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Control Systems Technology, IEEE Transactions on

Issue 3 • Date Sep 1995

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Displaying Results 1 - 12 of 12
  • Submarine H depth control under wave disturbances

    Publication Year: 1995 , Page(s): 338 - 346
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    The depth control of submarines in the absence of wave disturbances (deep submergence) is a straightforward task, but at periscope depth the submarine-wave dynamics become very complex. To solve the submarine depth-keeping problem, a procedure for designing H controllers is proposed. This has been obtained by combining polynomial and state-space H methods. The polynomial approach allows the wave disturbances to be included in the design setting as design “parameters”. Reformulating the polynomial description in a state-space configuration enables the controller to be calculated using standard design software, e.g., the μ-toolbox of Matlab. The wave disturbances model, which may be considered to be formed of first-order (oscillating) and drift (second-order) components, is crucial in the proposed design procedure, as it becomes a design “parameter”. A successful representation of these disturbances is also included. The numerical problem caused by the ill conditioning of the standard interconnection system was solved by expressing the system in a “block observable” realization. The order of the controller was reduced by factorizing the common poles and zeros of the augmented plant. The criterion for selecting the cost-weighting functions is defined in terms of the dynamical system structure of the submarine. The success of the design procedure has been evaluated through a series of nonlinear simulations View full abstract»

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  • Fault detection and isolation for an experimental internal combustion engine via fuzzy identification

    Publication Year: 1995 , Page(s): 347 - 355
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    Certain engine faults can be detected and isolated by examining the pattern of deviations of engine signals from their nominal unfailed values. In this brief paper, we show how to construct a fuzzy identifier to estimate the engine signals necessary to calculate the deviation from nominal engine behavior, so that we may determine if the engine has certain actuator and sensor “calibration faults”. We compare the fuzzy identifier to a nonlinear ARMAX technique and provide experimental results showing the effectiveness of our fuzzy identification based failure detection and identification strategy View full abstract»

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  • Grafcet: a powerful tool for specification of logic controllers

    Publication Year: 1995 , Page(s): 253 - 268
    Cited by:  Papers (44)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1320 KB)  

    Basically, a logic controller is a discrete-event system whose purpose is to control the behavior of a process which is itself (seen by the controller as) a discrete-event system, taking into account the state of this process and other information coming from an operator or from other systems. In the early 1970s, the need to describe increasingly complex logic controllers was becoming evident, since the programmable logic controllers (PLC) were becoming more powerful and more extensively used. This paper shows how Grafcet can be used for this purpose. Grafcet is a tool, drawing its inspiration from Petri nets (a general purpose mathematical tool allowing various discrete-event systems to be described), whose aim is the specification of logic controllers. It is the basis of the sequential function chart (SFC), an International Standard in 1987. This paper, introductory in nature, explains the Grafcet model using the classical-state table model and presents a method for interpreting grafcets View full abstract»

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  • A modified relay-based technique for improved critical point estimation in process control

    Publication Year: 1995 , Page(s): 330 - 337
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    In this paper, we present a modified relay-based technique for estimating the critical point in process control systems with improved accuracy over existing relay-based methods. The proposed technique addresses the accuracy of the conventional approach by eliminating the errors introduced in the usual describing function analysis of nonlinear systems. The analytical basis of the technique is described in the paper, and it is also shown that it is theoretically possible to obtain an exact estimate of the process critical point under ideal conditions. The effectiveness of the proposed technique is verified by simulation results and also by real-time experimental results in the level control of a coupled-tanks system View full abstract»

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  • Nonlinear optimization-based design of ram velocity profiles for isothermal forging

    Publication Year: 1995 , Page(s): 269 - 278
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (900 KB)  

    The development of good material models, accurate nonlinear finite element codes, and computer-controlled presses make practical the application of control techniques to metal forging. This paper considers the open-loop problem of selecting a nominal ram velocity profile to produce a desired microstructure, given a specified die and preform geometry and forging temperature. Two approaches for doing so are applied to a simple, but representative problem. The first is based on classical numerical optimization techniques. The second is based on inverse neural networks and offers potential savings in critical computations. Simulation studies for the two methods show good results View full abstract»

