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Emerging Technologies and Factory Automation, 1995. ETFA '95, Proceedings., 1995 INRIA/IEEE Symposium on

Date 10-13 Oct. 1995

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  • Proceedings 1995 INRIA/IEEE Symposium on Emerging Technologies and Factory Automation. ETFA'95

    Publication Year: 1995
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  • Analyzing system reliability using non-regenerative stochastic Petri nets

    Publication Year: 1995 , Page(s): 399 - 406 vol.3
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    We extend the class of Markov models that can be described by a stochastic Petri net and describe analytical techniques for solving the resulting model. We consider a generalization of the Markov renewal process in which some of the states may not constitute regeneration points. We present a non-regenerative stochastic Petri net (NRSPN) that generates such a process, discuss its solution, and present an example of a spare-parts inventory system using the NRSPN model. After reviewing SPNs and Markov renewal processes, we define the NRSPN model in the context of a generalized Markov renewal process. Numerical results for specific distributions are given View full abstract»

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  • A discrete time model of a car assembly system

    Publication Year: 1995 , Page(s): 537 - 547 vol.3
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    The performance evaluation of assembly lines under stochastic influence (changing model mix and varying processing times) is usually done by time consuming simulation experiments, In this paper a discrete time queueing model is presented that is a basis of an approximate performance analysis of car assembly systems. The model elements are described and approximate calculation methods for the waiting time and interdeparture time distributions at each work station are derived View full abstract»

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  • On the optimization of a single-stage generalized kanban control system in manufacturing

    Publication Year: 1995 , Page(s): 437 - 444 vol.3
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    We consider a manufacturing system that uses a pull control mechanism to determine when to release raw parts at its input based on actual customer demands for finished parts at its output. This pull control mechanism depends on two parameters: the number of kanbans, which are cards authorizing the release of raw parts into the system, and the base stock of finished parts. We call this system the single-stage generalized kanban control system (GKCS). The conventional single-stage KCS is a special case of the single-stage GKCS in which the base stock of finished parts is equal to the number of kanbans. The single-stage KCS therefore depends on only one parameter. In this paper it is shown that the computational complexity of optimizing the single-stage GKCS is the same as that of optimizing the single-stage KCS even though the former system depends on two parameters, whereas the latter system depends on only one parameter View full abstract»

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  • An anti-blocking control policy for tandem queueing networks

    Publication Year: 1995 , Page(s): 549 - 556 vol.3
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    Blocking phenomena may appear in any queueing network with limited capacity queues. We propose a simple admission control policy, to decrease the risks of blocking which deteriorate the system performance. Under classical Markov assumptions, the controlled system is exactly modelled in the case of two tandem queues, and approximately modelled for more than two queues. The quality of the approximate analytical model is then assessed by comparison with simulation results. It is established that in most cases, the performance of the controlled system is much higher than that of the uncontrolled system View full abstract»

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  • Analysis of proportional machine allocation scheme in a deterministic reentrant line

    Publication Year: 1995 , Page(s): 185 - 193 vol.3
    Cited by:  Papers (1)
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    This paper analyzes the properties of a proportional machine allocation scheme in a reentrant production line of one product and one machine group. The scheme allocates machines to each production stage proportional to the workload of the stage. It is proved that given initial work-in-process (WIP) distribution and a constant work release rate in the capacity of the line, there exists a unique, full machine capacity allocation for the line; when the proportional machine allocation scheme is repetitively applied over time, the whole reentrant line is eventually balanced. These results obtained under such a simplified scenario also provide some insights to the dynamics and resource allocation problem of a reentrant line View full abstract»

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  • Actuation in microsystems: problem field overview and practical example of the piezoelectric robot for handling of microobjects

    Publication Year: 1995 , Page(s): 21 - 27 vol.3
    Cited by:  Papers (7)
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    Microsystems, and in particular microrobots, require the development of new advanced actuators with very small dimensions, simple mechanical construction and high reliability. This paper presents an overview on the problem field of the microactuation and various kinds of actuation principles referring to the use of microrobots. To provide a microrobot with both the transportation and micromanipulation capabilities, various designs of piezoelectric actuators can be used. The piezoelectric robot for handling of microobjects (PROHAM) is proposed. The robot is equipped with three piezoelectrically driven legs, whereby it can move at a speed of several mm/sec. A manipulation tool, e.g. needle, pipette, gripper or glue applicator, can be mounted onto the robot's platform. The tool is driven by piezoelectric effect as well, and movements with an accuracy of 10 nm are possible. This allows the manipulation of very small objects under a microscope. The PROHAM can be used e.g. for the manipulation of biological cells, microassembly or testing of silicon chips View full abstract»

