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Automation Science and Engineering, IEEE Transactions on

Issue 1 • Date Jan. 2007

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  • Table of contents

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  • IEEE Transactions on Automation Science and Engineering publication information

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  • The Development of Direct Metallic Rapid Tooling System

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4789 KB) |  | HTML iconHTML  

    In recent years, rapid tooling (RT) has become increasingly important because of the requirement of rapid manufacturing. RT can be used to produce temporary molds as well as permanent molds in mass production. RT provides more benefits from the design stage to mass production. The objective of this research is to develop the direct metallic RT system and identify process parameters of laser cladding. A 2.5-kW Nd-AG laser system, a metallic powder feeder system, a lateral powder nozzle system, a PC-based motion controller, and a shielding gas-supply system are incorporated for the hardware architecture in the proposed RT system. The critical process parameters influencing the dimensional accuracy were analyzed with Taguchi's experimental design. From the analysis of variance computational results, the factors "Scanning speed" and "Tool path offset" are the influential factors affecting the layer thickness of RT parts. From the experimental results, the dimensional accuracy of the dual nozzle RT system is better than the single-nozzle RT system. Finally, the proposed RT system could fabricate the mold inserts. After finishing the mold inserts and assembling the plenary injection mold, the injection molding machine can generate acrylonitrile butadiene styrene plastic parts with excellent quality. Note to Practitioners-Rapid prototyping (RP) technologies have provided a new way of making models or producing visualization prototype in a fast fashion. However, there is an urgent demand from the industry for much faster ways to make physical prototypes, with the desired material using the appropriate production method. RP technologies have introduced a new generation of RT processes. Producing tooling directly from computer-aided-design (CAD) models is regarded as an important process of reducing the cost and time to market for new products. In this paper, a direct metallic rapid tooling (RT) system is developed to fabricate the metallic parts and molds directly from 3-D - CAD models. The experimental investigations are implemented to study the proposed RT system. Using Taguchi's method, the critical performance process parameters have been analyzed. The analysis of variance method is used to decide the important process parameters. The developed RT system can produce the mold inserts directly. After assembling the plenary injection mold, the Acrylonitrile butadiene styrene ABS plastic parts have been generated from this RT mold to demonstrate the success of the process. In the future, it is possible to develop a grading alloy RT system, which can control the ratio of the alloy grading layers. Because the grading alloy rapid mold can use varied metallic powders with varied ratio, the cooling time and the residual stress can be reduced. Furthermore, the RT system can also adopt the coaxial nozzle which can be integrated with the optical system. The advantage of the coaxial nozzle is the independence of the powder supply direction in which the workpiece moves View full abstract»

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  • Volume Parameterization for Design Automation of Customized Free-Form Products

    Page(s): 11 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4565 KB) |  | HTML iconHTML  

    This paper addresses the problem of volume parameterization that serves as the geometric kernel for design automation of customized free-form products. The purpose of volume parameterization is to establish a mapping between the spaces that are near to two reference free-form models, so that the shape of a product presented in free-form surfaces can be transferred from the space around one reference model to another reference model. The mapping is expected to keep the spatial relationship between the product model and reference models as much as possible. We separate the mapping into rigid body transformation and elastic warping. The rigid body transformation is determined by anchor points defined on the reference models using a least-squares fitting approach. The elastic warping function is more difficult to obtain, especially when the meshes of the reference objects are inconsistent. A three-stage approach is conducted. First, a coarse-level warping function is computed based on the anchor points. In the second phase, the topology consistency is maintained through a surface fitting process. Finally, the mapping of volume parameterization is established on the surface fitting result. Compared to previous methods, the approach presented here is more efficient. Also, benefitting from the separation of rigid body transformation and elastic warping, the transient shape of a transferred product does not give unexpected distortion. At the end of this paper, various industry applications of our approach in design automation are demonstrated. Note to Practitioners-The motivation of this research is to develop a geometric solution for the design automation of customized free-form objects, which can greatly improve the efficiency of design processes in various industries involving customized products (e.g., garment design, toy design, jewel design, shoe design, and glasses design, etc.). The products in the above industries are usually composed of a very complex geometry sha- pe (represented by free-form surfaces), and is not driven by a parameter table but a reference object with free-form shapes (e.g., mannequin, toy, wrist, foot, and head models). After carefully designing a product around one particular reference model, it is desirable to have an automated tool for "grading" this product to other shape-changed reference objects while retaining the original spatial relationship between the product and reference models. This is called the design automation of a customized free-form object. Current commercial 3-D/2-D computer-aided design (CAD) systems, developed for the design automation of models with regular shape, cannot support the design automation in this manner. The approach in this paper develops efficient techniques for constraining and reconstructing a product represented by free-form surfaces around reference objects with different shapes, so that this design automation problem can be fundamentally solved. Although the approach has not been integrated into commercial CAD systems, the results based on our preliminary implementation are encouraging-the spatial relationship between reference models and the customized products is well preserved View full abstract»

