Efficient measurement procedures for compound part profile by computer vision

It is apparent that automated inspection for manufacturing is on the threshold of broad industrial utilization. One key problem in manufacturing applications of automated inspection is how to find fast and efficient methods using economical computers that industry can afford. Moreover, most mechanical designers set only overall tolerances for part geometric features. In computer vision inspection, as well as in the use of other automated inspection devices and coordinate measuring machines (CMM) the errors of representing each geometric features should be identified separately. The proposed statistical inference method provides a scientific basis for setting inspection tolerances in original geometric space which are compatible with engineering specifications.

The results of this presentation should supply industrial practitioners with an accurate and fast approach for on-line part profile inspection.     

Computer-aided visual inspection for integrated quality control

This paper first briefly introduces the fundamentals of automated inspection techniques, followed by a categorization of typical applications. At its focus the paper elaborates on issues relating to the need for, the approach to and the benefits of integrating automatic inspection systems within the context of computer integrated PCB manufacturing. It argues that automatic inspection systems should assume the role of not only quality inspection systems but also important quality information generators on the shop floor. In particular, integrated quality control will be realized through an integration of inspection systems with process/quality control systems such as statistical process control (SPC).     

Computer vision for quality control in automated manufacturing systems

On-line automated inspection for quality and process control is becoming an important element of automated manufacturing systems. Enabling non-contact, thus non-destructive inspection, optical techniques are especially well suited to industrial inspection needs. In this paper, an image processing system for inspecting round parts is proposed and described. Several measures of out-of-roundness are discussed. Different sampling plants are investigated and the proper sampling plan is suggested.     

Integrity analysis : methods for automating data quality assurance

Data continue to remain a neglected component of electronic data processing (EDP) systems and are largely unsupported by research. As a result, most files contain defective data, and the extent of this condition is not measurable due to a lack of rigorous inspection techniques.

Integrity analysis is a formal methodology for inspecting stored data in a systematic manner, and for quantifying data integrity. Problems in both data and systems are detected by automated data constraints. Result reliability of the inspection processes is ensured by algorithms that provide control and auditability whenever data already identified as defective must proceed through subsequent constraints.

Integrity analysis principles are applicable to quality assurance, EDP audit, systems design, operations, and management, as well as to the design of data dictionaries, database management systems, and generalized software for data inspection.     

一种改进型的S4PR网活性条件

研究了顺序资源共享分配系统的建模模型S4PR (Systems of sequential systems with shared resources)网的活性问题. 已有的研究成果表明, 一个S4PR网在所有信标都满足max, max'或max"-controlled 时能保持活性, 但现有的活性条件对信标的限制严格且不适用于某些网系统, 本文提出了一类名为max*-controlled的改进型条件, 并证明了当一个S4PR网的所有信标都满足max*-controlled条件时, 网系统能保持活性. 与现有的其他条件相比, 新的活性条件更加宽松, 为设计更高允许度的死锁预防或者活性保持监控器提供了理论支撑.     

Automated visual inspection in the semiconductor industry: A survey

Automated visual inspection is an image-processing technique for quality control and production line automation. This paper reviews various optical inspection approaches in the semiconductor industry and categorize the previous literatures by the inspection algorithm and inspected products. The vision-based algorithms that had been adopted in the visual inspection systems include projection methods, filtering-based approaches, learning-based approaches, and hybrid methods. To discuss about the practical applications, the semiconductor industry covers the manufacturing and production of wafer, thin-film transistor liquid crystal displays, and light-emitting diodes. To improve the yield rate and reduce manufacturing costs, the inspection devices are widely installed in the design, layout, fabrication, assembly, and testing processes of production lines. To achieve a high robustness and computational efficiency of automated visual inspection, interdisciplinary knowledge between precision manufacturing and advanced image-processing techniques is required in the novel system design. This paper reviews multiple defect types of various inspected products which can be referenced for further implementations and improvements.     

Database considerations in manufacturing systems integration

This paper deals with ideas that could form a basis for manufacturing integration. In recent times more attention is being paid to the idea of applying artificial intelligence (AI) techniques to manufacturing. However, very little attention is being paid to the proper use of these techniques. This research work explores three basic ideas:

1. 1. Applications of the entity-relationship approach to knowledge representation.

2. 2. The basic philosophy of expert database systems and

3. 3. Integration of manufacturing systems from the above two concepts.

The approaches for 1 and 2 are explained with actual implementation experiences, while a framework for integration is proposed from a more philosophical perspective.     

Design and development of automatic visual inspection system for PCB manufacturing

Inspection of solder joints has been a critical process in the electronic manufacturing industry to reduce manufacturing cost, improve yield, and ensure product quality and reliability. This paper proposes two inspection modules for an automatic solder joint classification system. The “front-end” inspection system includes illumination normalisation, localisation and segmentation. The “back-end” inspection involves the classification of solder joints using the Log-Gabor filter and classifier fusion. Five different levels of solder quality with respect to the amount of solder paste have been defined. The Log-Gabor filter has been demonstrated to achieve high recognition rates and is resistant to misalignment. This proposed system does not need any special illumination system, and the images are acquired by an ordinary digital camera. This system could contribute to the development of automated non-contact, non-destructive and low cost solder joint quality inspection systems.     

