Browsing by Author "Hsu, PL"

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A new approach to biaxial cross-coupled control
(2000)
Yeh, SS
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Hsu, PL
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電控工程研究所
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Institute of Electrical and Control Engineering
Cross-coupled control (CCC) has been developed to improve contouring performance for biaxial contour motion systems. However, it is complicated to apply the CCC to arbitrary contour motion because additional calculations are required to obtain the variable cross-coupling gains. In this paper, a new approach to CCC is proposed to efficiently reduce the computation of cross-coupling gains for arbitrary contour commands. According to the analysis of variable gain cross-coupled control, the magnitude and direction of the contouring error can be used to determine the value and direction to be applied in contour compensation for each axis. Thus, the contouring error vector is used here to derive the new CCC approach. The estimated contouring error vector is defined as a vector from the actual position to the nearest point of the line that passes through the reference position tangentially. Thus, the implementation of CCC becomes much more direct with only one simple formulation for cross-coupling gains. Finally, the experimental results on a CNC machining center show that the proposed CCC approach efficiently reduces the contouring error during arbitrary contour motion. Moreover, the calculations required to obtain the variable gains of the CCC are significantly reduced.
A new approach to evaluate ladder logic diagrams and Petri nets via the IF-THEN transformation
(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
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
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Hsu, PL
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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
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Hsu, PL
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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 practical design for a multivariable proportional-integral controller in industrial applications
(1997-07-01)
Hwang, DS
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Hsu, PL
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電子工程學系及電子研究所
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電控工程研究所
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Department of Electronics Engineering and Institute of Electronics
This paper proposes a robust proportional-integral (PI) controller design for multivariable complex processes to achieve both well-decoupled and well-damped output behavior. By reformulating PI-controlled processes in a way similar to the LQG/LTR control design problem; the proposed model matching technique in the first design stage successfully results in the robust PI controller with well-decoupled output behavior and sufficient stability. Moreover, control performance can be further improved to achieve well-damped responses by applying gain modification in a second design stage. Both simulated results using chemical processes and experimental results using a wind tunnel have proven the feasibility of the proposed PI controller design in real applications.
A practical design for a robust fault detection and isolation system
(1997-03-01)
Hwang, DS
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Chang, SK
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Hsu, PL
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電控工程研究所
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Institute of Electrical and Control Engineering
Based on a development for the unknown input observer (UIO) design, this paper presents a straightforward method of designing a robust fault detection and isolation (FDI) system for uncertain systems with unknown inputs. By exploiting the properties of a nominal model structure, we form a basic sec of residuals which is independent of the unknown input but is dependent on the measurements. Then, with this basic residual set, we append a dynamic weighting matrix to the residuals to increase the design freedom for meeting the required detection and isolation performance. Additionally, a generalized residual generator scheme (GRGS) is proposed to synthesize the parity relations for the isolation of faulty sensors in an uncertain system. The proposed strategy is verified through simulation studies performed on the control of a vertical take-off and landing (VTOL) aircraft in the vertical plane.
A systematic approach for the sequence controller design in manufacturing systems
(2005)
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
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.
Adaptive-feedrate interpolation for parametric curves with a confined chord error
(2002-03-01)
Yeh, SS
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Hsu, PL
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電控工程研究所
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Institute of Electrical and Control Engineering
Recently, modern manufacturing systems have been designed which can machine arbitrary parametric curves while greatly reducing data communication between CAD/CAM and CNC systems. However, a constant feedrate and chord accuracy between two interpolated points along parametric curves are generally difficult to achieve due to the non-uniform map between curves and parameters. A speed-con trolled interpolation algorithm with an adaptive feedrate is proposed in this paper. Since the chord error in interpolation depends on the curve speed and the radius of curvature, the feedrate in the proposed algorithm is automatically adjusted so that a specified limit on the chord error is met. Both simulation and experimental results for non-uniform rational B-spline (NURBS) examples are provided to verify the feasibility and precision of the proposed interpolation algorithm. (C) 2001 Elsevier Science Ltd. All rights reserved.
An application of Petri nets to supervisory control for human-computer interactive systems
(2005-10-01)
Lee, JS
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Zhou, MC
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Hsu, PL
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電控工程研究所
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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
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Hsu, PL
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電控工程研究所
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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
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Hsu, PL
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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 intelligent supervision system for the ion implementation in IC fabrication processes
(1998)
Shen, LC
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Hsu, PL
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper presents a real-time intelligent supervision system for IC ion implantation processes. A hardware interface is developed to directly extract the features from the 2-D analog image signals of a beam map. A qualitative model for the beam scanning is then obtained and the symptoms of abnormal operations can be analyzed to achieve on-line diagnosis. Furthermore, a fuzzy expert system is developed to advise operators taking appropriate adjustment for the beam scanning. This supervisory system has been implemented on Eaten NV-6200 A/AV ion implanters at the Taiwan Semiconductor Manufacturing Company. Copyright (C) 1998 IFAC.
An intelligent supervisory system for ion implantation in IC fabrication processes
(1999-02-01)
Shen, LC
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Hsu, PL
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電控工程研究所
;
Institute of Electrical and Control Engineering
This pager presents a real-time intelligent supervision system for IC ion implantation processes. A hardware interface is developed, to extract the features directly from the 2-D analog image signals of a beam map. A qualitative model for the beam scanning is then obtained, and the symptoms of abnormal operations can be analyzed to achieve on-line diagnosis. Furthermore, a fuzzy expert system is developed to advise operators on making appropriate adjustments for the beam scanning. This supervisory system has been implemented on Eaten NV-6200 A/AV ion implanters at the Taiwan Semiconductor Manufacturing Company. (C) 1999 Elsevier Science Ltd. All rights reserved.