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  • Diagnosis of Sheet Metal Stamping Processes Based on 3-D Thermal Energy Distribution

    Page(s): 22 - 30
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1795 KB) |  | HTML iconHTML  

    In this paper, a new approach is proposed using the 3-D thermal energy distribution of the workpiece. The new approach is based on the fact that during the stamping process, the workpiece absorbs energy to deform. This mechanical energy is converted into thermal energy. Therefore, it is possible to diagnose the stamping by analyzing the 3-D thermal energy distribution. In practice, the thermal energy distribution can be acquired using an infrared camera. However, it is often necessary to reconstruct the 3-D thermal energy distribution, which can be accomplished by using the Octree algorithm. On the other hand, one can compute the thermal energy distribution through finite-element modeling (FEM) as the baseline for diagnosis. Then, by comparison, the diagnosis can be carried out. A couple of examples are presented in detail together with the experiment validation. Note to Practitioners-These days computer-aided design (CAD) and finite-element modeling (FEM) are widely used for sheet metal stamping, especially in the automotive and aerospace industries. However, fault diagnosis and die tryout still rely heavily on the experiences of the engineers/machinists on the shop floor. An existing diagnosis method compares the strain distribution calculated using FEM and the experimental strain distribution, which is calculated from the measured deformation of the initial grid pattern. However, this method is time consuming as it requires the initial grid pattern preparation by either chemical etching or laser marking. This paper presents a new method for diagnosing sheet metal stamping processes. The new method compares the thermal distribution calculated using FEM and the experimental thermal distribution result, which can be acquired using an infrared (IR) camera. Therefore, it is more convenient to use it on the shop floor. The thermal FEM can be found based on strain FEM. However, the infrared image is 2-D and, hence, 3-D thermal distribution reconstruction is often necess- ary. This paper includes several practical examples. Some practical concerns, such as the conduction heat lost to the environment and the infrared camera viewing angles, are also discussed View full abstract»

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  • Online Fault Diagnosis of Discrete Event Systems. A Petri Net-Based Approach

    Page(s): 31 - 39
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (820 KB) |  | HTML iconHTML  

    This paper is concerned with an online model-based fault diagnosis of discrete event systems. The model of the system is built using the interpreted Petri nets (IPN) formalism. The model includes the normal system states as well as all possible faulty states. Moreover, it assumes the general case when events and states are partially observed. One of the contributions of this work is a bottom-up modeling methodology. It describes the behavior of system elements using the required states variables and assigning a range to each state variable. Then, each state variable is represented by an IPN model, herein named module. Afterwards, using two composition operators over all the modules, a monolithic model for the whole system is derived. It is a very general modeling methodology that avoids tuning phases and the state combinatory found in finite state automata (FSA) approaches. Another contribution is a definition of diagnosability for IPN models built with the above methodology and a structural characterization of this property; polynomial algorithms for checking diagnosability of IPN are proposed, avoiding the reachability analysis of other approaches. The last contribution is a scheme for online diagnosis; it is based on the IPN model of the system and an efficient algorithm to detect and locate the faulty state. Note to Practitioners-The results proposed in this paper allow: 1) building discrete event system models in which faults may arise; 2) testing the diagnosability of the model; and 3) implementing an online diagnoser. The modeling methodology helps to conceive in a natural way the model from the description of the system's components leading to modules that are easily interconnected. The diagnosability test is stated as a linear programming problem which can be straightforward programmed. Finally, the algorithm for online diagnosis leads to an efficient procedure that monitors the system's outputs and handles the normal behavior model. This provides an oppo- rtune detection and location of faults occurring within the system View full abstract»

