Browsing by Author "Lee, JS"

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A new approach to evaluate ladder logic diagrams and Petri nets via the IF-THEN transformation
(2002)
Lee, JS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The `basic element' approach has been proposed for evaluating the complexity of sequence control designs using the ladder logic diagram (LLD) and Petri net (PN). Whereas basic elements in the LLD stand for push buttons, limited switches, relay coils, timers, counters, solenoids, and lines, they are places, transitions, and arcs in the PN. Since basic elements for different structures have different physical meanings, the basic element approach may lead to misleading comparison and unreliable results. Thus, a suitable and unified measure for analyzing the LLD and PN is pursued. In this paper, a new approach via the IF-THEN transformation is proposed. The same measure obtained from the IF-THEN rules and corresponding logic operators can then be suitably applied to both LLD and PN. The provided example is of five sequences with increasing complexity for a stamping process. It indicates that the proposed IF-THEN transformation is more appropriate than the basic element approach in real applications. Moreover, results clearly show that the PN is more suitable than LLD for sequence control design as processes become more complex.
A Petri-net approach to hierarchical supervision for remote-controlled processes
(2003)
Lee, JS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
For remote-controlled multi-recipe processes, certain issued commands may lead to undesired resource conflicts and deadlock states. Moreover, as a result of the communication delay and packet loss in the Internet, remote control of a group of certain steps are recommended rather than control of each step. For these Web-based control systems, this paper proposes a three-level,architecture for hierarchical supervision. In the upper supervisory level, the supervisory agent guarantees that issued commands from the remote manager, in the middle command level, satisfy the resource sharing and deadlock-free requirements when executing a number of concurrent recipes, while the local controller, in the lower control level, performs the corresponding detailed operations to meet the requested tasks. In the present approach, Petri nets (PNs) are used to model, design, and verify the supervisory agent and local controller, and then, Java technology and ladder logic diagrams (LLDs) are adopted for implementation to achieve online supervision of the remote-controlled processes. To demonstrate the practicability of the developed supervisory approach, we apply it to a three-recipe flexible manufacturing system (FMS) controlled over the Internet.
A PLC-based design for the sequence controller in discrete event systems
(2000)
Lee, JS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Recently, methods have been proposed for obtaining the ladder logic diagram (LLD) based on the Petri net (PN). However, those resulting LLDs are usually not in compact forms. Moreover, forming the PN structures to model manufacturing processes is not straightforward. In this paper, we propose a simplified Petri net controller (SPNC) by introducing sensor states into the PN. A compact LLD can be then obtained through the token passing logic (TPL). By employing the integration definition language 0 (IDEF0) technique, we obtain the SPNC structure sequentially through diagrams. The result of an integrated IPTL (IDEF0/SPNC/TPL/LLD) algorithm, including the IDEF0, SPNC, and TPL tools, leads to the standard IEC1131-3 LLD for PLC implementation. An example of a mark stamping system is provided to illustrate the developed material The flow diagrams and information design approach.
A real time collaboration system for teleradiology consultation
(2003-12-01)
Lee, JS
;
Tsai, CT
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Pen, CH
;
Lu, HC
;
資訊工程學系
Real time collaboration systems, in which participants share multimedia data and applications in real time, have attracted many researchers in recent years. A teleradiology consultation system based on the real time collaboration technology is presented in this paper. Under the platform-independence consideration, Java technologies are employed to construct the system. Applying this system, an off-duty on-call radiologist can make diagnoses and report easily by viewing the transferred images at home. Owing to the accessibility of image, all users can examine and manipulate images consistently such that a secluded hospital can be assisted to hold remote consultation. To reduce the network transmission time, the command-passing and local command execution techniques are utilized to achieve the screen synchronization. A pointer function is also developed to maintain the cursor consistency in a more efficient manner during consultation when a detail indication of the examined image is needed. Besides, a dialog window is also designed for on-line conversation. Since Java programs can run on heterogeneous platforms, the need for system maintenance and user training can be substantially reduced. (C) 2003 Elsevier Ireland All rights reserved.
