Accurate profile measurement method for industrial stereo-vision systems

Sensor Review ◽  
2020 ◽  
Vol 40 (4) ◽  
pp. 445-453
Author(s):  
Yang Zhang ◽  
Wei Liu ◽  
Yongkang Lu ◽  
Xikang Cheng ◽  
Weiqi Luo ◽  
...  
Keyword(s):  
Stereo Vision ◽  
Measurement Method ◽  
Vision System ◽  
Practical Implication ◽  
Image Features ◽  
Reference Points ◽  
Profile Measurement ◽  
Surface Boundary ◽  
Content Type ◽  
Profile Reconstruction

Purpose Profile measurement with boundary information plays a vital role in the detection of quality in the assembly of aviation parts. The purpose of this paper is to improve the evaluation accuracy of the aerodynamic shapes of airplanes, the profiles of large-sized parts need to be measured accurately. Design/methodology/approach In this paper, an accurate profile measurement method based on boundary reference points is proposed for the industrial stereo-vision system. Based on the boundary-reference points, the authors established a priori constraint for extracting the boundary of the measured part. Combining with the image features of background and the measured part, an image-edge compensation model is established to extract the boundary of the measured part. The critical point of a laser stripe on the edge of the measured part is extracted corresponding to the boundary constraint. Finally, as per the principle of binocular vision, the profile of the measured part is reconstructed. Finding Laboratory experiments validate the measurement accuracy of the proposed method which is 0.33 mm. In the analysis of results between the measured data and the theoretical model, the measuring accuracy of the proposed method was found to be significantly higher than that of the other traditional methods. Practical implication An aviation part was measured in the part-assembly shop by the proposed method, which verified the feasibility and effectiveness of this method. The research can realize the measurement of smooth surface boundary which can solve existing profile reconstruction problems for aviation parts. Originality/value According to the two-dimensional contour constraint, critical points of the laser strip sequence at the edge of measured part are extracted and the accurate profile reconstruction with the boundary is realized.

A field measurement method for large objects based on a multi-view stereo vision system

2015 ◽  
Vol 234 ◽  
pp. 120-132 ◽  
Author(s):  
Zhenyuan Jia ◽  
Lingli Wang ◽  
Wei Liu ◽  
Jinghao Yang ◽  
Yang Liu ◽  
...  
Keyword(s):  
Stereo Vision ◽  
Field Measurement ◽  
Measurement Method ◽  
Vision System ◽  
Stereo Vision System

The visual tracking system using a stereo vision robot

2014 ◽  
Vol 31 (8) ◽  
pp. 1790-1799 ◽  
Author(s):  
Long-Jyi Yeh ◽  
Tsung Han Lee ◽  
Kuei-Shu Hsu
Keyword(s):  
Real Time ◽  
Stereo Vision ◽  
Vision System ◽  
Moving Object ◽  
Hand Tracking ◽  
Moving Target ◽  
Content Type ◽  
3D Environment ◽  
Stereo Vision System ◽  
Normal Environment

Purpose – The purpose of this paper is to use vision stereo to simultaneously acquire image pairs under a normal environment. Then the methods of moving edges detection and moving target shifting are applied to reduce noise error in order to position a target efficiently. The target is then double confirmed via image merge and alignment. After positioning, the visual difference between the target and the image created by the stereo vision system is measured for alignment. Finally, the image depth of the target is calculated followed by real-time target tracking. Design/methodology/approach – This study mainly applies Sobel image principle. In addition, moving edges detection and moving target shifting are also used to work with system multi-threading for improving image identification efficiency. Findings – The results of the experiment suggest that real-time image tracking and positioning under a pre-set environment can be effectively improved. On the other hand, tracking and positioning are slightly affected under a normal environment. Errors of distance measurements occur because there is more noise existing. Research limitations/implications – This study mainly determines the movements and positioning of an object or a target via image. However, the stability of moving edges detection executed by the stereo vision system can be affected if the light sources in an environment are too strong or extreme. Practical implications – So far the method of tracking and positioning a moving object has been applied to surveillance systems or the application which requires measuring and positioning under a normal environment. The method proposed by this study can also be used to construct a 3D environment. Originality/value – The method proposed by this study can also be used to construct a 3D environment or tracking moving object to measure the distance.

scholarly journals Improving the performance of double-plane stereo vision system calibration, using a virtual plane

2010 ◽  
Vol 1 (2) ◽  
Author(s):  
Paweł Rotter ◽  
Witold Byrski ◽  
Michał Dajda ◽  
Grzegorz Łojek
Keyword(s):  
Stereo Vision ◽  
Vision System ◽  
Maximum Error ◽  
Reference Points ◽  
System Calibration ◽  
3D Space ◽  
Stereo Vision System ◽  
Virtual Plane ◽  
Calibration Pattern ◽  
Double Plane