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  • Performance enhancement of nonlinear drives by feedback linearization of linear-bilinear cascade models

    Publication Year: 1995 , Page(s): 299 - 308
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (888 KB)  

    Complex plants seldom fulfil the conditions required for the design of exact feedback linearizing controls. Using suitable approximate models, however, may allow the design of a feedback linearizing controller which, when applied to the true plant, leads to substantial performance enhancements provided the approximate model captures the essential characteristics of the plant. This paper discusses this issue in the case of an industrial hydrostatic gear. A linear-bilinear cascade model approximation is proposed, and a control law is derived to force such an approximation to behave like the “nearest” linear system, A simple, easily implementable form is obtained. The relevance of the approach is shown both by experimental results and by simulation studies to assess the optimization potential as well as the error sensitivity of the method View full abstract»

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  • Robust redesign of power system damping controllers

    Publication Year: 1995 , Page(s): 290 - 298
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    This paper presents a model-matching robustness design procedure based on H-optimization theory for the robust redesign of nominal controllers. The approach directly uses a control law designed for the nominal operating condition and tunes the nominal control law to enhance the robustness with respect to the off-nominal operating conditions. The procedure is applied to the design of a power system stabilizer (PSS) for a single-machine infinite-bus system which has a range of possible operating conditions. The results show that the redesigned controller contains features similar to the nominal controller, but yet improves significantly the damping of the machine swing modes at the off-nominal conditions View full abstract»

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  • Dynamic deadtime estimation for velocity-dependent systems

    Publication Year: 1995 , Page(s): 362 - 363
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB)  

    A simple but rigorous method of estimating the velocity-dependent deadtime is presented and compared to a steady-state method View full abstract»

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  • A continuous fuzzy Petri net tool for intelligent process monitoring and control

    Publication Year: 1995 , Page(s): 318 - 329
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1068 KB)  

    This paper outlines the structure and implementational features of a new methodology for intelligent process control called continuous fuzzy Petri net (CFPN). This methodology integrates Petri nets, fuzzy logic, and real-time expert systems to produce a powerful tool for real-time process control. This tool has been applied to the monitoring of an oil refinery processing unit. The developed system can relieve the operator from monitoring sensor data information and allow him to concentrate on the higher level interpretation of the occurrence of events. Based on an object-oriented programming style, the paper discusses how the CFPN is constructed to provide a software support environment to aid process control engineering activities such as: system modeling, operational analysis, process monitoring, and control View full abstract»

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  • Application of identification in ℋ to lightly damped systems: two case studies

    Publication Year: 1995 , Page(s): 279 - 289
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (932 KB)  

    This paper presents an approach to the frequency domain identification of lightly damped systems. It is based on work in the area of identification in ℋ. The emphasis of this paper is on the application of the algorithms developed in the literature to two case studies. Results show that the algorithms for identification in ℋ are capable of producing good models for highly flexible systems View full abstract»

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  • An approximation approach of the standard clock method for general discrete-event simulation

    Publication Year: 1995 , Page(s): 309 - 317
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (816 KB)  

    The standard clock (SC) method is an efficient approach for discrete-event simulation. Its basic ideas are quite different from traditional approaches. SC has neither an event list nor event lifetimes, its applicability is limited, however, to exponential distributions and a class of nonexponential distributions. In this paper we provide an efficient approach to general distributions. Shifted exponential and hyperexponential distributions are used as second-order approximations to simulation input distributions. Numerical testing demonstrates that they serve as good approximations and preserve the advantages of SC. In addition, an nth order method is presented that provides arbitrarily good approximations. The idea of event insertion extends SC use to further applications and improves simulation efficiency on SIMD machines View full abstract»

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  • Robust command-to-line-of-sight guidance via variable-structure control

    Publication Year: 1995 , Page(s): 356 - 361
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    This paper addresses the nonlinear control problem of guiding a point defense missile toward the line-of-sight between a defending ship and a sea-skimming missile, variable-structure control theory is employed to solve the problem. The resulting guidance algorithm consists of a third-order sliding surface. It forces the missile to converge rapidly toward the line-of-sight, avoiding dangerous undershoots. We demonstrate that in the context of a realistic engagement scenario, the algorithm exhibits sufficient robustness margins View full abstract»

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