A systematic approach for the sequence controller design in manufacturing systems
(2005)
Lee, JS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a systematic approach for the design and implementation of the sequence controller in manufacturing systems. By employing the IDEF0, we construct the simplified Petri net controller (SPNC) through the material flow diagram and the information flow diagram. Then, the ladder logic diagram (LLD) can be transformed from the SPNC through the token passing logic (TPL). The proposed approach, including the IDEF0, SPNC, and TPL tools, leads to the standard IEC1131-3 LLD for PLC implementation. Finally, an application of a stamping process is provided to illustrate the design procedure of the developed approach.
An application of Petri nets to supervisory control for human-computer interactive systems
(2005-10-01)
Lee, JS
;
Zhou, MC
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In a distributed robotic system, both human-controlled (semi-autonomous) and computer-controlled (fully autonomous) robots may simultaneously exist. From the global system's point of view, supervisory control for the interactions between the human and computer are important and necessary. For such human-computer interactive systems, this paper proposes a supervisory framework to guarantee that both human and computer commands meet collision-free and deadlock-free requirements. In the presented approach, Petri nets are applied to construct a system model and synthesize a desired supervisor. An application to a two-robot remote surveillance system is provided to demonstrate the practicability of the developed supervisory control approach. It is believed that the technique developed in this paper is significant in the industrial practice.
An IDEF0/Petri net approach to the system integration in semiconductor manufacturing systems
(2003)
Lee, JS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
For complex and large-scale semiconductor manufacturing systems, using real devices for system integration and testing not only increases the cost but also takes a longer time. In this paper, a systematic approach for the emulator design of the manufacturing equipment to achieve system integration is proposed. In the proposed approach, the integration definition language 0 (IDEF0) and Petri net (PN) are applied to perform the functional and behavior analyses of the equipment, and then a verified PN model can be obtained for the implementation of emulators. An application of a rapid thermal process (RTP) in semiconductor manufacturing systems is provided to illustrate the design procedure of the developed approach.
An improved evaluation of ladder logic diagrams and Petri nets for the sequence controller design in manufacturing systems
(2004-08-01)
Lee, JS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Sequence controller designs play a key role in advanced manufacturing systems. Traditionally, the ladder logic diagram (LLD) has been widely applied to programmable logic controllers (PLC), while recently the Petri net (PN) has emerged as an alternative tool for the sequence control of complex systems. The evaluation of both approaches has become crucial and has thus attracted attention. The "basic element" approach was developed to evaluate the complexity and flexibility for LLD and PN design approaches [1, 2, 3, 4]. However, the basic elements of these two designs are inherently different and hence that approach may lead to unreliable results. Since sequence control here naturally implies the use of logic rules, a rule-based approach is proposed in this paper to provide unified measures for both LLD and PN designs. To illustrate the proposed approach, it is applied to five control sequences with increasing complexity for a stamping process. Results indicate that the proposed approach is more suitable for real applications and, furthermore, PN is increasingly superior to LLD as the control sequence becomes more complex.
An object-oriented design of the hybrid controller for automated vehicles in an AHS
(2002)
Lee, JS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Recently, designs for the automated highway systems (AHS) to improve the safety and efficiency of highways have attracted much attention. However, such large-scale and complex dynamic systems present a number of control issues. Part of the complication comes from the hybrid nature of these systems, which consists of both time-driven and event-driven dynamics. In this paper, an object-oriented approach towards a hybrid controller design for automated vehicles in an AHS is proposed. First, the unified modeling language (UML) is extended to model the hybrid controller with a clear and natural representation of the discrete event and continuous time behaviors. Then, since the AHS is typically a multi-agent system, the simulation of which is suitable to implementation by multi-threaded programming, a Java-based library is further developed to support the implementation. In our framework, Java provides an implementation path, while the extended UML provides a reverse: engineering path for the hybrid controller design.
Design and implementation of the SNMP agents for remote monitoring and control via UML and Petri nets
(2004-03-01)
Lee, JS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
For large-scale find long-distance distributed systems, this paper proposes a systematical multiparadigm approach to develop the simple network management protocol (SNMP) agents for remote monitoring and control. The standard unified modeling language (UML) is adopted for modeling the system, and then the Petri-net model is applied to achieve both qualitative and quantitative analyses for the system's dynamic behavior. In real applications, the present design can be further implemented with Java and ladder diagrams on programmable logic controllers (PLC). The developed system has been used successfully in a mobile switching center (MSC) of Taiwan Cellular Corporation for the remote monitoring and control, through the Internet, of its environmental conditions, including the temperature, humidity, power, and security, with a total of 316 sensors and 140 actuators.