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  • Results of the worst-case analysis for some scheduling problem

    Publication Year: 1995 , Page(s): 105 - 115 vol.3
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    The paper deals with the permutation flow-shop problem with the mean flow time criterion. This problem has obtained considerable attention, chiefly due to its industrial applications. Since the problem is NP-hard for two and more than two machines, a lot of approximation algorithms have been developed to provide a good solution in a quick time. Performance of each of these algorithms can be examined analytically (worst-case analysis, probabilistic analysis) or experimentally (computer tests on random instances). Most of the known approximation algorithms recommended for this problem have the worst-case performance ratio equal the number of jobs n. The best such the ratio, equal the number of machines m, have been found for an extension of the well-known SPT rule to m-machine flow-shop. We propose a new algorithm with the worst-case performance ratio upper bound [m/2]ρ, where ρ is the worst-case performance ratio of an algorithm which solves the auxiliary two-machine problem View full abstract»

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  • Cost optimization in supply management policies for assembly systems with random component yield times

    Publication Year: 1995 , Page(s): 445 - 453 vol.3
    Cited by:  Papers (1)
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    This paper addresses the problem of cost minimization in multi-product assembly systems where component yield times are subjected to random uncertainties. At the start of each cycle time, two interrelated decisions have to be made: 1) how many products to assemble for each product type; and 2) how many components to order. The total cost associated with these decisions is the sum of the inventory-holding cost and the product-backloging cost. A fast and efficient gradient-descent algorithm is applied to minimize the total cost over a given time horizon. The algorithm is based on the infinitesimal perturbation analysis (IPA) gradient estimation technique, and on continuous-parameter modeling formulation of the system's dynamics. Numerical experiments corroborate the conceptual developments View full abstract»

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  • On the selection of parts and processes during design of printed circuit board assemblies

    Publication Year: 1995 , Page(s): 241 - 248 vol.3
    Cited by:  Patents (1)
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    We consider a multiobjective optimization model that determines components and processes for given conceptual designs of printed circuit board assemblies. Specifically, our model outputs a set of solutions that are Pareto optimal with respect to a cost and a quality metric. The discussion here broadly outlines an integer programming based solution strategy, and represents in-progress work being carried out in collaboration with a manufacturing firm View full abstract»

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  • Fuzzy linguistic modeling and control of manufacturing systems

    Publication Year: 1995 , Page(s): 455 - 468 vol.3
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    Manufacturing processes are characterized by both discrete and continuous variable dynamics. The design of innovative and effective control strategies for these processes requires the development of new modeling techniques that not only capture the hybrid continuous/discrete dynamic nature of the process, but also address the performance objectives in a systematic way. It is also desirable that the modeling techniques address the controller design issue from a system-theoretic perspective. This paper introduces a new hierarchical approach for modeling of manufacturing systems in which the manufacturing plant is explicitly differentiated from the controller. A key feature of the proposed approach is the use of system-theoretic control concepts that capitalize upon tools from the area of fuzzy logic. An equivalence of this modeling approach with fuzzy Petri nets is described. An example is given that illustrates the design techniques View full abstract»

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  • Using evolutionary algorithms and simulation for the optimization of manufacturing systems

    Publication Year: 1995 , Page(s): 509 - 516 vol.3
    Cited by:  Papers (1)
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    This paper is concerned with an optimization method for manufacturing systems. This method is able to optimize problems with any type of variables (variables from a real set e.g. conveyor speed, an integer set e.g. size of buffer or any general set e.g. dispatching rules). It is based on the association of an evolutionary algorithm (EA) and a simulation model. Extensions of Michalewicz's genetic operators and algorithm (1992) are proposed to tackle manufacturing system problems. This method is applied to an example: the configuration of a workshop producing plastic yoghurt pots. The criterion to optimize is the cost of the workshop and the three variables are the size of a silo, the size of a warehouse and a choice between two manufacturing methods. The application has been realized by connecting a modified version of Michalewicz's Genocop software (for EA) and a simulation language View full abstract»

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  • Deadlock avoidance policy for manufacturing systems

    Publication Year: 1995 , Page(s): 141 - 152 vol.3
    Cited by:  Papers (6)
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    This work intends to give a contribution to the general problem of designing feasible schedules of generic manufacturing systems. The specific problem addressed in this paper is to understand the nature of deadlocks for generic manufacturing systems and find some rules that prevent a generic production system from entering a deadlock condition. A deadlock avoidance policy is proposed and discussed View full abstract»

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  • Integrated model and simulation of the production system

