Search

Several continuous manufacturing processes use stochastic texture images for quality control and monitoring. Large amounts of pictorial data are acquired, providing important information about both the materials produced and the manufacturing processes involved. However, it is often difficult to measure objectively the similarity among industrial stochastic images or to discriminate between texture images of stochastic materials with distinct properties. Nowadays, the degree of discrimination required by industrial processes often goes beyond the limits of human visual perception. This paper proposes to model this specific class of textures as colored noise and presents a new approach for multiresolution stochastic texture representation and discrimination in industry (e.g., nonwoven textiles and paper). The wavelet transform is used to represent stochastic texture images in multiple resolutions and to describe them using local orientation and density variability as features. Based on this representation, a multiresolution distance measure for stochastic textures is proposed, and industrial applications of the method and experimental results are reported. The conclusions include ideas for future work. [ABSTRACT FROM AUTHOR]

High-mix-low-volume (HMLV) production is currently a worldwide manufacturing trend. It requires a high degree of customization in the manufacturing process to produce a wide range of products in low quantity in order to meet customers' demand for more variety and choices of products. Such a kind of business environment has increased the conversion time and decreased the production efficiency due to frequent production changeover. In this paper, a layered-encoding cascade optimization (LECO) approach is proposed to develop an HMLV product-mix optimizer that exhibits the benefits of low conversion time, high productivity, and high equipment efficiency. Specifically, the genetic algorithm (GA) and particle swarm optimization (PSO) techniques are employed as optimizers for different decision layers in different LECO models. Each GA and PSO optimizer is studied and compared. A number of hypothetical and real data sets from a manufacturing plant are used to evaluate the performance of the proposed GA and PSO optimizers. The results indicate that, with a proper selection of the GA and PSO optimizers, the LECO approach is able to generate high-quality product-mix plans to meet the production demands in HMLV manufacturing environments. [ABSTRACT FROM AUTHOR]

Current production leanings, such as high product variability, demand advanced manufacturing systems (MSs). An example is the holonic MS (HMS) in which entities (e.g., resources and products) are "smart." These entities are called holons (HLs), and their interactions are coordinated by holonic control (HC). Indeed, the complexity of HMS has required new design and test tools. In this context, this paper presents an HC metamodel, which was applied to a particular simulator. In this control solution, causal knowledge is enclosed in Rule HLs, which receive facts about Resource HLs and deliberate about the actions to be executed. The inference happens by means of an innovative net of notifications built from expert knowledge, in the form of (Sub)-HLs, which allows high reactivity, HL decoupling, conflict handling, coherent control expression and execution, and easy control adaptations. This solution still considers other issues, namely, the product-driven manufacturing: a tendency related to customized production in which Product HLs negotiate with Resource HLs aiming at adaptability and reactivity. In this case, Rule HLs intermediate and organize the collaborations of Product HLs and Resource HLs. This paper proposes to use the metamodel to compose a process-driven control and a product-driven control applied to a similar simulated HMS, highlighting their differences and advantages. [ABSTRACT FROM AUTHOR]

Product development in modern enterprises usually involves collaboration among designers, suppliers, contract manufacturers to achieve efficiency and rapid response to changing markets. Product-development cost, lead time, and reliability are very critical elements in addition to functional features. However, it becomes increasingly challenging to obtain an optimal decision with respect to these multiple criteria as the number of involved entities increases in modern product developments. There is a clear need for planning tools to support effective decision making in this domain. The availability of efficient and accurate multiobjective optimization (MOO) algorithms becomes critical in such a decision support tool. This paper poses the product development as a multiobjective assignment problem in the context of printed circuit board assembly (PCBA) industry. We describe a new class of MOO algorithm based on the principles of differential evolution (DE). The multiobjective DE (MODE) algorithm is shown to approach Pareto-optimal solutions in a wide class of problems with better performance than the nondominated sorting genetic algorithm II from the literature, providing a practical tool for product-development decision support. A decision support system based on the object-oriented design methodology is described in this paper with the MODE as the core search engine. Experimental study of this decision support system is conducted using two real-world PCBA designs. We demonstrate the effectiveness of this proposed MODE algorithm and some use cases of such decision support system on facilitating decision makers' tradeoff analysis. [ABSTRACT FROM AUTHOR]

Tool path planning for automated manufacturing processes is a computationally complex task. This paper addresses the problem of tool path integration in the context of spray-forming processes. Tool paths for geometry-complicated parts are generated by partitioning them into individual freeform surfaces, generating the paths for each partition, and then, finally, interconnecting the paths from the different patches so as to minimize the overall path length. We model the problem as a variant of the rural postman problem (RPP), which we call open-RPP. In this paper, we present two different solutions to the open-RPP. The first solution is based on genetic algorithms and the second one is based on ant colony optimization. This paper presents and compares the results from both methods on sample data and on real-world automotive body parts. We conclude this paper with remarks about the effectiveness of our implementations and the pros and cons of each method. [ABSTRACT FROM AUTHOR]