Design of remote environmental monitoring systems
(2002)
Lee, JS
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Hsu, PL
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電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, a remote environmental monitoring system with the simple network management protocol (SNMP) is developed. The development process is integrated based on the standard unified modeling language (UML) and the verifiable Petri-net model. Thus, the dynamic behaviors of the remote monitoring system can be analyzed by using the Petri-net theory. Finally, the system can be implemented by using the Java. A case study of an environmental monitoring system for the mobile switching center (MSC) is provided to illustrate the design approach.
Effect of the core-shell impact modifier shell thickness on toughening PVC
(2004-10-01)
Lee, JS
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Chang, FC
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應用化學系
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Department of Applied Chemistry
The shell thickness of a core/shell impact modifier is found to be the single most important factor in the toughening of rigid polyvinyl chloride (PVC). When the shell thickness is greater than a critical value of 15.8 nm, these core-shell elastomeric particles are able to remain structurally intact and well dispersed within the PVC matrix after melt blending. However, too thick a shell thickness results in a hard core (high modulus) of these core/shell particles and loss of the rubbery nature required of an efficient impact modifier. Therefore, these over-thick particles can act only as rigid fillers. not as efficient rubbery modifiers. On the other hand, when the shell thickness is less than the critical value of 4.9 nm, too thin a shell layer is simply unable to fully protect and cover the inner rubbery core during vigorous processing conditions, and these core-shell particles tend to connect with one another through the partially exposed core to form a cellular-like structure, thus resulting in poor toughening efficiency. Regardless of the particle size, as long as the shell thickness of these core/shell elastomers is between these two critical values (15.8 nm and 4.9 nm), they all display high efficiency in toughening rigid PVC. (C) 2004 Society of Plastics Engineers.
Glass transition temperatures of poly(hydroxystyrene-co-vinylpyrrolidone-co-isobutylstyry1 polyhedral oligosilsesquioxanes)
(2002-09-01)
Xu, HY
;
Kuo, SW
;
Lee, JS
;
Chang, FC
;
應用化學系
A series of poly(hydroxystyrene-co-vinylpyffolidone-co-isobutylstyryl polyhedral oligosilsesquioxanes) (PHS-PVP-POSS) hybrid polymers with various POSS contents was prepared by free radical copolymerization of acetoxystyrene, vinylpyrrolidone with styrylisobutylpolyhedral oligosilsesquioxanes (POSS), followed by selective removal of the acetyl protective group. The POSS content of a hybrid polymer can be effectively controlled by varying the feed ratios of reactants. The T-g of the POSS hybrid increases with the POSS content of PHS-PVP-POSS hybrids. The mechanism of T-g enhancement in these PHS-PVP-POSS hybrids was investigated using DSC, FTIR and GPC. The formation of the physically cross-linked POSS in these hybrid polymers trends to restrict polymer chain motion and results in significant T-g increase. (C) 2002 Published by Elsevier Science Ltd.
Optimal quantitative group testing on cycles and paths
(2001-10-15)
Hwang, FK
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Lee, JS
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應用數學系
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Department of Applied Mathematics
We determine the minimum number of group tests required to search for a special edge when the graph consists of cycles and paths, generalizing previous results of Aigner on paths and on a simple cycle. (C) 2001 Elsevier Science B.V. All rights reserved.
Path planning of 3-D objects using a new workspace model
(2001-01-01)
Tsai, CH
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Lee, JS
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Chuang, JH
;
資訊工程學系
;
Department of Computer Science
This paper proposes a collision avoidance algorithm to solve the problem of (local) path planning for a 3-D object moving among polyhedral obstacles. The algorithm is based on a generalized potential model of workspace [1] which assumes that the boundary of every 3-D object is uniformly charged. According to the proposed approach, the repulsive force and torque between the moving object and the obstacles due to the above model is used to adjust the position and orientation of the object so as to keep it away from the obstacles while passing through a bottleneck in the free space. Simulation results demonstrate that the path of a 3-D object thus obtained is indeed safe and spatially smooth. The adopted potential field is analytically tractable which makes the path planning efficient.