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  • Effects of Classification Methods on Color-Based Feature Detection With Food Processing Applications

    Page(s): 40 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1799 KB) |  | HTML iconHTML  

    Color information is useful in vision-based feature detection, particularly for food processing applications where color variability often renders grayscale-based machine-vision algorithms that are difficult or impossible to work with. This paper presents a color machine vision algorithm that consists of two components. The first creates an artificial color contrast as a prefilter that aims at highlighting the target while suppressing its surroundings. The second, referred to here as the statistically based fast bounded box (SFBB), utilizes the principal component analysis technique to characterize target features in color space from a set of training data so that the color classification can be performed accurately and efficiently. We evaluate the algorithm in the context of food processing applications and examine the effects of the color characterization on computational efficiency by comparing the proposed solution against two commonly used color classification algorithms; a neural-network classifier and the support vector machine. Comparison among the three methods demonstrates that statistically based fast bounded box is relatively easy to train, efficient, and effective since with sufficient training data, it does not require any additional optimization steps; these advantages make SFBB an ideal candidate for high-speed automation involving live and/or natural objects. Note to Practitioners-Variability in natural objects is usually several orders of magnitude higher than that for manufactured goods and has remained a challenge. As a result, most solutions to inspection problems of natural products today still have humans in the loop. One of the factors influencing the success rate of color machine vision in detecting a target is its ability to characterize colors. When unrelated features are very close to the target in the color space, which may not pose a significant problem to an experienced operator, they appear as noise and often result in false detection- . This paper illustrates the applicability of the algorithm with a number of representative automation problems in the context of food processing applications. As demonstrated experimentally, the artificial color contrast and statistically based fast bounded box methods can significantly improve the success rate of the detection by reducing the standard deviation of both the target and noise pixels, enlarging the separation between feature clusters in color space, and more tightly characterize the feature color from its background. The algorithm presented here has several advantages, including simplicity in training and fast classification, since only three simple checks of rectangular bounds are performed View full abstract»

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  • Grasping Optimization Using a Required External Force Set

    Page(s): 52 - 66
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1199 KB) |  | HTML iconHTML  

    In this paper, we investigate optimal grasp points on an arbitrary-shaped grasped object using a required external force set. The required external force set is given based on a task, and consists of the external forces and moments, which must be balanced by virtue of contact forces applied by a robotic hand. When the origin is in the interior of the set, a force-closure grasp is required. When the dimension of the set is one, an equilibrium grasp is required. Therefore, we can investigate whatever the desired grasp is, such as when the desired grasp is a force closure and equilibrium grasps. Also, we only have to consider the forces contained in a given required external force set, not the whole set of possible resulting forces. Furthermore, we can avoid the frame-invariant problem (the criterion value changes with the change of the task (object) coordinate frame). We consider an optimization problem from the viewpoint of decreasing the magnitudes of the contact forces needed to balance any external force and moment contained in a given required external force set. In order to solve the problem, we present an algorithm based on a branch-and-bound method. We also present some numerical examples to show the validity of our approach. Note to Practitioners-This paper is concerned with grasping an object by a robotic hand. This article address how to grasp the object, namely, how to position every finger on the object. Recently, robots are desired to be used in housekeeping and in caring for elderly people. For this purpose, robot (multifingered) hands are equipped with the robots as general-purpose end effectors. The robot hands are required to automatically move to accomplish such tasks. In this case, the most fundamental issue for robot hands is to grasp the object. At home, there are many various-shaped objects. Consider the case where the robot (hand) is commanded to perform a certain task, such as putting the object into a box. In this case, the robot (hand) must - grasp such an object (of any arbitrary shape) with appropriate grasp positions for completing the task. Therefore, the appropriate grasp positions must be calculated automatically. This article addresses a method to solve this problem. But to complete the grasping task, the following problems remain: calculation and control of the appropriate grasping forces View full abstract»