AbstractIn the double-plane method for stereo vision system calibration, the correspondence between screen coordinates and location in 3D space is calculated based on four plane-to-plane transformations; there are two planes of the calibration pattern and two cameras. The method is intuitive, and easy to implement, but, the main disadvantage is ill-conditioning for some spatial locations. In this paper we propose a method which exploits the third plane which physically does not belong to the calibration pattern, but can be calculated from the set of reference points. Our algorithm uses a combination of three calibration planes, with weights which depend on screen coordinates of the point of interest; a pair of planes which could cause numerical errors receives small weights and have practically no influence on the final results. We analyse errors, and their distribution in 3D space, for the basic and the improved algorithm. Experiments demonstrate high accuracy and reliability of our method compared to the basic version; root mean square error and maximum error, are reduced by factors of 4 and 20 respectively.

scholarly journals Stereo Vision System for Vision-Based Control of Inspection-Class ROVs

2021 ◽  
Vol 13 (24) ◽  
pp. 5075
Author(s):  
Stanisław Hożyń ◽  
Bogdan Żak
Keyword(s):  
Stereo Vision ◽  
Feature Matching ◽  
Control Method ◽  
Vision System ◽  
Image Features ◽  
Image Feature ◽  
Stereo Pair ◽  
Navigation Systems ◽  
Stereo Vision System ◽  
Vision Based Control

The inspection-class Remotely Operated Vehicles (ROVs) are crucial in underwater inspections. Their prime function is to allow the replacing of humans during risky subaquatic operations. These vehicles gather videos from underwater scenes that are sent online to a human operator who provides control. Furthermore, these videos are used for analysis. This demands an RGB camera operating at a close distance to the observed objects. Thus, to obtain a detailed depiction, the vehicle should move with a constant speed and a measured distance from the bottom. As very few inspection-class ROVs possess navigation systems that facilitate these requirements, this study had the objective of designing a vision-based control method to compensate for this limitation. To this end, a stereo vision system and image-feature matching and tracking techniques were employed. As these tasks are challenging in the underwater environment, we carried out analyses aimed at finding fast and reliable image-processing techniques. The analyses, through a sequence of experiments designed to test effectiveness, were carried out in a swimming pool using a VideoRay Pro 4 vehicle. The results indicate that the method under consideration enables automatic control of the vehicle, given that the image features are present in stereo-pair images as well as in consecutive frames captured by the left camera.

Automatic multi-stereo-vision reconstruction method of complicated tubes for industrial assembly

2016 ◽  
Vol 36 (4) ◽  
pp. 362-375 ◽  
Author(s):  
Peng Jin ◽  
Jian Hua Liu ◽  
Shao Li Liu ◽  
Xiao Wang
Keyword(s):  
Stereo Vision ◽  
Measurement Method ◽  
Automatic Measurement ◽  
Point Clouds ◽  
Geometric Error ◽  
Reconstruction Method ◽  
Control Points ◽  
Content Type ◽  
Measurement Results ◽  
Adjacent Line

Purpose Complicated tubes extensively exist in the industrial equipment. The manufacturing precision of the tubes is difficult to be ensured with bending machine. Therefore, the tubes’ 3D geometric error should be fixed according to measurement results. However, there are no convenient methods to accomplish the measurement accurately and effectively. Thus, this paper aims to propose a new tube measurement method to achieve tube's automatic measurement. The accurate measurement results can be used to fix the geometric error of the tube to achieve stress-free assembly. Design/methodology/approach Tubes’ shape can be determined by control points. First, the point clouds of the centre line by multi-stereo-vision technology are reconstructed. Then, the point clouds to the spine of the tube are thinned by moving least-squares and segmented into lines and arcs. Finally, the control points are calculated and the model is reconstructed. The authors can get the tube’s geometric dimensions from the model. Findings The experiment results indicate that the multi-stereo-vision technology can solve the occlusion problem and measure the complicated tubes efficiently and accurately. Originality/value The paper proposed a tube measurement method. The repeatability measuring precision was 0.12 mm, and the absolute measuring precision was within 0.78 mm. The tube spectra assessed in this paper are in the range of angles between two adjacent line segments of 3-177° and the shortest length of the line segment is greater than 5 mm, confirming that the proposed algorithm can measure various complicated tubes effectively and accurately.

scholarly journals A Method of Segmenting Apples Based on Gray-Centered RGB Color Space

2021 ◽  
Vol 13 (6) ◽  
pp. 1211
Author(s):  
Pan Fan ◽  
Guodong Lang ◽  
Bin Yan ◽  
Xiaoyan Lei ◽  
Pengju Guo ◽  
...  
Keyword(s):  
Vision System ◽  
False Positive Rate ◽  
Clustering Algorithms ◽  
False Negative ◽  
Color Space ◽  
False Negative Rate ◽  
Feature Selection Method ◽  
Image Features ◽  
Accurate Identification ◽  
Rgb Color Space

