• 전자공학회논문지SC
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• 제47권6호
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• pp.80-85
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• 2010

현재 BGA 409 chip의 외관검사는 대부분 현미경을 이용한 육안검사로 이루어지고 있다. 그러나 인간의 시력에 의존하여 검사하는 현재의 외관검사 방법은 검사자의 육체적, 정신적 부분에 의하여 검사 결과가 변화하기 때문에 안정적인 결과를 기대하기 어렵다. 따라서 육안검사 시 발생하는 문제점을 개선하기 위해 BGA 솔더볼 외관검사의 비전 시스템이 개발 되었고, 이는 기존의 검사 방법에 비해 BGA 409 chip의 솔더볼의 외관검사의 신뢰성과 효율성을 증가시켰다. 하지만 BGA 솔더볼의 크기가 미세하고 그 특징의 구분이 힘들어 검사의 정확도가 떨어지고 오리엔테이션 오류가 발생하였다. 이에 본 논문에서는 BGA 솔더볼 외관검사의 정확도를 향상시키기 위해 에지 검출 알고리즘의 보완과 특징들만을 비교하는 패턴매칭 기법을 제안하였으며, 또한 특징 공간 설정의 기준이 되는 기준 영역의 개선을 통해 오리엔테이션 오류의 개선을 제안하였다. 즉, 본 논문에서는 기존의 비전 시스템의 정확도와 오리엔테이션 오류를 개선하는 방법을 제안함으로써 BGA 솔더볼 외관검사의 정확도를 향상시켜 결과적으로 BGA 솔더볼 외관검사의 에러율을 줄이고 검사 속도의 향상 등 기존의 외관검사 방법에 비해 향상된 검사 결과를 획득하였다.

• 제어로봇시스템학회논문지
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• 제9권10호
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• pp.774-781
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• 2003

The important factors that cause position error in X-Y robot are inertial force, frictions and spring distortion in screw or coupling. We have to estimate these factors precisely to correct position errors, Which is very difficult. In this paper, we makes systems to inspect metal stencil which is used to print solder paste on pads of SMD of PCB with low precision X-Y robot and vision system. To correct position error that is caused by low precision X-Y robot, we defines position error vector that is formed with position of objects that exist in reference and camera image. We apply MHT(Modified Hough Transformation) for the aim of determining the dominant position error vector. We modify reference image using extracted dominant position error vector and obtain reference image that is the same with camera image. Effectiveness and performance of this method are verified by simulation and experiment.

• 한국건설관리학회논문집
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• 제25권2호
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• pp.69-80
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• 2024

Currently rebar spacing inspection is carried out by human inspectors who heavily rely on their individual experience, lacking a guarantee of objectivity and accuracy in the inspection process. In addition, if incorrectly placed rebars are identified, the inspector need to correct them. Recently, laser scanning and AR technologies have been widely used because of their merits of measurement accuracy and visualization. This study proposes a technology for rebar spacing inspection and fixing by combining laser scanning and AR technology. First, scan data acquisition of rebar layers is performed and the raw scan data is processed. Second, AR-based visualization and fixing are performed by comparing the design model with the model generated from the scan data. To verify the developed technique, performance comparison test is conducted by comparing with existing drawing-based method in terms of inspection time, error detection rate, cognitive load, and situational awareness ability. It is found from the result of the experiment that the AR-based rebar inspection and fixing technology is faster than the drawing-based method, but there was no significant difference between the two groups in error identification rate, cognitive load, and situational awareness ability. Based on the experimental results, the proposed AR-based rebar spacing inspection and fixing technology is expected to be highly useful throughout the construction industry.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.748-754
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• 1994

This paper deals with a geometric error simulator, measurement and inspection of workpiece errors on the machine tools, and identification and compensation methodology of thermal errors in machining centers. In order to raise the machining accuracy of workpieces a measurement and inspection system on the machine tool is developed. By using MPPGT module Manual and CNC type CMMs are realized on the machining centers. To compensate for geometric and thermal deformation errors of machining centers, a real time and an off line geometric adaptive control system were developed on the machining centers. A vertical and a horizontal machining center equipped with FANUC 0MC were used for experiments. Performance of the systems were confirmed with a large amount of experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.140.2-140
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• 2001

In this paper, we develop the system which inspects the metal mask using area scan camera and belu type xy-table and introduce its inspection algorithm. Thes whole area of the metal mask is divides into several inspection block and the sixe of a inspection block is decided by FOV(Field of View). To compare with the camera image of each block, the reference image is made by gerber file. The ratation angle of the metal mask is calculated through the linear equation that is substituted two end points of horizontal boundary of a specific hole in a camera image for. To calculate the position error caused by belt type xy-table, hough-transform using the distances among the holes in two images os used. The center of the reference image is moved as much as the calculated position error to be coincide with the camera image ...