A significant effort in recent computer-integrated manufacturing (CIM) development was carried out by SEMATECH who had laid out and created an open framework for the integration of manufacturing execution system applications running in semiconductor industries at the factory operation level. This paper presents the feasibility to incorporate basic manufacturing applications at the factory engineering level, which include product design, process planning, and material requirement planning, into the SEMATECH CIM framework to form a generic framework across both factory operation level and factory engineering level. The CIM framework established in this paper was aimed to provide a reusable integrated system framework that clearly specifies the functional interface boundaries and standard information model of the required components, in general, manufacturing systems at both factory operation and factory engineering levels. Standard unified modeling language (UML) diagrams and Petri nets have been utilized to model and analyze the specifications and dynamic behaviors of this generic CIM framework. The goal is to build a framework by creating a common, modular, flexible, and integrated object model that unifies an advanced object-oriented architecture concept and heterogeneous manufacturing application development in an open and multisupplier CIM system environment. [ABSTRACT FROM AUTHOR]

This paper proposes a new Petri net class, namely, Ratio-enforced weighted Augmented Marked Graphs (RAMGs), and solves ratio control and liveness-enforcing supervision problems for automated manufacturing systems. RAMGs can ensure the required product ratios as demanded by production planners. Since the deadlock of such a system can be attributed to improper acquisition of finite shared resources, a supervisor is introduced such that they are properly allocated. This paper proves that ratio and supervisory controllers for an RAMG can be separately designed. Their design methods are presented. Examples are given to illustrate them. [ABSTRACT FROM AUTHOR]

This paper proposes a time-computing model and a scheduling method for shortening the completion time of product development under the given rework cost budget. As overlapping and iteration exist between or among design activities in concurrent product development, predictability and efficiency of the process deserve attention. By using the corresponding design structure matrix, the characteristics of information flow are obtained and applied to analysis of the dynamic behavior of the product development process. A time-computing model is set up to estimate the rework cost and completion time of each of the activities, between which both iteration and overlapping are observed. Through sequential quadratic programming, an optimization algorithm is developed for minimizing the development completion time under the constraint of the given rework cost budget. Our application results acquired from our experiments have verified the feasibility and validity of the approach. [ABSTRACT FROM AUTHOR]

Testing complex manufacturing systems, such as an ASML lithographic machine, takes up to 45% of the total development time of a system. The problem of which tests must be executed in what sequence to ensure in the shortest possible test time that the system works, which is the test-sequencing problem, was already solved by Pattipati et al. for the diagnosis of systems during operation. Test-sequencing problems during the development and manufacturing phases of systems, however, require a different approach than the test-sequencing problems during operation. In this paper, the test problem description and algorithms developed by Pattipati et a!. are extended to solve test-sequencing problems for the development and manufacturing of manufacturing systems. For a case study in the manufacturing process of an ASML lithographic machine, it is shown that solving a test-sequencing problem with this method can reduce the test time by 15% to 30% compared to experts that solve this problem manually. [ABSTRACT FROM AUTHOR]

This paper reports on the progress made toward the emergence of standards to support the integration of heterogeneous discrete-event simulations (DESs) created in specialist support tools called commercial-off-the-shelf (COTS) discrete-event simulation packages (CS Ps). The general standard for heterogeneous integration in this area has been developed from research in distributed simulation and is the IEEE 1516 standard The High Level Architecture (HLA). However, the specific needs of heterogeneous CSP integration require that the HLA is augmented by additional complementary standards. These are the suite of CSP interoperability (CSPI) standards being developed under the Simulation Interoperability Standards Organization (SISO-http://www.sisostds.org) by the CSPI Product Development Group (CSPI-PDG). The suite consists of several interoperability reference models (IRMs) that outline different integration needs of CSPI, interoperability frameworks (IFs) that define the HLA-based solution to each IRM, appropriate data exchange representations to specify the data exchanged in an IF, and benchmarks termed CSP emulators (CSPEs). This paper contributes to the development of the Type I IF that is intended to represent the HLA-based solution to the problem outlined by the hype I IRM (asynchronous entity passing) by developing the entity transfer specification (ETS) data exchange representation. The use of the ETS in an illustrative case study implemented using a prototype CSPE is shown. This case study also allows us to highlight the importance of event granularity and lookahead in the performance and development of the Type I IF, and to discuss possible methods to automate the capture of appropriate values of lookahead. [ABSTRACT FROM AUTHOR]