    Publication Year: 1995 , Page(s): 499 - 507 vol.3
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    Market constraints make it necessary for firms to take a global view and therefore to find a model permitting the integration of different functions of production. This aim is to develop a new approach based on three entities: process, functions, actors (PFA approach). The actors are all the human and material resources of the production system. The process represents all the logical mechanisms of thought and decision-making. The functions assure the link between the actors and the process. The PFA approach permits the integration of three levels of CIM: production management, supervision and workshop. It consists in integrating many of the existing modelling tools, when developing the model. In this way we have developed a modelling methodology which is broken down into four steps: 1. The use of the systemic approach to separate actors from process. 2. The use of the hierarchical approach to break down the production process into subprocesses. 3. The use of the object-oriented approach to model the actors. 4. The use of functions permitting the link between the process and the actors. The PFA approach allows to facilitate a simulation of an integrated model of the production system View full abstract»

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  • Continuous versus discrete flow of parts in a production dipole. Exact transient analysis

    Publication Year: 1995 , Page(s): 167 - 173 vol.3
    Cited by:  Papers (1)
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    In the dynamical description of production lines, the hydrodynamical framework to describe production flows of parts has been recognized to yield accurate results in numerous actual applications. The ”hydrodynamic approximation” consists in describing the population level in the buffers by a continuous variable. The aim of this paper is to compare analytically the results obtained in a simple production line composed of two identical failure prone machines separated by a buffer. In one case, a continuous flux of parts is produced by both machines while in the other case, we assume that each machine produces parts one by one with a processing time which is exponentially distributed. A direct comparison of the exact analytical results obtained in both situations enables us to characterize the operation regime for which the hydrodynamical model is a consistent analytical tool to model discrete flows, even for short time regimes. In this paper, we deal directly with calculation of probabilities and the resulting moments. We supplement our analysis with a comparison of the sojourn time of the population of parts inside the boundary of the buffer View full abstract»

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  • Reachability/controllability properties of internally proper PMDs

    Publication Year: 1995 , Page(s): 61 - 66 vol.3
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    An algorithm for obtaining an “equivalent” state-space representation of a linear multivariable system whose dynamics are expressed by internally proper polynomial matrix descriptions (PMDs) is used to analyze and examine certain pseudo-state and output controllability properties of the associated PMD View full abstract»

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  • A decomposition approach for performance evaluation of non-pipelined systems

    Publication Year: 1995 , Page(s): 195 - 203 vol.3
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    Although many schemes have been proposed for representing assembly systems, very few of them appear to be adequate for modelling commercially critical real-time issues such as throughput and performance. In this paper assembly systems are represented using timed Petri nets. We propose a three step approach to analysing the Petri net model for performance. The three steps involved are decomposition, grouping and analysis View full abstract»

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  • An application of neural networks to computer aided welding

    Publication Year: 1995 , Page(s): 317 - 325 vol.3
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    Within the context of integrated design, we propose a new approach for off-line programming of welding robots by interfacing a CAD modeler (geometric database) and an artificial intelligence system (welding database). The CAD system used to design pieces to be assembled, allows us to automatically generate welding trajectories and extract the assembly features needed to determine welding parameters. Using these features, we propose a new approach to generate automatically welding parameters, in GMAW process, with, neural networks. We have chosen to use backpropagation neural networks because this approach integrates database and modeling aspects. Moreover a neural nets based system is easily improvable, it can enlarge his field of application using new experimental welding data. The proposed method is able to determine the welding process and the welding wire to use and then to compute the welding parameters. We present in this paper the system we have developed with neural networks, the results we obtain and the possibilities of the method View full abstract»

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  • Modeling, simulation and control of event-driven operations in process systems

    Publication Year: 1995 , Page(s): 119 - 128 vol.3
    Cited by:  Papers (2)
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    The automation of batch processes poses difficult issues because it is necessary to concurrently deal with continuous and discrete models. In this paper we present a Petri net based approach which does not employ a unified framework based on extended Petri nets. Indeed, we do not try to integrate the continuous aspect within the framework of Petri net theory. In contrast, we establish a cooperation and powerful interaction between the Petri net model of the discrete aspect of the batch system and the continuous model which is a set of differential algebraic equations. This approach has been tested in the food industry for the validation of scheduling policies and is currently been developed for supervisory control and reactive scheduling View full abstract»

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  • Microrobotics, current of art and future

