视野培训对视觉搜索绩效的影响

视觉搜索在质检、安检等领域有着广泛应用。本研究应用2（培训强度：高,低）×2（反馈：有,无）组间实验进行了视野培训对视觉搜索绩效的影响的研究。结果表明,高强度或有反馈的视野培训能够增大视野面积,改善视野形状,从而显著提高视觉搜索绩效。高强度的培训对视觉搜索绩效的改善幅度显著大于低强度培训。培训强度与反馈对视觉搜索绩效的影响有交互作用,高强度有反馈的视野培训对视觉搜索绩效改善幅度最大。     

不同年龄段人群的动态有效视野研究

探究年龄对动态有效视野特征变化的影响。采用动态视觉搜索任务,共测试样本138人。研究结果表明,年龄对动态有效视野特性具有显著影响,随着年龄增加,有效视野面积、有效视野周长和形状因子随之下降;视野特性受凝视点移动速度影响,随着速度增加,视野范围有缩小且视野形状偏离圆形的趋势。本文的研究可为针对不同年龄段人群设计动态视觉搜索任务提供指导。     

Visual facility layout design system

This paper presents an integrated visual facility layout design system to solve layout problems with geometric constraints on a continual planar site. The system employs a tabu search algorithm as the search engine with heuristic neighbourhood control and a manual interference mechanism to obtain good solutions. The Windows®-based system provides layout designers with a friendly environment that can automatically search a good solution aided by the visual inspection function. The visual inspection function is a mechanism embedded in the search process that dynamically displays the improvement status and allows manual adjustment of facility location during the search. The system also serves as a powerful tool for performing 'what if' analyses for layout designers.     

Optimum speed of visual inspection using a systematic search strategy

In an earlier paper, the authors presented models of human functioning in visual inspection and derived optimal working speeds to balance the cost of time and the cost of errors. Both self-paced and externally paced models assumed a random search strategy. It was noted that choosing a standard speed for visual inspection is difficult with standard work measurement techniques and that the data required for the suggested search model are easily measurable. The purpose of this paper is to complement the earlier work by deriving similar models employing a systematic search strategy. The two models can be considered as bounds on actual performance; thus the current paper complements the previous one by establishing an upper bound rather than a lower bound on performance in search tasks. Comparisons between the two strategies are presented.     

矿山瓦斯监控界面多目标视觉告警编码形式研究

目的 探究矿山瓦斯监控界面多个目标同时告警时的最优视觉告警编码形式。方法 以矿山瓦斯监控系统为研究背景,选取颜色、大小、字符三种视觉编码形式对注意、警告、危险三种告警等级进行单目标和双目标的视觉搜索实验。结果 通过对正确率、反应时间以及主观评分的分析发现,无论是单目标还是双目标视觉搜索实验,当界面视觉告警形式采用颜色编码时,搜索绩效最优;相比于采用字符编码,采用大小编码时的搜索时间更短,但其正确率却稍低。实验结果还发现在双目标视觉搜索实验中,告警等级的异同对反应时间具有显著性影响,告警等级相同的比告警等级不同的两目标搜索时间更短,且搜索过程中第二个目标比第一个目标更容易被发现。结论 研究结果对于提高矿山瓦斯监控系统界面的安全性,减少监控人员的认知决策失误具有重要意义,同时也对其他监控界面中多目标视觉告警形式的设计具有一定的指导价值。     

THE OPTIMUM SPEED OF VISUAL INSPECTION USING A RANDOM SEARCH STRATEGY

Choosing a standard speed for visual inspection is difficult using standard work measurement techniques. This paper uses a different approach, taking a model of human functioning in inspection and deriving an optimum speed of working so as to balance the cost of time against the cost of errors. Random search is used as the model and both self-paced and externally-paced conditions are derived for multiple fault types. Optimization using a Golden Section search is used to provide optimum inspection speed.     

Automatic recognition of welding defects in real-time radiography

This paper describes a real-time radiography configuration for the automatic inspection of welds. The optimal geometrical imaging configuration is evaluated and discussed in relation to conventional film radiography. For the automatic inspection of X-ray images, a two-step analysis was adopted: a fast search for defective regions, followed by fine identification and location of defects. Two different algorithms, based on the relative irregular behaviour of a defect, were developed for the fast search procedure. The second step, fine identification, can be achieved by a sequential similarity detection algorithm or by a thresholding algorithm. The different methods were applied to various X-ray images of welds and the automatic inspection was evaluated and compared with visual inspection.     

A theory of structured visual search and target luminance,with applications to some industrial inspection tasks

The importance of target luminance in evaluating tho relative efficiency of structured versus unstructured search in a large and visually homogeneous field is discussed.

Differences in detection times appear to be due to the apparent luminance of the target. Detection is a result of a trade-off between the physical luminance of the target and the degree of spatial uncertainty associated with a particular search pattern. In a structured visual field, with a systematic search pattern, the spatial uncertainty of the target is conceived as being lower than with an unstructured field and search pattern.

Evidence from studies on visual search and on the effect of spatial uncertainty on visual performance are presented. Some of the industrial implications of the theory, particularly in the field of inspection, are also described.     