A relational graphical editing method for PCB design

PCB design is currently an essential part of the process of manufacturing electronic equipment, and many CAD systems have been developed to facilitate this design process^1,2,3,4. For all these systems the PCB Editor is an important and inevitable component because automatic routers usually have a few simple control strategies for routing². In many cases they cannot produce satisfactory PCB design and existing automatic routing methods cannot guarantee 100% connection in practice, although some of them are successful in theory.     

Contribution of simulation to the optimization of inspection plans for multi-stage manufacturing systems

In this paper we develop a new mathematical model to optimize inspection plans for multi-stage manufacturing systems with possible misclassification errors. The presented model minimizes total inspection related costs while still assuring a required output quality. Because of the complexity of the proposed mathematical model, a simulation algorithm is presented to model the multistage manufacturing system subject to inspection and to estimate the resulting inspection costs. We use the popular Arena simulation software to implement our simulation algorithm and then we utilize OptQuest, Arena’s built-in optimization package, to find the optimal inspection plan. Finally, a numerical example is presented and simulation experiments are also conducted in order to examine the effects of several model parameters.     

Recent advances in the automatic inspection of integrated circuits for pattern defects

Automatic inspection has become an essential part of manufacturing technology for integrated circuit (IC) chips, but three trends in the geometries of ICs and the chips that they comprise have serious implications for inspection, making further advances in technology challenging. The individual devices (e.g., transistors) are becoming smaller, with the smallest features on some advanced products already crossing the optical resolution threshold; the chip areas are becoming larger; and the chips consist of more layers and undergo more processing steps. Not only are the smallest defects more difficult to detect due to the optical resolution limit, they are also much rarer because the tolerable defect density decreases as the chip area increases. This paper addresses automated IC inspection, surveying recent advances and future challenges. An overview of all inspection on IC chips during the manufacturing process is followed by a detailed discussion of pattern defect inspection (PDI) and its unique requirements, such as detection probability, false alarm rate, throughput, and minimum defect size. The core material of the paper consists of a discussion of approaches and systems for PDI, emphasizing recent developments, but reviewing older work to set the proper context. Both work reported in the literature and commercial systems are considered.     

Heuristic knowledge representation of production scheduling: An integrated modeling approach

In spite of the efforts to automate production scheduling systems, most manufacturing plants rely on human schedulers for their practical production scheduling due mainly to the complexity and unpredictability of the manufacturing systems. One of the reasons for the difficulties in automating the production scheduling process is the lack of an explicit representation scheme of heuristic scheduling knowledge.

In this paper, an integrated modeling approach is presented to represent the complicated heuristic knowledge in production scheduling systems. The integrated modeling approach is based on object-oriented and event-driven modeling. It provides the explicit, declarative and executable representation of heuristic scheduling knowledge which aids the communication between human schedulers and system analysts. The declarative and executable representation of scheduling knowledge will enhance the flexibility of production scheduling systems and aid the development of production scheduling information systems.

A heuristic production scheduling model of a tire manufacturing system is used throughout the paper to illustrate the concepts and applicability of the approach.     

Strategies for planning and implementation of flexible fixturing systems in a computer integrated manufacturing environment

In general, for any manufacturing operation to be successful, parts must be located and held to remain in position and orientation when subjected to external forces during the manufacturing operations. The traditional approach to fixturing involves designing and manufacturing special-purpose fixtures. These fixtures are generally dedicated devices designed and manufactured for specific parts and manufacturing operations. Flexible fixturing technology involves employing a single fixturing system to hold workpieces of various shapes and sizes. Such systems have reached the embryonic stage of implementation into manufacturing environment. Therefore the integration of current and future flexible fixturing systems into the manufacturing processes becomes an important issue for future work in computer-integrated manufacturing (CIM) environment.

The approach to CIM is dependent on the functional model of the company. Therefore, the implementation of any sub-systems within it must be studied on an individual basis. However, in order to plan and implement new technologies, such as flexible fixturing systems, within CIM environment, certain requirements must be met and guidelines must be followed. The strategies for planning and implementation of flexible fixturing systems within the larger frame work of CIM environment are presented. Some guidelines for designing and developing the interconnection of the data bases are also discussed.     

The optimal location of inspection stations using a rule-based methodology

The location of inspection stations is a significant component of production systems. In this paper, a prototype expert system is designed for deciding the optimal location of inspection stations. The production system is defined as a single channel of n serial operation stations. The potential inspection station can be located after any of the operation stations. Non-conforming units are generated from a compound binomial distribution with known parameters at any given operation station.

Traditionally Dynamic programming, Zero-one integer programming or Non-linear programming techniques are used to solve this problem. However a problem using these techniques is that the computation time becomes prohibitively large when the number of potential inspection stations are fifteen or more. An expert system has the potential to solve this problem using a rule-based system to determine the near optimal location of inspection stations.