    Publication Year: 1995 , Page(s): 29 - 39 vol.3
    Cited by:  Papers (3)
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    This paper proposes the concept of micromachine, and presents the autonomous microrobot as an approach to develop the micromachine. Microdevices such as a microsensor, microactuator, and microprocessor are important for building an integrated microrobotic system, and are necessary for developing an autonomous microrobot. In this paper, we pay attention to not only the structure, but also the logic algorithm. A microrobot is considered to judge its motion based on restricted information and knowledge. The proposed autonomous microrobot, the “microline trace robot”, consists of a pair of electromagnetic mobile actuators, a pair of infrared sensors, and a programmable logic device, and controls itself by the simple logic algorithm View full abstract»

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  • Stochastic Petri nets simplification with singular perturbations

    Publication Year: 1995 , Page(s): 407 - 415 vol.3
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    In this paper, we introduce a new simplification of stochastic Petri net models. This simplification uses the singular perturbation method for discrete event systems in continuous time. We adapt this method for stochastic Petri net models. The model studied should have the double time scale property in order to apply this method of simplification. The decoupling method gives us two sub-systems, a fast and a slow evolution. These evolutions are the probabilities to be in a certain marking of the stochastic Petri net. For these two sub-systems, we only preserve the slow evolution of the marking probabilities, which yields the most precision given by the singular perturbation in continuous time. The main advantage of this method is to reduce the number of places and/or transitions of the stochastic Petri net. The calculation of the performance rates is then simplified. For complex stochastic Petri net models, this method allows one to draw the sub-system with a slow evolution View full abstract»

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  • Performance evaluation of kanban multiple-product production systems

    Publication Year: 1995 , Page(s): 557 - 566 vol.3
    Cited by:  Papers (5)
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    Kanban systems provide a way to implement a pull-type control policy. In this paper, we propose an analytical method for approximating the performance of a multiple-product kanban production system. This method uses the queueing network model of the kanban system, which is a closed multiclass queueing network (each class represents one type of kanban). It is based on the product-form approximation technique and is an extension of a previous method which had been programmed for mono-product kanban production systems with general topology. For multiple-product production systems, we can have several different types of products on a machine (we have restricted our study to only two types). So, we have a new problem: we must define the processing order of products. We can distinguish two cases according to set-up times. If set-up times are not null, we must try to limit the number of set-ups. But, if set-up times are null, we can choose the processing order without worrying about the limitation of set-ups number. We have realized the analysis for this second case in characterizing service time distributions with two moments. Finally, to test the method, we have compared analytical results to simulation results View full abstract»

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  • A framework to specify a reactive and proactive management system

    Publication Year: 1995 , Page(s): 251 - 259 vol.3
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    Industries, in a present context, must become more and more reactive. This reactivity depends on middle or long term tactical choices which have been carried out. Its efficiency implies a perpetual fitting from rules and parameters according to environment changes. It needs the implementation of a management system which we define as reactive and proactive. Such a management system must be characterized by a reactive behaviour, i.e. handling uncertainty and orders directly at operational level. It must also be characterized by a decision support system, the “proactive system”, which can adapt orders, rules, and/or parameters fixed to the operational management system according to the environment analysis and fitting with manufacturing models. Implementing such a management system implies the development of learning systems, models for cause/effects analysis and parameters fitting View full abstract»

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  • Work-in-progress optimization of cyclic manufacturing systems with assigned throughputs

    Publication Year: 1995 , Page(s): 471 - 477 vol.3
    Cited by:  Papers (2)
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    This paper shows that it is possible to formalize and to put in a proper form an optimization problem consisting in the optimization of the work-in-progress (WIP) in a manufacturing system, while ensuring a minimum value for the throughput of each product. The decision variables involved in this problem are the lot sizes for the various products and components and the system initial state, as regards the number of tokens in each place of the net. In spite of the limited modelling capability of timed event graphs, the considered structure of manufacturing systems is by no means trivial. Actually, the fact that the set of decision variables includes the lot sizes makes the production flows in the system optimized in practice. The main novelty of this paper with respect to previous works concerns the possibility of dealing with situations in which no machine acts as a bottleneck one. The optimization problem arising is thus more difficult than the two-level optimization problem View full abstract»

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  • Shop floor management using a fuzzy inference controller

    Publication Year: 1995 , Page(s): 271 - 278 vol.3
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    In this paper the authors propose a theoretical framework, based on fuzzy logic, to develop a shop floor controller. By recognizing that these weights are strongly influenced by the shop floor conditions, the authors introduce a fuzzy logic algorithm which determines both the jobs priorities and the corresponding weights applying a number of fuzzy rules. Since the rules premises are defined as fuzzy sets, the consequences are fuzzy sets themselves. Consequently, a defuzzification algorithm is applied View full abstract»

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