Validating the random search model for a double-target search task

A random visual search model was fit to 2980 search times obtained from a double-target search task. The overall adequacy and prediction accuracy of the model for various search time parameters like mean and median search times, and response times for both individual and pooled data show that subjects' search strategy may reasonably be inferred from search time distributions. The results also suggest the general applicability of the random search model for describing the search behaviour of a large number of subjects performing the type of search task used here, and the practical feasibility of its application for determination of stopping policy in optimization of inspection system design. Notwithstanding the general conformity of the data with the model, some extremely long search times were found, and this was accounted for by the characteristics of visual lobes, nonoptimum interfixation distances and inappropriate overlapping of lobes previously reported. An interpretation of temporal changes of subjects' search strategies during target detection was made by considering the cross-over phenomenon exhibited by the two cumulative detection percentage curves.     

Visual inspection of components for mechanized assembly

Analyses (Boothroyd and Redford 1968) have indicated that a knowledge of the relationship between parts quality and cost is essential if the performance of a mechanized assembly machine is to be optimized. For mass-production parts, improvements in parts quality are invariably obtained by some form of inspection and a knowledge of the cost of and efficiency of inspection is therefore desirable.

Experiments have been carried out for visual inspection to determine the effect on inspection rate and efficiency of changing the quality of the part being inspected and the number, position and type of features of the part which can be inspected. The results of this work are presented in this paper and their significance is discussed.     

Sequencing of imperfect inspection operations subject to constraints on the quality of accepted and rejected units

Several imperfect inspection operations are available in a discrete production environment. A decision regarding acceptance or rejection of the produced items needs to be made without exceeding specified limits for the probabilities of accepted units being non-conforming and rejected units conforming to quality specifications. A branch and bound approach is used to find the inspection sequence resulting in least expected total inspection cost. Following the heuristic construction of a trial solution, a dominance relationship is applied to search the tree of possible sequences for the optimal sequence. A numerical example is included.     

复合材料结构冲击损伤检出概率的试验研究与分析

复合材料结构在服役过程中遇到的损伤主要来自于意外冲击, 会产生永久性的凹坑。为了得到凹坑的检出概率, 采用最大似然估算法对一般目视检测(GVI)和详细目视检测(DET)的两种损伤检出概率模型(POD评估模型, 即累积对数正态模型和对数奇函数模型)中的参数进行评估; 开展详细目视检测的试验研究, 并根据检测数据对POD模型进行了验证。结果表明: 凹坑深度的检出概率曲线更符合累积对数正态模型。绿色板的凹坑比黑色板更容易被检出, 且检测角越大越容易被检出。目视勉强可见损伤(BVID)的门槛值在0.35~0.8 mm之间。     

Driving performance of the elderly

While driving on a freeway, visual search patterns, vehicle velocity and voluntary visual occlusion times were recorded for a group of aged and a group of young drivers. The 13 aged drivers were between 60 and 70 years of age; the young drivers were between 21 and 29. In the laboratory all subjects were given a visual search test, an embedded figures test and a motor test. Differences in aged and young performance were found both in freeway driving and the laboratory tests. The results indicate that countermeasures need to be developed in order to aid older drivers.     

LED Lighting Configurations for Visual Inspection of IC Packages

This article discusses configurations of light-emitting diode (LED) light sources for visual inspection of integrated circuit (IC) packages. A package visual inspection (PVI) system with multiple LED light sources used for inspection of IC packages was designed. The image contrast changes of the sample IC packages are explained using the Torrance-Sparrow (TS) model. A few conclusions on appropriate lighting configurations for inspection of various IC packages are achieved. The TS model can be used to represent the specular lobe component. The contrast between two surfaces with different surface roughness values increases with increasing θ_i (incident light angle). Lighting C (θ_i = 75°) is recommended for packages with high surface roughness heights and resin materials. Lighting B (θ_i = 60°) is recommended for packages with moderate surface roughness heights and metal materials. If the background is white, the use of light sources A (θ_i = 15°) and B simultaneously is recommended. Light sources A and C are recommended to be chosen for packages with low surface roughness values and transparent materials. The experimental results with the actual gray-level values of the images are compared to support the conclusions. The PVI system is part of an inspection machine. All images of the sample IC packages reported in this article were obtained from an actual production line. Therefore, the results are close to those of the actual inspection situation in the manufacturing industry.     

