Basic Control Structures Research Articles

Study of Accuracy of Inertial Stabilization System. 1st Report. Comparison of Characteristics of Stable Platform and Strapdown Schemes.

The characteristics of two control schemes for inertial stabilization, stable platform and strapdown, are investigated, based primarily on the analysis of their transfer functions. Since the basic control structures of stable platform and strapdown schemes to suppress disturbed body motion are feedback and feedforward, respectiveiy, sensor imperfection such as limited bandwidth and transport delay affects very differently to the two schemes ; stability decrease for the stable platform scheme and error increase for the strapdown scheme. Flexibility affects also differently for the two schemes. A couple of design criteria for the tradeoff of the schemes are derived, and are illustrated by numerical examples.

Model Reference Adaptive Control-Some Development Trends

The aim of the work is to present the state-of-the-art in this filed of adaptive control. Some development trends based especially on the general stability theory are analyzed. The characteristics of basic model reference adaptive control (MRAC) structures and algorithms are given in order to provide an insight into the development of the theory and to indicate the possibilities of their practical application. As the paper makes only a survey of the subject area, the stability proofs of the presented algorithms are omitted. The plant to be controlled is assumed to be described by a linear model.

On testable object-oriented programming

A new philosophy contributing towards the design of testable object-oriented ( OO ) software is introduced in this paper. The testing of conventional OO software focuses on the generation of tests for existing objects and systems; the testable object-oriented programming ( TOOP ) method draws attention to building testabilities into objects and systems during coding or compiling, so that the succeeding processes in test generation and implementation can be simplified. A new method of TOOP is developed to improve the testability of OO software. Software testability at object level and system level is quantitatively modelled. A set of fundamental built-in testable mechanisms oriented to the basic control structures in objects is constructed in order to improve the testability of OO software in terms of test controllability and observability. The most interesting feature obtained by TOOP is that the built-in tests in any objects can be inherited and reused in the same way as that of codes or functions in conventional OO software.

Entwurf und DSP-Implementierung von Fuzzy-Reglern f�r Servomotoren

This is the first paper to discuss the design and implementation of multiple fuzzy logic controllers in servo drives. Both ac and dc drives are considered since both types are used in high performance applications and their basic control structures are similar. The progressive development of single and multiple fuzzy logic controllers and detailed simulation and experimental results are presented for servo drives incorporating interacting fuzzy controllers. For the dc drive considered, the controllers are a speed controller, an armature current controller and a flux (field current) controller. In the case of the fully digital ac drive, a fuzzy speed controller is implemented in real time using the TI TMS320C30 DSP and is shown to provide stable, robust control. The design procedures and the drive responses are compared to those for conventional non-adaptive and self-tuning controllers. The advantages of a fuzzy approach to the design of variable speed drive systems are also discussed together with practical considerations for implementation.

A simple on-line adaption for indirect field orientation of an induction machine

Three simple methods of adapting for rotor time constant changes of an indirect field-oriented induction machine are proposed. These methods utilize voltages as field-oriented reference models in the basic model reference adaptive control (MRAC) structure. Each of these methods offers some implementation or performance advantage over previously proposed MRAC methods and other adaption techniques. The proposed methods are analyzed along with other previously proposed MRAC methods, and the advantages and limitations of each are discussed. Experimental results are presented for the proposed methods with the most advantages. >

A programming language for engineering computations

C-Map was initially developed for computer-aided instruction in structural analysis and design; however, its present capability extends far beyond, to cover a broad spectrum of numerical methods for engineering computations ranging from elementary calculus to nonlinear constrained optimization problems. The flexibility and power of C-Map derive from the technique of recursive nesting of functions which releases the power of previously isolated, yet robust, algorithms. Such capability far surpasses that of the most comprehensive collection of FORTRAN scientific subroutine package. C-Map comprises four integrated components: (i) a full-screen text editor with multiple stacked windows for simultaneous editing of programs and output files; (ii) a simplified C-like programming language with the basic control structures do-while, while, for, if/else, recursive functions, math library, built-in functions for advanced engineering computations including matrix operations for structural analysis; (iii) an interactive expression evaluator; and (iii) a simple authoring system with automatic cross-referencing of key-words. The program's versatility helps to meet the different needs of users at different stage of learning. A beginner may use only the built-in functions for math and matrix operations to get immediate, useful results; and the advanced users may write their own functions for more complex problems. This paper discusses the features of C-Map and its applications in teaching structural engineering.