In recent years, many agriculture-related problems have been evaluated with the integration of artificial intelligence techniques and remote sensing systems. The rapid and accurate identification of apple targets in an illuminated and unstructured natural orchard is still a key challenge for the picking robot’s vision system. In this paper, by combining local image features and color information, we propose a pixel patch segmentation method based on gray-centered red–green–blue (RGB) color space to address this issue. Different from the existing methods, this method presents a novel color feature selection method that accounts for the influence of illumination and shadow in apple images. By exploring both color features and local variation in apple images, the proposed method could effectively distinguish the apple fruit pixels from other pixels. Compared with the classical segmentation methods and conventional clustering algorithms as well as the popular deep-learning segmentation algorithms, the proposed method can segment apple images more accurately and effectively. The proposed method was tested on 180 apple images. It offered an average accuracy rate of 99.26%, recall rate of 98.69%, false positive rate of 0.06%, and false negative rate of 1.44%. Experimental results demonstrate the outstanding performance of the proposed method.

Disposition effect at the market level: evidence from Indian stock market

2019 ◽  
Vol 12 (2) ◽  
pp. 69-82
Author(s):  
Sravani Bharandev ◽  
Sapar Narayan Rao
Keyword(s):  
Trading Volume ◽  
Stock Exchange ◽  
Reference Points ◽  
Disposition Effect ◽  
Content Type ◽  
Ex Post ◽  
Abnormal Trading Volume ◽  
The Difference ◽  
Trading Volumes ◽  
Indian Stock Market

Purpose The purpose of this paper is to test the disposition effect at market level and propose an appropriate reference point for testing disposition at market level. Design/methodology/approach This is an empirical study conducted on 500 index stocks of NSE500 (National Stock Exchange). Winning and losing days for each stock are calculated using 52-week high and low prices as reference points. To test disposition effect, abnormal trading volumes of stocks are regressed on their percentage of winning (losing) days. Further using ANOVA, the difference between mean of percentage of winning (losing) days of high abnormal trading volume deciles and low abnormal trading volume deciles is tested. Findings Results show that a stock’s abnormal trading volume is positively influenced by the percentage of winning days whereas percentage of losing days show no such effect. Findings are consistent even after controlling for volatility and liquidity. ANOVA results show the presence of high percentage of winning days in higher deciles of abnormal trading volumes and no such pattern in case of losing days confirms the presence of disposition effect. Further an ex post analysis indicates that disposition prone investors accumulate losses. Originality/value This is the first study, which proposes the use of 52-week high and low prices as reference points to test the market-level disposition effect. Findings of this study enhance the limited literature available on disposition effect in emerging markets by providing evidence from Indian stock markets.

scholarly journals Creating products in the absence of markets: a robust design approach

2008 ◽  
Vol 19 (3) ◽  
pp. 407-420 ◽  
Author(s):  
Philippe Silberzahn ◽  
Christophe Midler
Keyword(s):  
Longitudinal Study ◽  
Product Design ◽  
Robust Design ◽  
Practical Implication ◽  
Collaborative Work ◽  
High Tech ◽  
Content Type ◽  
Exploration Process ◽  
Strategic Process ◽  
Alternative Approach

PurposeThe purpose of this study is to examine how firms deal with a situation of true uncertainty about their potential markets and technologies. Specifically, it asks how firms can create products when the corresponding market does not exist.Design/methodology/approachThis paper is based on a longitudinal study of a high‐tech firm, combined with analysis of existing theory in product design and entrepreneurship.FindingsMarkets and products are usually a defining choice made early on by firms in their strategic process. Such a choice guides their development by providing a “stable concept” to which decisions can be related. When markets do not exist yet, however, this approach is not effective. Early choice of products and markets limits firms' flexibility by constraining their ability and willingness to adapt, while fundamental new technical and market information is likely to emerge during the project that will prove the initial assumptions wrong. The paper shows an alternative approach where products and markets actually result from a generic process of products and markets exploration driven by the firm. It is suggested that this approach forms a robust design in that it allows the firm to deal with the uncertainty by simultaneously developing its products and exploring markets, while preserving the flexibility to adapt to the changing environment.Practical implicationsThe practical implication of this paper is to suggest an alternative approach to deliberate planning in high‐tech ventures. With this approach, rather than markets and products, strategy defines a market and technology exploration process.Originality/valueThe paper is original in three ways. It links the product design and market exploration processes in high‐tech firm development; it is based on an in‐depth longitudinal study; and it results from an academic‐practitioner collaborative work.

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