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Date 14-16 June 1982

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Displaying Results 1 - 25 of 269
  • Proceedings of the 1982 American Control Conference

    Page(s): 1
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    Freely Available from IEEE
  • Copyright page

    Page(s): 2
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    Freely Available from IEEE
  • Sponsoring Organization

    Page(s): 3
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    Freely Available from IEEE
  • To the memory of our colleague: Richard V. Monlopoli

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    Freely Available from IEEE
  • ACC 1982 Program at a Glance

    Page(s): 5
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    Freely Available from IEEE
  • Table of contents and Program

    Page(s): 6 - 26
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    Freely Available from IEEE
  • Participant index

    Page(s): 27 - 30
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    Freely Available from IEEE
  • Foreword

    Page(s): 1
    Save to Project icon | Request Permissions | PDF file iconPDF (89 KB)  
    Freely Available from IEEE
  • Parameter Estimation and Control of Distributed Systems with Application to Large Deployable Antennae

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (665 KB)  

    This paper will examine the estimation and control of distributed parameter systems which have application to the shape control of a large deployable communications antenna (~100 meters in diameter). Such an antenna would be collapsed and carried into orbit by the NASA space shuttle. Once in orbit, the antenna would automatically deploy like a collapsable umbrella. The antenna surface would be quite flexible and its shape would be adjusted by several attached cords or stringers. After long periods of operation, the antenna surface would require refocusing due to changes in the elastic properties of structure and thermal loads. This fine-tuning would be accomplished by an on-line control system which would process sensor measurements at various locations on the structure to estimate the present antenna shape and then generate control commands to the stringers to bring the antenna back to the desired shape. This is an example of a quasi-static parameter estimation and control problem for a distributed parameter system. Procedures will be developed for synthesis of implementable (finite-dimensional) parameter estimation and control algorithms for this type of problem based on finite element structure analysis. View full abstract»

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  • Number, and Placement of Control System Actuators Considering Possible Failures

    Page(s): 7 - 15
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1288 KB)  

    One of the first questions facing the designer of the control system for a large space structure is how many components¿actuators and sensors¿to specify and where to locate them on the structure. This paper presents a methodology which is intended to assist the designer in this process with respect to actuators. A measure of controllability is defined which is a quantitative indication of how well the system can be controlled with a given set of actuators. Then the effect of component unreliability is introduced by computing the average expected Degree of Controllability over the operating lifetime of the system accounting for the likelihood of various combinations of component failures. The problem of component location is resolved by optimizing this performance measure over the admissible set of actuator locations. The variation of this optimized performance measure with number of actuators is helpful in deciding how many components to use. View full abstract»

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  • Least-Squares Sequential Parameter and State Estimation for Large Space Structures

    Page(s): 16 - 21
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (571 KB)  

    This paper presents the formulation of simultaneous state and parameter estimation problems for flexible structures in terms of least-squares minimization problems. The approach combines an on-line order determination algorithm, with least-squares algorithms for finding estimates of modal approximation functions, modal amplitudes, and modal parameters. The approach combines previous results on separable nonlinear least squares estimation with a regression analysis formulation of the state estimation problem. The technique makes use of sequential Householder transformations. This allows for sequential accumulation of matrices required during the identification process. The technique is used to identify the modal parameters of a flexible beam. View full abstract»

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  • On the Selection of Optimal Bandwidths for LSS Controllers

    Page(s): 22
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (131 KB)  

    It has been established that any linear dynamical feedback controller (complete with model errors) will not destabilize a stable physical plant if the controller gain is "small" enough. It has also been established that any linear dynamical feedback controller will always destabilize the physical plant if the gains are "large" enough. The first result follows naturally from the laws of continuity. The latter result can be explained as the consequence of "modeling errors" That is, no mathematical model (upon which the controller is based) exactly describes any physical process. Hence, there are always modeling errors, and their significance depends upon the magnitude of the controller gains. The larger gains eventually cause the controller spectrum to exceed that spectrum for which the model is credible. In general terms then, the obvious conclusion is that there is a "best" gain in the sense that a smaller gain would yield degraded performance due to failure to exploit known model structure, and a larger gain would yield degraded performance due to the effects of modeling errors. In application to Large Space Structures this means that there exists a "best" set of gains associated with a controller of specified dimension. Furthermore, these gains cannot be determined from knowlege of the reduced model alone. View full abstract»

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  • Bifurcation and Limit Cycle Analysis of Nonlinear Systems with an Application to Aircraft at High Angles of Attack

    Page(s): 23 - 27
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (742 KB)  

    A new approach is presented for analyzing nonlinear and high-¿ dynamic behavior and stability of aircraft. This approach involves the application of bifurcation analysis and catastrophe theory methodology to specific phenomena such as stall, departure, spin entry, flat and steep spin, nose slice, and wing rock. Quantitative results of a global nature are generated using numerical techniques based on parametric continuation. We discuss how our methodology provides a complete representation of the aircraft equilibrium and bifurcation surfaces in the state-control space, using a rigid body model with aerodynamic controls. Also presented is a particularly useful extension of continuation methods to the detection and stability analysis of stable attracting orbits (limit cycles). The use of this methodology for understanding high-¿ phenomena, especially spin-related behavior, is discussed. View full abstract»

