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A practical approach to the design of control systems for strongly nonlinear, multivariable, time-dependent plants is described. The structure of the control system is that of an exact model follower. The model dynamics are decoupled, linear, constant, and of the order of the plant. The plant state and controls are transformed so that the plant, when viewed through these transformations, looks like...
Flutter phenomena associated with various store loadings on modern fighter aircraft wings are diverse and can severely inhibit performance. Passive means of suppressing flutter can be costly in terms of performance as well. Active flutter suppression is a potential means for overcoming these performance degradations. Adaptation is required to treat the diverse flutter phenomena. This application is...
A method is presented for generating diagnostic procedures from fault trees. Diagnostic procedures are directly constructed using the cause and effect relationships present in fault trees and the models on which the fault trees are based. The method provides flexibility in the depth of detail, identification of common causes of multiple events, and resolution of apparent multiple event inconsistencies...
An adaptive controller for a pressbrake has been designed, built and tested. The controller measures force and displacement during the early part of the bend cycle to estimate workpiece parameters. These parameters are used in an elastic-plastic material model to predict the correct final punch position to yield the desired unloaded angle. A microcomputer is used to control a Cincinnati CB90 hydraulic...
The problems of detection and identification of failures in process equipment, sensors, and actuators is addressed using some recent results from nonlinear filtering theory.
This paper demonstrates the application of a pattern recognition algorithm to ship classification problem. The algorithm, Recursive Structure Identification, or RESID, has several advantages over other pattern classification methods. RESID has the ability to examine a large number and variety of object features, reject those features containing little information about the object, and combine the...
A simple scale-invariant criterion is proposed for picking out state variables that 'significantly participate' in the construction of selected modes of a linear time-invariant dynamical system. The criterion is of value in such approaches to modal reduction as Davison's method, singular perturbation methods, and our 'Selective Modal Analysis' framework (which in several respects extends the former...
A computer model of a 200 MWe coal-fired MHD/steam power plant is being employed to predict the dynamic response of the plant. This model is based on first-principles relationships for fluid flow and heat transfer in the steam bottoming cycle. The control system model is similar to an integrated boiler/turbine control for a conventional fossil-fuel plant. Preliminary predictions of the response of...
A recursive least-squares estimator is developed in an identification observer format with the modification that the need for estimating initial conditions is eliminated. Estimators are developed that work with observed input/output data corrupted by deterministic, piece-wise deterministic, or stochastic noise. Results of numerical simulations are included.
The use of digital computers in the flight control system has introduced a new dimension in flexibility. Only within the last few years have the digital analysis and design tools been dusted off and sharpened to meet the needs of the modern, complex control system. This paper will outline the past, present, and future work the Flight Dynamics Laboratory has done in the area of digital design methodology...
A method is developed to evaluate the relationship between cost and performance in sensor system design. The conflicting requirements of minimizing cost and maximizing performance are met by a trade-off analysis. Sensor cost is set proportional to systematic precision (defined as the inverse of the systematic error variance), and system performance is chosen to be a measure of the Cramer-Rao lower...
A sufficiency condition for a periodic process with free period to be a weak local minimum is given. By making detailed use of the properties of the monodromy matrix, the transition matrix calculated over a closed orbit, previous results are corrected, extended and clarified. For example, a necessary condition for a real valued periodic Riccati matrix to exist is that there be no distint eigenvalues...
The use of local high-gain feedback to stabilize a class of nonlinear interconnected systems is studied. Classes of systems that can be stabilized, for any arbitrary interconnections, using only local high-gain feedback are identified.
This report summarize our experience in the process improvement and computer control implementation experience with several major international Olefin plants, it examines common pitfalls in all phases of computer control application: from economic incentive evaluation, control scope and objective definition, to process and control modeling, instrumentation and control computers specification, process...