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  • Design of Multiunit Electronic Exchanges Through Decomposition

    Page(s): 67 - 74
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (319 KB) |  | HTML iconHTML  

    In this paper, we exploit the idea of decomposition to match buyers and sellers in an electronic exchange for trading large volumes of homogeneous goods, where the buyers and sellers specify marginal-decreasing piecewise constant price curves to capture volume discounts. Such exchanges are relevant for automated trading in many e-business applications. The problem of determining winners and Vickrey prices in such exchanges is known to have a worst-case complexity equal to that of as many as (1+m+n) NP-hard problems, where m is the number of buyers and n is the number of sellers. Our method proposes the overall exchange problem to be solved as two separate and simpler problems: 1) forward auction and 2) reverse auction, which turns out to be generalized knapsack problems. In the proposed approach, we first determine the quantity of units to be traded between the sellers and the buyers using fast heuristics developed by us. Next, we solve a forward auction and a reverse auction using fully polynomial time approximation schemes available in the literature. The proposed approach has worst-case polynomial time complexity and our experimentation shows that the approach produces good quality solutions to the problem. Note to Practitioners- In recent times, electronic marketplaces have provided an efficient way for businesses and consumers to trade goods and services. The use of innovative mechanisms and algorithms has made it possible to improve the efficiency of electronic marketplaces by enabling optimization of revenues for the marketplace and of utilities for the buyers and sellers. In this paper, we look at single-item, multiunit electronic exchanges. These are electronic marketplaces where buyers submit bids and sellers ask for multiple units of a single item. We allow buyers and sellers to specify volume discounts using suitable functions. Such exchanges are relevant for high-volume business-to-business trading of standard products, such as silicon wafers, very larg- e-scale integrated chips, desktops, telecommunications equipment, commoditized goods, etc. The problem of determining winners and prices in such exchanges is known to involve solving many NP-hard problems. Our paper exploits the familiar idea of decomposition, uses certain algorithms from the literature, and develops two fast heuristics to solve the problem in a near optimal way in worst-case polynomial time View full abstract»

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  • Manufacturing System Design to Improve Quality Buy Rate: An Automotive Paint Shop Application Study

    Page(s): 75 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (159 KB) |  | HTML iconHTML  

    Manufacturing system design has an impact on product quality. In this paper, we investigate this impact through an application study at an automotive paint shop. Specifically, for repair and rework systems in paint operations, we develop a model to quantify paint quality [in terms of quality buy rate (QBR)] as a function of repair capacity. We show that the QBR can be improved and unnecessary repaints can be reduced by increasing the repair capacity. Note to Practitioners-Manufacturing system design and quality management are important in many manufacturing industries. Although they have attracted substantial research effort, little attention has been paid to address the coupling or interactions between system design and product quality. Empirical evidence and analytical studies have shown that manufacturing system design does impact quality. In this paper, through an application study at a repair and rework system in an automotive paint shop, we show that paint quality, as measured by the quality buy rate, can be improved by designing the system more effectively. Similar problems are also often encountered in other manufacturing systems. Results obtained in this work, along with other results, demonstrate both the theoretical and practical importance of the analysis of manufacturing system design on product quality, and suggest a largely unexplored, but promising research area View full abstract»

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  • Social Foraging Theory for Robust Multiagent System Design

    Page(s): 79 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (265 KB) |  | HTML iconHTML  