This paper is about fault detection and identification of discrete event systems. The proposed approach is based on Petri nets (PNs) that are used to design reference and faulty models. The main contribution concerns the design and identification of these models according to the statistical analysis of the alarm sequences that are collected on the considered system. The model structure is described as a state graph, and the parameters of the probability density functions (pdfs) for transition firing periods are estimated. Normal and exponential pdfs are considered, and estimation is detailed in case of concurring behaviors. The reference models, described as timed PNs, are then used for fault detection and isolation issues. Finally, stochastic PNs with normal and exponential pdfs are considered to include a representation of the faulty behaviors. [ABSTRACT FROM AUTHOR]

Reactive ion etching (RIE) is a process in the fabrication of semiconductor devices. The ability to predict the influence of the process parameters of RIE is crucial in terms of machine performance as they may have a serious impact on product quality as well as on the probability of machine failure. To address this issue, this correspondence paper presents a novel performance tradeoff function for evaluating the overall suitability of adopting the predicted control parameters suggested by domain experts, taking into full consideration their impact on the performance of the machine involved. An experiment using the RIE machine is provided to validate the practicability of the proposed approach. [ABSTRACT FROM AUTHOR]

In the procedure of steady-state hierarchical optimization with feedback for a large-scale industrial process, it is usual that a sequence of step set-point changes is carried out and used by the decision-making units while searching the eventual optimum. In this case, the real process experiences a form of disturbances around its operating set-point. In order to improve the dynamic performance of transient responses for such a large-scale system driven by the set-point changes, an open-loop proportional integral derivative-type iterative learning control (ILC) strategy is explored in this paper by considering the different magnitudes of the controller's step set-point change sequence. Utilizing the Hausdorff-Young inequality of convolution integral, the convergence of the algorithm is derived in the sense of Lebesgue-P norm. Furthermore, the extended higher order ILC rule is developed, and the convergence is analyzed. Simulation results illustrate that the proposed ILC strategies can remarkably improve the dynamic performance such as decreasing the overshoot, accelerating the transient response, shortening the settling time, etc. [ABSTRACT FROM AUTHOR]

To achieve an effective integration framework for manufacturing systems, a formal model of a system is highly desired. In spite of significant work on automated manufacturing systems, human operators still play a critical role in virtually every system, especially for material-handling processes. To build a model for control and analysis of a system where a human operator is integrated, a formal functional specification of a human material handler (MH) is presented in a hierarchical framework. Two types of human operational errors associated with material. handling tasks are also classified and discussed. A shop floor control example is provided to illustrate the proposed modeling framework. [ABSTRACT FROM AUTHOR]

Process manufacturing is increasingly being driven by market forces, customer needs, and perceptions, resulting in more and more complex multiproduct manufacturing technologies. The increasing automation and tighter quality constraints related to these processes make the operator's job more and more difficult. This makes decision support systems (DSSs) for the operator more important than ever before. A traditional operator support system (OSS) focuses only on specific tasks that are performed. In the case of complex processes, the design of an integrated information system is extremely important. The proposed data-warehouse-based OSS makes possible linking complex and isolated production units based on the integration of the heterogenous information collected from the production units of a complex production process. The developed OSS is based on a data warehouse designed by following the proposed focus-on-process data-warehouse-design approach, which means stronger focus on the material and information flow through the entire enterprise. The resulting OSS follows the process through the organization instead of focusing separate tasks of the isolated process units. For human-computer interaction, front-end tools have been worked out, where exploratory data analysis and advanced multivariate statistical models are applied to extract the most informative features of the operation of the technology. The concept is illustrated by an industrial case study, where the OSS is designed for the monitoring and control of a high-density polyethylene (HDPE) plant. [ABSTRACT FROM AUTHOR]

Analyzes the class of Petric nets constructed by a modular approach for modeling manufacturing systems with shared resources, using siphons. Basic notion of nets; Resource control net-merged nets; Properties; Siphons, circular structure and circular-wait; Example.

Discusses the implementation of forward kinematic equations of position of robotics manipulators, using a distributed arithmetic-based pipeline architecture. Use of distributed arithmetic-based circuits that implement the matrix vector multiplications involved in the calculation of forward kinematics position; Digit-serial configuration of the proposed implementation.

Describes the efficient walking pattern for a practical biped robot when ascending and descending stairs. Main features of the biped robots, which include variable length legs and a translatable balance weight in the body; Need to ensure that biped robot's walk is statically stable and dynamically stable; Advantages provided by the biped robot's large feet.