  
Seamless Steel

Linearity is a very important parameter for seamless steel pipes. A real-time and on-line visual measurement system for seamless steel pipe linearity is presented. The system consists of several structured-light visual sensors. Each sensor can achieve the coordinate of the center of partial steel pipe in its local coordinate system. Through global calibration, all coordinates measured can be transformed into an integrated coordinate system. The linearity error of steel pipe can be assessed. This method can fulfill 100% on-line and real-time linearity measurement. A pair structure-light sensor is designed to improve accuracy and a suspension-wires method for sensor calibration and global calibration is used. Through experiments, it shows that the method not only meets the need of precise calibration but also significantly improves the efficiency and feasibility.

Study on Establishment and Transformation of Coordinate System of Steel Structure in 3D Software

2014 ◽  
Vol 501-504 ◽  
pp. 2541-2545
Author(s):  
Kai Sun ◽  
Lu Shuang Wei ◽  
Li Xuan ◽  
Lun Gang Zhou
Keyword(s):  
Coordinate System ◽  
3D Visualization ◽  
Local Coordinate System ◽  
Steel Structure ◽  
Structure Design ◽  
Global Coordinate System ◽  
3D Space ◽  
Steel Members ◽  
Safe Condition ◽  
3D Software

The 3D visualization design of steel structure under the CAD environment needs to work in the global coordinate system (WCS), but design of various steel members in the 3D space must be completed in the local coordinate system (UCS), so it is perplexing for the conversion and calculation between UCSi (i=1,2,3....n) and WCS. It is proved that the maize grains are not polluted and food production is in safe condition. The article describes classification of several common coordinate systems, discuss the method of setting up coordinates system. Describe the process of type convertion of coordinate system in steel structure design and detailing softwares, and explained the advantage of the application in the real world project.

Research on global calibration method for multi-camera visual measurement system

2016 ◽  
Author(s):  
Dongzhao Huang ◽  
Qiancheng Zhao ◽  
Yun Ou ◽  
Tianlong Yang
Keyword(s):  
Measurement System ◽  
Calibration Method ◽  
Visual Measurement ◽  
Global Calibration

Modeling and Calibration of Grid Structured Light Based 3-D Vision Inspection

1999 ◽  
Vol 122 (4) ◽  
pp. 734-738 ◽  
Author(s):  
Guangjun Zhang ◽  
Liqun Ma
Keyword(s):  
Mathematical Model ◽  
Coordinate System ◽  
Structured Light ◽  
Calibration Method ◽  
Experimental Results ◽  
Image Feature ◽  
Feature Analysis ◽  
Calibration Process ◽  
Vision Inspection ◽  
The Mathematical Model

The principle of structured light 3-D vision is introduced, and using projective and perspective transformations, the mathematical model of grid structured light based 3-D vision inspection is established in homogeneous coordinate system in this paper. Based on the image feature analysis of grid structured light, a calibration method of grid structured light based 3-D vision inspection is proposed, and experimental results are also presented. This method is easy, efficient and fast to carry out. It simplifies the calibration process while guaranteeing its accuracy. [S1087-1357(00)00703-6]

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