• 한국정밀공학회지
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• 제14권11호
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• pp.84-92
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• 1997

The purpose of this study is to develop a geometric error model and path compensation algorithm for rotating axes of the 5-axis machine tools, by a method to calibrate a rotary table using one master ball and three LVDTs. It was developed a new methodology to measure 3 translation errors of the rotary table and with a compensation procedure for setup errors of the master ball. The method is experimentally verified using a ball-table and on-machine inspection method. The results showed that the geometric error models with the path compensation strategy can be practically used as a means for improving the accuracy of the machine tools with rotary table.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1995년도 춘계학술대회논문집
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• pp.3-14
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• 1995

To investigate the effect of illumination conditions on visual inspection performance for TV panel glasses, three dependent variables, inspection time, error, and preference , were measured and analyzed through two consecutive experiments. The first experiment for reflection inspection was conducted using two independent variables, position and brightness. The second experiment for transparent inspection was made using two independent variables, height and brightness. The summary of the results of the experiment for reflection inspection are as follows ; The inspection performance of the position right above the subject (Position 1) was the best among the conditions in terms of errors, while the performance of the position slightly in front of and above the subject(Position 2) was the best in terms of inspection times. Inspection time was statistically different according to the brightness conditions specifically at the position in front of the subject(Position 3). The results of the second experimen for transparent inspection are that the inspection performance at medium height (Height 2) was the best among the three conditions in terms of errors while the performance at lower height(Height 3) was the best in subject preference. Based upon both results with respect to actual field conditions, two alternative inspection station designs were proposed for each lighting conditon.

• 대한임베디드공학회논문지
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• 제18권3호
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• pp.117-124
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• 2023

In the machine vision inspection equipment, diameter measurement is important process in inspection of cylindrical object. However, machine vision inspection equipment requires complex algorithm processing such as camera distortion correction and perspective distortion correction, and the increase in processing time and cost required for precise diameter measurement. In this paper, we proposed the algorithm for diameter measurement of cylindrical object using the laser displacement sensor. In order to fit circle for given four input outer points, grid search algorithms using root-mean-square error and mean-absolute error are applied and compared. To solve the limitations of the grid search algorithm, we finally apply the singular-value-decomposition based circle fitting algorithm. In order to compare the performance of the algorithms, we generated the pseudo data of the outer points of the cylindrical object and applied each algorithm. As a result of the experiment, the grid search using root-mean-square error confirmed stable measurement results, but it was confirmed that real-time processing was difficult as the execution time was 10.8059 second. The execution time of mean-absolute error algorithm was greatly improved as 0.3639 second, but there was no weight according to the distance, so the result of algorithm is abnormal. On the other hand, the singular-value-decomposition method was not affected by the grid and could not only obtain precise detection results, but also confirmed a very good execution time of 0.6 millisecond.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2000년도 추계학술발표논문집
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• pp.217-234
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• 2000

Approximately normalized control charts, called Q charts, have been given Quesenberry(1991) for charting in process of short-run, job-shop, etc. We consider a Q chart with inspection error for job-shop floor under geometric distribution, which can be used for processes when a fraction nonconforming is very small. Our results would be applied for designing other control charts with inspection error.

• 한국기계가공학회지
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• 제2권2호
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• pp.67-74
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• 2003

This paper presents the development of the Inspection machine for SMD mounted on cream solder of PCB. There are mounting errors of SMD such as misalignment, missing part, wrong orientation, wrong polarity and so on. The main hardware of the system consists of a machine vision part and a motion control part. Operating software has been developed in GUI environment to help user convenience. The Inspection Jobs consist of two procedures, that is, creation of the inspection reference data and automatic inspection. The Inspection reference data has a tree structure of linked list including PCB information, blocks, components, windows, and inspection methods. This paper presents versatile inspection methods which include a section length method, a projection method and histogram method. Therefore, user can choose the suitable procedure for various components. Finally, the automatic Inspection procedure using the reference data checks the mounting errors of components.