Older drivers and rapid deceleration events: Salisbury Eye Evaluation Driving Study

Drivers who rapidly change speed while driving may be more at risk for a crash. We sought to determine the relationship of demographic, vision, and cognitive variables with episodes of rapid decelerations during five days of normal driving in a cohort of older drivers. In the Salisbury Eye Evaluation Driving Study, 1425 older drivers aged 67–87 were recruited from the Maryland Motor Vehicle Administration's rolls for licensees in Salisbury, Maryland. Participants had several measures of vision tested: visual acuity, contrast sensitivity, visual fields, and the attentional visual field. Participants were also tested for various domains of cognitive function including executive function, attention, psychomotor speed, and visual search. A custom created driving monitoring system (DMS) was used to capture rapid deceleration events (RDEs), defined as at least 350 milli-g deceleration, during a five day period of monitoring. The rate of RDE per mile driven was modeled using a negative binomial regression model with an offset of the logarithm of the number of miles driven. We found that 30% of older drivers had one or more RDE during a five day period, and of those, about 1/3 had four or more. The rate of RDE per mile driven was highest for those drivers driving <59 miles during the 5-day period of monitoring. However, older drivers with RDE's were more likely to have better scores in cognitive tests of psychomotor speed and visual search, and have faster brake reaction time. Further, greater average speed and maximum speed per driving segment was protective against RDE events. In conclusion, contrary to our hypothesis, older drivers who perform rapid decelerations tend to be more “fit”, with better measures of vision and cognition compared to those who do not have events of rapid deceleration.     

Extension of the visual search models of inspection

Human performance in a visual search task is generally measured by a cumulative probability distribution of locating a target in a given time period. In this paper, this cumulative probability function has been derived for two systematic search strategies, non-overlapping and overlapping; with both infinitesimal and finite defect length. Moreover, for the infinitesimal defect size case, economic models are derived under the assumption that the number of defects on the search line follows a one-dimensional Spatial Poisson distribution to determine the best inspection stopping time. This research first extends the typical infinitesimal defect size assumption to a finite defect length assumption. Then, it extends the single infinitesimal defect case to the case of random number of infinitesimal defects and develops economic models for two extreme systematic search strategies.     

Visual Inspection of Highway Bridges

The Federal Highway Administration recently conducted an investigation to assess the reliability of visual inspection of highway bridges as implemented by state departments of transportation. The study focused on routine and in-depth inspection, the two most prevalent forms of visual inspection of bridges. Because visual inspection is a highly subjective nondestructive evaluation technique, the results of these bridge inspections can be highly variable and are dependent on many factors. This study included the completion of 10 bridge inspection tasks by 49 practicing state bridge inspectors. With regard to routine inspections, this study showed that condition ratings are assigned with significant variability. Specifically, approximately 68% of condition ratings are within 1 rating point of the average. The results of the in-depth superstructure inspections indicated that these inspections are not likely to detect and identify the specific types of defects for which this inspection procedure is sometimes prescribed. Specifically, widespread defects such as those normally noted during a routine inspection are likely to be noted; however, local deficiencies, such as crack indications, are unlikely to be detected. The results of the deck delamination survey indicate that the accuracy of this type of inspection is relatively poor, with few inspection teams providing results that could be considered to accurately portray the condition of the deck.     

VISUAL INSPECTION STRATEGY

Considerable attention has already been devoted to the many aspects of the inspection task and findings suggest that the factors affecting the efficiency of inspection are subtle and not easily controlled. However, observation of the visual inspection techniques used in most factories suggests that this is not generally recognised and that there is an entirely misplaced confidence in the effectiveness of 100% visual inspection

In this study, consideration is given to some of the factors affecting visual inspection, and trials have been made, which, whilst showing inspection decisions to be inconsistent, suggest ways of achieving a progressive improvement. It is recognised, however, that variability is inevitable in the making of subjective judgements.     

Three-color mixing for classifying agricultural products for safety and quality

A three-color mixing application for food safety inspection is presented. It is shown that the chromaticness of the visual signal resulting from the three-color mixing achieved through our device is directly related to the three-band ratio of light intensity at three selected wavebands. An optical visual device using three-color mixing to implement the three-band ratio criterion is presented. Inspection through human vision assisted by an optical device that implements the three-band ratio criterion would offer flexibility and significant cost savings as compared to inspection with a multispectral machine vision system that implements the same criterion. Example applications of this optical three-color mixing technique are given for the inspection of chicken carcasses with various diseases and for apples with fecal contamination. With proper selection of the three narrow wavebands, discrimination by chromaticness that has a direct relation with the three-band ratio can work very well. In particular, compared with the previously presented two-color mixing application, the conditions of chicken carcasses were more easily identified using the three-color mixing application. The novel three-color mixing technique for visual inspection can be implemented on visual devices for a variety of applications, ranging from target detection to food safety inspection.     

Ruggedness Study of HPLC Peptide Mapping for the Identity of a Drug Compound: A Chemometrics Approach

A statistically more reliable approach than the traditional visual inspection of peptide maps to identify a drug compound is to generate a set of reference standards from a designed experiment that incorporates many possible factors that affect variation of peptide mapping. In fact, the experiment can be done for a ruggedness study as part of a high-performance liquid chromatography (HPLC) method validation. Once the ruggedness is proved with the study, those articles in the experiment may form a set of reference standards, and future articles can be compared to the set later to prove identity. A quantitative analysis of the ruggedness study can be done using a chemometrics approach, principal component analysis (PCA). The analysis is used to reduce the many channels of peptide maps to a few manageable dimensions. The scores projected onto the reduced dimensions are used to test factor effects of the ruggedness study. As a by-product, the analysis provides visual inspection of the set of articles in the experiment for any outliers and anomalies.