    An analogy between an agent (e.g., an autonomous vehicle) and a biological forager is extended to a social environment by viewing a communication network as implementing interagent sociality. We first describe engineering design within an evolutionary game-theoretic framework. We then explain why sociality may emerge in some environments and for some agent objectives. Next, we derive the evolutionarily stable design strategy for an agent manufacturer: 1) choosing whether the agent it produces should cooperate with other agents in a search problem and 2) choosing the group size of a multiagent system tasked with a cooperative search problem. We show the impact of "agent relatedness," a measure of common descent between two agents based on their underlying manufacturers, on the choices in scenarios 1) and 2). Our predictions are evaluated in an autonomous vehicle simulation testbed. The results illustrate a new methodology for manufacturers to make robust, optimal choices for multiagent system design for a given set of objectives and domain of operation. Note to Practitioners-The design of autonomous multirobot systems with various applications, such as in parts production or search and destroy operations in a military environment, is of growing importance. Here, we integrate economic and technical issues into an unified engineering design framework for the manufacturers of robots. Our approach leads to manufacturer design decisions that are robust relative to the market for a manufacturer's products. Robot component aspects, such as sensors and communications as well as mission performance aspects, can be captured and coupled into the design process. We use the design of intervehicle cooperation and robot group size to illustrate this approach. The practical significance lies in the fact that we take a broad perspective on engineering design, one closer to the real world, due to the considerations of marketplace economics. Moreover, the approach provides a framework- to study design choices that escape systematic analysis in other frameworks (e.g., group size) View full abstract»

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  • A Case Study on Integrated Production Planning and Scheduling in a Three-Stage Manufacturing System

    Page(s): 86 - 92
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (349 KB) |  | HTML iconHTML  

    This paper presents an integrated optimization model of production planning and scheduling for a three-stage manufacturing system, which is composed of a forward chain of three kinds of workshops: a job shop, a parallel flow shop consisting of parallel production lines, and a single machine shop. As the products at the second stage are assembled from the parts produced in its upstream workshop, a complicated production process is involved. On the basis of the analysis of the batch production, a dynamic batch splitting and amalgamating algorithm is proposed. Then, a heuristic algorithm based on a genetic algorithm (known as the integrated optimization algorithm) is proposed for solving the problem. Note to Practitioners-This paper presents a method for integrated production planning and scheduling in a three-stage manufacturing system consisting of a forward chain of three kinds of workshops, which is common in such enterprises as producers of automobiles and household electric appliances, as in the case of an autobody plant usually with the stamping workshop, the welding and assembling workshop, and the painting workshop. Herein, the production planning and scheduling problems are simultaneously addressed in the way that a feasible production plan can be obtained and the inventory reduced. A batch splitting and amalgamating algorithm is proposed for balancing the production time of the production lines. And a case study of the integrated planning and scheduling problem in a real autobody plant verifies the effectiveness of our method View full abstract»

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  • A Small Model Theorem for Bisimilarity Control Under Partial Observation

    Page(s): 93 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (285 KB) |  | HTML iconHTML  

    This paper extends our prior result on decidability of bisimulation equivalence control from the setting of complete observations to that of partial observations. Besides being control compatible, the supervisor must now also be observation compatible. We show that the "small model theorem" remains valid by showing that a control and observation compatible supervisor exists if and only if it exists over a certain finite state space, namely the power set of the Cartesian product of the system and the specification state spaces. Note to Practitioners-Non-determinism in discrete-event systems arises due to abstraction and/or unmodeled dynamics. This paper addresses the issue of control of non-deterministic systems subject to non-deterministic specifications, under a partial observation of events. Non-deterministic plant and specification are useful when designing a system at a higher level of abstraction so that lower level details of the system and its specification are omitted to obtain higher level models that are non-deterministic. The control goal is to ensure that the controlled system has an equivalent behavior as the specification system, where the notion of equivalence used is that of bisimilarity. Bisimilarity requires the existence of an equivalence relation between the states of the two systems so that transitions on common events beginning from a pair of equivalent states end up in a pair of equivalent successor states. Supervisors are also allowed to be nondeterministic, where the nondeterminism in control is implemented by selecting control actions nondeterministically from among a set of precomputed choices. The main contribution of this paper is to show that a supervisor exists if and only if one exists where the size of its state-space upper bounded and so it suffices to search over this state space. We illustrate our results through a manufacturing example View full abstract»

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  • A Resource Allocation Algorithm for Multivehicle Systems With Nonholonomic Constraints

    Page(s): 98 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (779 KB) |  | HTML iconHTML  