The prototype expert system is divided into a static database, dynamic database and knowledge base. Based on defined production systems, the sophisticated rules are generated by the simulator as part of a knowledge base. A generate-and-test inference mechanism is utilized to search the solution space by applying appropriate symbolic and quantitative rules. The goal of the system is to determine the location of inspection stations while minimizing total cost.     

A knowledge-based system for information management in an automated and integrated manufacturing system

In recent years there has been considerable interest in flexible automation of manufacturing processes in an effort to improve the productivity of manufacturing industry. Central to an integrated, flexible and intelligent manufacturing system is the information management function. The sharing of data is the basis of flexible and intelligent decision-making, the means of integrating the system components, the mode of synchronizing their processes and the method of maintaining the consistency of their states.

It appears that the data management and manipulation function in manufacturing systems is increasingly becoming a bottleneck for further performance improvement of manufacturing systems. New information management systems need to be developed that meet the needs of modern manufacturing systems in terms of efficiency, flexibility, reliability and intelligence. A new model for an integrated manufacturing information system is presented. A double structure of two parallel but independent system is proposed for manufacturing control and manufacturing information management. The objective is to improve service efficiency. representational adequacy, consistency of information and reliability in the information system.     

Automatic inspection for phase-shift reflection defects in aluminum web production

Industrial inspection problems usually require specific and highly complex solutions that can be implemented at a reasonable cost, what has produced a great research and development effort in the field of computer vision. Among these problems, inspection systems for continuous feed production (named as web-inspection), are those that raise the main challenges for the researchers exceeding the current systems capacity. Manual inspection, that is still being used in many cases, does not allow to reach detection guarantees, accuracy, robustness and a high volume that are required in web-based manufacturing.     

Markerless cooperative augmented reality-based smart manufacturing double-check system: Case of safe PCBA inspection following automatic optical inspection

Augmented reality (AR) is a key technology anchored towards realizing Industry 4.0 smart manufacturing aims. In manufacturing inspection, AR has previously been employed to support operators in assessing thickness of manufactured parts, ship building, aircraft subassemblies and printed circuit board assemblies (PCBAs) with or without external markers in standalone head-mounted (HMD) or handheld systems. These AR systems often use optical see-through (OST) or video see-through (VST) technologies. Currently, cyber physical integration of processes in an industrial system synergizes production through increased efficiency and improved quality while facilitating customization. An operator manually double-checking/inspecting a product that has previously been automatically inspected can better rely on this existing defect location information once it is contextually and spatially overlaid within their field of view to intuitively and efficiently execute the task. Additional interactive information provided can quickly reorient a user, provide necessary contextual reference, and monitor progress of the task while alerting them of their safety. In this study, adopting an automatic optical inspection (AOI) wirelessly aided HMD-OST AR-based manual inspection system requiring no external markers for contextual registration is a promising direction towards smart and safe PCBA manufacturing in line with Industry 4.0. Animated rectangular bracket of high color contrast is employed to localize the spawned AOI defect point, an arrow overlaid with distance text provides user guidance, a contextual resizable image facilitates user double-checking and a progress bar tracks the inspection progress while monitoring tracking state. We evaluate the developed system's robustness, effectiveness of display technology used, suitability of contextual against static display modes, and display technology influence on various inspection attributes in a user study. Results demonstrate the system to be robust, OST-HMD outperforms handheld VST devices, contextual display mode to be significantly preferred to static mode, and display technology employed has no significant influence on the inspection attributes. Finally, registration precision results demonstrate usability of the system while superposition of distance to orientation information raises the inspection rate of PCBAs.     

Evaluation of a job‐aiding tool in inspection systems

Visual inspection plays a very important role in ensuring quality in the manufacturing and service industries. Two determinants of inspection performance are visual search and decision‐making. Improvement in any one of the components will have an impact on system performance. Job‐aids, accompanied by training, have proven to be effective in enhancing accuracy and reducing search time in visual inspection systems. This article aims to investigate the effects of search strategy along with task complexity and pacing on inspection performance using a job‐aiding tool. To facilitate the experiments, an enhanced job‐aiding tool in a simulated visual inspection environment was developed. This tool enables an inspector to track his or her search path in visual inspection systems. A pilot study and two experiments were conducted using this tool. The pilot study examined the effectiveness of the job‐aiding tool. The first experiment studied the effect of search strategy and task complexity on inspection system performance and the second experiment studied the impact of search strategy, task complexity, and pacing on system performance. Results from this research can be used to better design an inspection system. © 2007 Wiley Periodicals, Inc.     

Automated Refinement of Automated Visual Inspection Algorithms

One of the challenges faced by the users of automated visual inspection (AVI) systems is how to efficiently upgrade the legacy systems to inspect the new components introduced into the assembly lines. If the AVI systems are not flexible enough to accommodate new components, they will be rendered obsolete even by small changes in the product being inspected. The overall objective of the research presented in this paper is to produce the methodological basis that will result in the development of highly reconfigurable AVI systems. In this paper, we focus on part of this overall development, the adaptation of preexisting inspection algorithms to inspect similar components introduced into the assembly line. While this paper bases its development and discussion on the inspection of surface mounted devices (SMDs), the proposed methodology is general enough to be applicable to a broad range of inspection problems.