Design of Active Noise Control Systems Operating in Three-Dimensional Non-Dispersive Propagation Medium

A coherent method for the design of active noise control (ANC)systems operating in a three-dimensional non-dispersive propagation medium (acoustic free field) is presented. An analysis of the basic control structures is provided and conditions for the robust operation of such systems are determined. Finally, these conditions are interpreted as constraints on the geometric compositions of the ANC system.

Rigorous dynamics and feedforward control design for distillation processes

AbstractFeedforward control has the theoretical potential for perfect control; therefore, research to simplify and improve the use of such a control strategy for possible industrial applications has potential value. A general model for simulation of controlled distillation columns is used to reproduce operating trends of some monitored variables for an industrial column. Comparisons between simulated and operating data show a general good agreement.When a rigorous model is available and can be proved reliable for practical purposes, the design of feedforward control schemes becomes viable and can be incorporated in the more conventional approach. A specific industrial example shows the practical implementation problems and the real economic value of a feedforward control strategy to optimize the process behavior. In particular, the feedforward control action can reduce the inherent error from changes in feed composition when a basic feedback control structure is used to infer composition.

Computer control of robotic manipulators using predictors

Model-based robot control algorithms require the on-line evaluation of robot dynamics, leading to hybrid continuous/discrete-time implementations. The performance of these fixed-gain control algorithms varies in the workspace and it is not adequate for trajectory-tracking. In this paper, we present a coherent discrete-time framework for the analysis of model-based algorithms and introduce predictors to compensate for modeling and discretization errors. The basic controller structure is not altered; an added supervisory module is proposed to monitor performance and adjust the command signal accordingly. The module injects a degree of adaptiveness in the controller and reduces the sensitivity of the design to unmodeled dynamics. Our preliminary simulation experiments confirm that one-step-ahead predictors lead to a more uniform performance and are suitable for trajectory-tracking applications.

A Framework for Modeling Programming Knowledge

Programming Concepts. To build a knowledge base that captures the programmer's expertise, we first of all have to investigate the concepts and relations in the programming domain. The standard literature on programming presents concrete programming constructs and explains how these are used in solving concrete problems. But just like playing a good game of chess requires much more than knowing the rules of the game, writing a good program requires much more than knowing the syntax and semantics of the basic building blocks in a particular programming language. The novice programmer views a program as constructed out of the standard data types, primitive operations, and basic control structures available in a specific programming language such as number, list, sum, append, and the if-then-else construct. The expert programmer reasons with larger and less language-specific abstract programming concepts. He views a program as a configuration of larger units of data and computation. Typical examples of such units are abstract data types like sets, sequences and graphs, abstract operators like filter and select, and control abstractions like dolorall Cognitive studies (De Groot 1965; Larkin 1980) confronting experts and novices in various technical domains indicate the existence and importance of abstraction level(s). They show that experts develop and use 'chunks' that correspond to functional units in their domain while non experts do not. The experts perform better in their domain because of these abstractions. The same results have been obtained in the programming domain (Eisenstadt 1985; Soloway 1984; Adelson 1981). Chunks or functional units of composed data and/or computation are from this point on referred to as abstract programming concepts. Abstract programming concepts help the programmer to deal with complexity. They summarise a stereotypical combination of more primitive programming concepts which is instantiated to solve a particular problem. On the one hand, the large expert vocabulary reflects the programmer's knowledge about the abstract concepts used in programming. On the other hand, the existence of this vocabulary indicates the importance of such abstractions in communicating and organising programming knowledge. Abstract programming concepts act as loci of programming knowledge and the relations between them introduce structure into the large body of programming knowledge.programming concepts help the programmer to deal with complexity. They summarise a stereotypical combination of more primitive programming concepts which is instantiated to solve a particular problem. On the one hand, the large expert vocabulary reflects the programmer's knowledge about the abstract concepts used in programming. On the other hand, the existence of this vocabulary indicates the importance of such abstractions in communicating and organising programming knowledge. Abstract programming concepts act as loci of programming knowledge and the relations between them introduce structure into the large body of programming knowledge. SEQUENCE is a structured collective data structure can be typed can be ordered if the element type has an order relation defined on it can be implemented as a linear-list, a vector, ... has element selectors defined on it such as first, last, nth, . has selectors defined on it such as filter, butfirst,