    This paper is about the allocation of tours of m targets to n vehicles. The motion of the vehicles satisfies a nonholonomic constraint (i.e., the yaw rate of the vehicle is bounded). Each target is to be visited by one and only one vehicle. Given a set of targets and the yaw rate constraints on the vehicles, the problem addressed in this paper is 1) to assign each vehicle a sequence of targets to visit, and 2) to find a feasible path for each vehicle that passes through the assigned targets with a requirement that the vehicle returns to its initial position. The heading angle at each target location may not be specified. The objective function is to minimize the sum of the distances traveled by all vehicles. A constant factor approximation algorithm is presented for the above resource allocation problem for both the single and the multiple vehicle case. Note to Practitioners-The motivation for this paper stems from the need to develop resource allocation algorithms for unmanned aerial vehicles (UAVs). Small autonomous UAVs are seen as ideal platforms for many applications, such as searching for targets, mapping a given area, traffic surveillance, fire monitoring, etc. The main advantage of using these small autonomous vehicles is that they can be used in situations where a manned mission is dangerous or not possible. Resource allocation problems naturally arise in these applications where one would want to optimally assign a given set of vehicles to the tasks at hand. The feature that differentiates these resource allocation problems from similar problems previously studied in the literature is that there are constraints on the motion of the vehicle. This paper addresses the constraint that captures the inability of a fixed wing aircraft to turn at any arbitrary yaw rate. The basic problem addressed in this paper is as follows: Given n vehicles and m targets, find a path for each vehicle satisfying yaw rate contraints such that each target is visited exactly once by- a vehicle and the total distance traveled by all vehicles is minimized. We assume that the targets are at least 2r apart, where r is the minimum turning radius of the vehicle. This is a reasonable assumption because the sensors on these vehicles can map or see an area whose width is at least 2r. We give an algorithm to solve this problem by combining ideas from the traveling salesman problem and the path planning literature. We also show how these algorithms perform in the worst-case scenario View full abstract»

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  • On the Use of UML for Modeling Mechatronic Systems

    Page(s): 105 - 113
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB) |  | HTML iconHTML  

    This paper describes a modeling language that aims to provide a unified framework for representing control systems, namely, physical plants coupled with computer-based control devices. The proposed modeling methodology is based on the cardinal principle of object orientation, which allows describing both control software and physical components using the same basic concepts, particularly those of capsules, ports, and protocols. Furthermore, it is illustrated how the well-known object-oriented specification language unified modeling language can be adopted, provided an adequate formalization of its semantics, to describe structural and behavioral aspects of control systems, related to both logical and physical parts. Note to Practitioners-The development of an automated system within an industrial setting is a complex task, whose successful result depends on the joint efforts of a team of designers with different scientific backgrounds and specialized knowledge. In fact, an automated system is typically composed of a mechanical assembly, which must be precisely designed and manufactured, and a set of sensors and actuators (e.g., electrical drives, pneumatic systems, etc.), which are, on their turn, controlled most of the time by means of digital processors. Of course, both electrical parts and control algorithms (e.g., proportional, integral, and derivative (PID) regulators, logic and supervisory control, reference trajectories for mechanical motions, etc.) should be designed with the same care given to mechanical aspects. Moreover, it is undeniable that none of the various parts composing the automated system design specification can, on their own, allow engineers to understand the actual behavior of the whole system, especially without a common description language that is understandable for all of the designers. The present paper introduces a unified language which aims to support integrated design specifications of automated systems, including the dynamics of het- erogeneous physical assemblies, the discrete-event behavior of distributed control software, and the specification of interface ports between the plant and the control system. With the proposed language, it is possible to obtain a complete picture of the automated system suitable for its simulation, documentation, and validation. The modeling language described in the paper supports the principles of object orientation. This choice moves in the direction of enhancing modularity and reusability properties of design specifications, which are aspects of great importance in the design practice. Moreover, the object-oriented approach to automated systems design proposed in the paper aims to introduce the concept of "design by extension" in the manufacturing industry. This means that the definition of specialization relationships between classes of components implies that those components should be designed in order to be substitutable with each other, especially from a dynamic point of view. This aspect will be the subject of further papers illustrating other practical insights on the use of object-oriented models for automated systems View full abstract»