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  • Dynamic Analysis of the Electrostatically Controlled Membrane Mirror using Multiple Scales

    Page(s): 28 - 33
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (690 KB)  

    The vibrational dynamics of an electrostatically controlled membrane mirror are investigated. The motion is described by a nonlinear partial differential equation with nonconstant coefficients. The system equation is first linearized and then parameterized. The resulting equation is a singularly perturbed linear partial differential equation with variable coefficients. Asymptotic approximations are then developed systematically by the generalized multiple scales method. Thus, the rapid and slow aspects of the membrane dynamics in both the spatial and temporal sense are separated systematically. The results of our approach are compared with direct numerical integration. An excellent agreement between the two solutions is seen in the comparisons. Further reduction of the errors by including higher order approximations is discussed. View full abstract»

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  • The Janet/Busch Oscillator: A Multivibratory Dissipative Structure Relevant to Dynamo Theories of Geomagnetic Flux Reversals

    Page(s): 34 - 39
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (615 KB)  

    A dynamo model of geomagnetism displaying multivibratory flux reversals is presented. This model employs a little-known but century-old motor/ generator system; it can be obtained from Bullard's original series dynamo model by replacing his short-circuit with a virtual loaded capacitor, realized by a separately-excited motor. This resulting system furnishes a dissipative structure whose symmetry-breaking instability corresponds precisely to that of the Rayleigh/Van der Pol relaxation oscillator. Motor field strength determines the vibratory frequency. If the field varies, so does the frequency, yielding an infinite reversal period for a field becoming sufficiently weak. View full abstract»

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  • Conversion of Existing Continuous Control Systems into Digital Control Systems

    Page(s): 46 - 51
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (606 KB)  

    The problem of converting existing continuous data control systems into digital control systems is considered. The objective of this paper is to develop a computer-aided method for synthesizing the pulse-transfer function of the digital controller. This is done by matching the frequency response of the digital control system to that of the continuous system with a minimum weighted mean square error. Formulas for computing the parameters of the digital controller are obtained as a result. The design technique is illustrated with a numerical example and a comparison with previous methods is also presented. View full abstract»

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  • On Choice of the Quantization Interval in Stochastic Control Systems

    Page(s): 52 - 56
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (506 KB)  

    The paper is concerned with choice of time intervals between measurements of output coordinates and generations of control signals in control systems for stochastic discontinuous plants. View full abstract»

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  • A Z-Domain Controller Design Method for Sampled-Data Systems Having Feedback Dynamics

    Page(s): 57 - 59
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    A design method for sampled-data systems having dynamics in the (single) feedback path is described. The method is an alternative to such well-known methods as those of Ragazzini, Dablin, and Kalman in which feedback dynamics are difficult to handle. With the method described here, the designer has substantial flexibility in specifying the closed-loop transfer tunction and is guaranteed a stable controller for a wide class of systems. The method is described and an application example presented. View full abstract»

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  • Bridging the Gap between Data Acquition, Probe Control and Data Reduction, using a Microcomputer System

    Page(s): 60 - 62
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2635 KB)  

    This paper describes a microprocessor-controlled data-acquisition and data reduction system for large scale engineering tests. The microcomputer also controls automatic testing probe positioning, and furnishes the opportunity for generating an engineering report via word processing. The micro-computer has been interfaced with off-the-shelf type step motors to move the probes to the desired locations in the measurement area. The analog signals received from various transducers were digitized, stored, reduced and analyzed in real time. The system further proved its versatility by providing facility monitoring information to the operator and word processing capabilities to generate the final report. The computer system is fully operational in an aerodynamic flow test facility, and has conducted tests on a scale model gas turbine, and heat recovery steam generator (HRSG). The complete system has been brought together, using relatively inexpensive, readily available hardware. The system resulted in considerable time and manpower savings in conducting the test. View full abstract»

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  • Look-Ahead Digital Control of Single-Input, Single-Output Linear Systems

    Page(s): 63 - 68
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (547 KB)  

    Look-ahead or preview control is possible where future knowledge of system inputs is available. Designs based on look-ahead control can result in significant improvements in performance In this paper, a systematic development is given for deterministic look-ahead digital control of single-input, single-output linear systems. View full abstract»

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  • Finite Settling-Time Controllers from the Process Transfer Matrix

    Page(s): 71 - 72
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (235 KB)  

    In control literature a variety of deadbeat control algorithms is presented. In this paper a realization will be presented that is very well suited for process control. For a number of situations (unstable processes, nonminimum phase behaviour) elegant algorithms will be derived. The computation of the algorithms from the process transfer matrix is straightforward. The use of the algorithms will be demonstrated on the control of feed flow disturbances in a distillation column. View full abstract»

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  • Computing the Relative Gains for Pressure and Composition Control of a Single Distillation Tower

    Page(s): 74 - 80
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (915 KB)  

    This paper treats calculation of the steady-state relative gains for controlling a single distillation tower. A detailed mathematical model is formulated and solved by a modified Wang and Henke method. Three columns of 90%-10%, 95%-5%, and 99%-1% end product compositions for a benzene-toluene system are considered. The computational results show that the size of the perturbation used to calculate the partial derivatives for the relative gain and the convergence tolerance should be smaller for high purity columns than for low purity columns. Two consistency tests of the computational results are also presented. View full abstract»

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