An object-oriented design of the hybrid controller for automated vehicles in an AHS
(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
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.
An optimal and adaptive design of the feedforward motion controller
(1999-12-01)
Yeh, SS
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Hsu, PL
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電控工程研究所
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Institute of Electrical and Control Engineering
The zero phase error tracking controller (ZPETC) in motion control, as proposed by Tomizuka et at, renders the desirable zero phase error, but with a limited gain response, Moreover, a ZPETC, which is basically in a feedforward control structure, is very sensitive to modeling error, To improve the tracking accuracy of the ZPETC, this paper presents an optimal ZPETC design with a concise polynomial digital prefilter (DPF), The parameters of this well-designed DPF are obtained through the derived L-2-norm optimization. By cascading the developed DPF to the ZPETC, the resultant optimal ZPETC greatly improves the bandwidth of the tracking control systems while maintaining the zero phase error. Compared with other optimal approaches, the present design leads to much simpler procedures and fewer computations. Furthermore, the proposed optimal ZPETC can be adequately implemented as an adaptive ZPETC by including real-time estimation technique to cope with the external load perturbation and parameter variation, Compared with the other adaptive approaches, the optimal concept is used in the present adaptive ZPETC; and it also renders more accurate results because of its improved magnitude response. Experimental results on a de servo table with different controllers indicate that when there is no loading, the present optimal ZPETC achieves the best tracking performance. Moreover, the adaptive ZPETC achieves the most satisfactory results when an external load is applied.
Analysis and design of integrated control for multi-axis motion systems
(2003-05-01)
Yeh, SS
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Hsu, PL
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電控工程研究所
;
Institute of Electrical and Control Engineering
In modem manufacturing, the design of multi-axis motion controllers for high-speed/high-precision and complex machining is becoming more critical. In the past, controllers for each axis were, in general, designed individually to obtain desirable tracking accuracy. Although some advanced motion control algorithms have been developed recently, they are mostly applicable to single-axis or biaxial systems. In particular, the design of two-axis integrated control, which includes: 1) feedback loops; 2) feedforward loops; and 3) the cross-coupled control (CCC), achieves significantly improved performance. However, its applications are limited to basic linear and circular contour commands for two-axis systems only. In this paper, system analysis for the multi-axis integrated control structure is proposed in order to achieve tracking and contouring accuracy simultaneously. With the derived contouring error transfer function (CETF), the integrated control design for multi-axis motion systems can be formulated simply as a single-input-single-output (SISO) design. Thus, a robust design with desirable performance for multi-axis motion systems can then be achieved straightforwardly. Moreover, by estimating the contouring error vector, the proposed multi-axis integrated control can be widely applied to general contour commands. Experimental results on a three-axis CNC machining center indicate that both tracking,and contouring accuracy are simultaneously improved by applying the proposed control design.
Analysis and design of the integrated controller for precise motion systems
(1999-11-01)
Yeh, SS
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Hsu, PL
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電控工程研究所
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Institute of Electrical and Control Engineering
Recently, feedforward controllers like zero phase error tracking controllers (ZPETC's) and cross-coupled controllers (CCC's) have been developed to effectively reduce tracking error and contouring error, respectively. This paper proposes an integrated controller which combines ZPETC and CCC to achieve both tracking and contouring accuracy. Furthermore, studies indicate that ZPETC and CCC can be designed separately in the present integrated control design, In the provided experimental setup with a servo table, an optimal ZPETC and a robust CCC based on the contouring error transfer function (CETF) were designed to achieve desirable frequency responses and stability, Experimental results show that the proposed integrated controller renders significantly improved accuracy in both tracking and contouring.
Applications of a variable step size algorithm to QCEE adaptive IIR filters
(2000-01-01)
Hsu, PL
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Tsai, TY
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Lee, FC
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電控工程研究所
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Institute of Electrical and Control Engineering
The quadratic constraint equation error (QCEE) method was proposed by Ho and Chan to achieve bias removal for the equation error adaptive IIR filters. However, this approach is limited to slow convergence in estimation when a small step size is used; large step sizes Lead to significant misadjustment. This correspondence presents a variable step size (VSS) technique to greatly improve the QCEE under its quadratic constraint to achieve both fast convergence and reduced misadjustment for adaptive IIR filters.
CAN-based motion control design
(2003)
Hsieh, CC
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Wang, AP
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Hsu, PL
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電控工程研究所
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Institute of Electrical and Control Engineering
Applying the controller area network (CAN) bus, this paper proposes the integration of three advanced motion control designs: (1) the zero phase error tracking control (ZPETC) mainly for each individual axis in the multi-axis system, (2) the zero magnitude error tracking control (ZMETC) for each individual axis at the high speed in the multi-axis system and (3) the cross-coupled control (CCC) for multiple axes of the whole system. The ZPETC and CCC or ZMETC and CCC serve to improve tracking and contouring motion accuracy, respectively. Experimental results on two AC servomotors show significantly improved motion accuracy, demonstrate the feasibility of the proposed approach.
Design and implementation of the SNMP agents for remote monitoring and control via UML and Petri nets
(2004-03-01)
Lee, JS
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Hsu, PL
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電控工程研究所
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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.