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  • Diagnosis of DES With Petri Net Models

    Page(s): 114 - 118
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (270 KB) |  | HTML iconHTML  

    The diagnosis of discrete event systems is strongly related to events estimation. This paper focuses on faulty behaviors modeled with ordinary Petri nets with some "fault" transitions. Partial but unbiased measurement of the places marking variation is used in order to estimate the firing sequences. The main contribution is to decide which sets of places must be observed for the exact estimation of some given firing sequences. Minimal diagnosers are defined that detect and isolate the firing of fault transitions immediately. Causality relationships and directed paths are also investigated to characterize the influence and dependence areas of the fault transitions. Delayed diagnosers are obtained as a consequence. Note to Practitioners-Structural tools are provided for the analysis of models used in the context of fault detection and isolation for discrete event systems. The systems that are concerned are either manufacturing processes, batch processes, digital devices, or communication protocols with single or multiple failures. Methods are proposed to decide, in a systematic way, if the considered failures can be detected and isolated according to the existing sensors. The obtained results can also be used by designers for sensor selection View full abstract»

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  • Automated Pipe Defect Detection and Categorization Using Camera/Laser-Based Profiler and Artificial Neural Network

    Page(s): 118 - 126
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1374 KB) |  | HTML iconHTML  

    Closed-circuit television (CCTV) is currently used in many inspection applications, such as the inspection of nonaccessible pipe surfaces. This human-oriented approach based on offline analysis of the raw images is highly subjective and prone to error because of the exorbitant amount of data to be assessed. Laser profilers have been recently proposed to project well-defined light patterns, improving the illumination of standard CCTV systems as well as enhancing the capability of automating the assessment process. This research shows that positional (geometrical) as well as intensity information, related to potential defects, can be extracted from the acquired laser projections. While most researchers focus on the analysis of positional information obtained from the acquired profiler signals, here the intensity information contained within the reflected light is also exploited for the purpose of defect classification and visualization. This paper describes novel strategies created for the automation of defect classification in tubular structures and explores new methods to fuse intensity and positional information, achieving improved multivariable defect classification. The acquired camera/laser images are processed in order to extract signal information for the purpose of visualization and map creation for further assessment. Then, a two-stage approach based on image processing and artificial neural networks is used to classify the images. First, a binary classifier identifies defective pipe sections, and then in a second stage, the defects are classified into different types, such as holes, cracks, and protruding obstacles. Experimental results are provided. Note to Practitioners-The method presented in this paper aims to automate the inspection of nonaccessible pipe surfaces. The method was thought to be employed in the inspection of sewers; however, it could be used in many other industrial applications and could also be extended to other shapes rather than tubul- ar structures. A laser ring profiler, consisting, for instance, of a laser diode and a ring projector, can be easily integrated into existing closed-circuit television systems. The proposed algorithm identifies defective areas and categorizes the types of defects, analyzing the successive recorded camera images that will contain the reflected ring of light. The algorithm, that can be used online, makes use of the deformation of the reflected laser ring together with its changes in intensity. The fact of combining the two kinds of data using artificial-intelligent algorithms makes the method robust enough to work in harsh environments View full abstract»

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  • Special issue on automation and engineering for ambient intelligence

    Page(s): 127
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    Freely Available from IEEE
  • Special issue on RFID systems

    Page(s): 128
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    Freely Available from IEEE
  • IEEE Robotics and Automation Society Information

    Page(s): C3
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    Freely Available from IEEE
  • IEEE Transactions on Automation Science and Engineering Information for authors

    Page(s): C4
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Aims & Scope

T-ASE will publish foundational research on Automation: scientific methods and technologies that improve efficiency, productivity, quality, and reliability, specifically for methods, machines, and systems operating in structured environments over long periods, and the explicit structuring of environments.

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Meet Our Editors

Editor-in-Chief
Ken Goldberg
University of California, Berkeley