Path planning of 3-D objects using a new workspace model
(2001-08-01)
Tsai, CH
;
Lee, JS
;
Chuang, JH
;
資訊工程學系
;
Department of Computer Science
This paper proposes a collision avoidance algorithm to solve the problem of (local) path planning for a three-dimensional (3-D) object moving among polyhedral obstacles. The algorithm is based on a generalized potential model of workspace [1] which assumes that the boundary of every 3-D object is uniformly charged. According to the propose approach, the repulsive force and torque between the moving object an the obstacles due to the above model is used to adjust the position and orientation of the object so as to keep it away from the obstacles while passing through a bottleneck in the free space. Simulation results demonstrate that the path of a 3-D object thus obtained is indeed safe and spatially smooth. The adopted potential field is analytically tractable which makes the path planning efficient.
Permutation polytopes corresponding to strongly supermodular functions
(2004-08-15)
Hwang, FK
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Lee, JS
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Rothblum, UG
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應用數學系
;
Department of Applied Mathematics
Throughout, let p be a positive integer and let Sigma be the set of permutations over {1,....p}. A real-valued function lambda over subsets of {1,... p}, with lambda(theta)=0, defines a mapping of Sigma into R-p where delta is an element of Sigma is mapped into the vector lambda(delta) whose kth coordinate (lambda(delta))(k) is the augmented-value obtained from adding k to the coordinates that precede it, according to the ranking induced by sigma. The permutation polytope corresponding to is then the convex hull of the vectors corresponding to all permutations. We introduce a new class of strongly supermodular functions and for such functions we derive an isomorphic representation for the face-lattices of the corresponding permutation polytope. (C) 2003 Elsevier B.V. All rights reserved.
Petri net-based design of modular supervisors for remotely human control systems
(2004)
Lee, JS
;
Zhou, MC
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In an Internet-based control system, particular human operations may violate desired requirements and lead to destructive failure. For such human-in-the-loop systems, this paper extends the remote supervisory scheme in [5] to a modular one so as to reduce the supervisor synthesis complexity. Also, remote human issued commands are guaranteed to meet required specifications. A rapid thermal process in semiconductor manufacturing systems is provided to show the practicability of the proposed approach.
Preparations, thermal properties, and T-g increase mechanism of inorganic/organic hybrid polymers based on polyhedral oligomeric silsesquioxanes
(2002-11-05)
Xu, HY
;
Kuo, SW
;
Lee, JS
;
Chang, FC
;
應用化學系
A series of novel hybrid poly(acetoxylstyrene-co-isobutylstyryl-POSS)s (PAS-POSS) and poly(vinylpyrrolidone-co-isobutylstyryl-POSS)s (PVP-POSS) are synthesized and characterized. The POSS content in these hybrids can be controlled by varying the monomer feed ratio. The polyhedral oligosilsesquoixane (POSS) moiety can effectively increase the T-g of the resultant organic/inorganic hybrid polymer at a relatively high POSS content and produce the hybrid copolymer with narrower molecular weight distribution. The FTIR spectra are used to investigate the structure-property relationship of these hybrid polymers, and the T-g enhancement mechanism is discussed in detail.
Remote supervisory control of the human-in-the-loop system by using Petri nets and Java
(2003-06-01)
Lee, JS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
For internet-based remote control systems, certain human operations may violate desired safety requirements and result in catastrophic failure. For such human-in-the-loop systems, this paper proposes a systematic approach to developing supervisory agents which guarantee that remote manual operations meet safety specifications. By applying the mutual exclusion concept, the Petri net approach is used to model, design, and verify it supervisory system which prevents human,errors. Then, Java technology is adopted to implement the supervisor as an intelligent agent for online supervision of the remote control system. To demonstrate the feasibility and practicability of the developed supervisory approach, we apply it to a rapid thermal processor controlled over the Internet.