Sliding mode control of AC drives

The application of sliding mode control to permanent-magnet synchronous motors (DC brushless motors), wound-rotor synchronous motors, and asynchronous motors is presented. A unified approach to the control problem of AC machines reveals that a simple control algorithm which effectively solves the problem can be derived using variable-structure system theory. Selection of the control variable (angular position, speed, acceleration, or torque) leaves the basic control structure unchanged, and even current limiting can easily be included. The theoretical results are verified by experiments. The design procedure and experimental results show that this approach provides good behavior of the system in both transient and steady-state operation. >

A rigorous approach to structural analysis and metrication of software

The need is argued for a rigorous and general theory of structured programming as a basis for improving software quality. Formal graph theoretic methods are developed which allow the structural modelling, metrication and reconstruction of sequential programs in terms of precisely defined general sets of basic control structures. Throughout, concepts are illustrated by examples based on actual Basic and Pascal text.

One Robust, Dynamic Control Algorithm for Manipulation Systems

By digital simulation of an elementary functional movement for the manipulation system with six rotational degrees of freedom, a few dynamic control algorithms are investigated. The basic control structure consists of program (nominal) control and compensating term, which should provide for nominal trajectory tracking under initial-condition perturbations. As compensating control in the stage of perturbed regimes, the following were observed: (1) decentralized control, that is, local linear control law on the each actuator subsystem level; (2) suboptimal control, where the linear term is the same as local control, but "global" term takes into consideration the disturbance acting upon the subsystem as the result of coupling with other subsystems; (3) control law consisting of linear local control and nonlinear compensator, synthesized using Liapunov's second method. Those control laws are compared with respect to stability, tracking, energy consumption, and computational efficiency.

Some pedagogic considerations in teaching elementary programming using structured FORTRAN

This paper contains a description of several aspects of a course in introductory computer programming that is taught using a few basic control structure extensions to FORTRAN. The FORTRAN syntactic forms and flow diagram patterns of these structures are defined, and some of the advantages of these forms are listed. The problem solving methods developed in the course are outlined, and the structures are shown to be consistent with these methods. Some pedagogic considerations which provide an effective environment for the presentation of these control structures are described.

Some pedagogic considerations in teaching elementary programming using structured FORTRAN

This paper contains a description of several aspects of a course in introductory computer programming that is taught using a few basic control structure extensions to FORTRAN. The FORTRAN syntactic forms and flow diagram patterns of these structures are defined, and some of the advantages of these forms are listed. The problem solving methods developed in the course are outlined, and the structures are shown to be consistent with these methods. Some pedagogic considerations which provide an effective environment for the presentation of these control structures are described.

The 'natural' set of basic control structures

article The 'natural' set of basic control structures Share on Author: Johannes J. Martin State University, Blacksburg, Virginia State University, Blacksburg, VirginiaView Profile Authors Info & Claims ACM SIGPLAN NoticesVolume 8Issue 12December 1973 pp 5–14https://doi.org/10.1145/987006.987008Online:01 December 1973Publication History 12citation126DownloadsMetricsTotal Citations12Total Downloads126Last 12 Months2Last 6 weeks0 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

A Computing Machine Based on Tree Structures

The expenditure of resources to provide via software more structure and more function in conventional machines has become excessive. The answer to this problem may consist in providing more structure and more function in hardware. With respect to structure, we describe 1) the binary tree as basic data and control structure, 2) the implementation of a binary tree by a conventional memory, and 3) the associated hardware. The most important enhancement with respect to function, the newly introduced unit of action, deals with the handling of variables and substitution.