Computer-aided Control System Research Articles

An Improved Algorithm for Generalising Pseudodiagonalisation

The multivariable frequency domain design method is playing an increasingly important role in computer-aided control system design and it depends on achieving a diagonally-dominant system to complete the design with success. The pseudodomination proposed in this paper enables us to design dynamic compensator to improve the dominance of the compensated plant over an extended range of frequencies. The procedure arises from Hawkins's generalising pseudodiagonalisation in a number of directions; in particular, the calculation is reduced and some important messages that provide a real facilitation to the design can be easily gotten at in computational process. Three examples designed interactively by computer are included to illustrate the effectiveness of the improved algorithm.

An Integrated Environment for Computer Aided Control Systems Engineering

The engineering of software for Computer Aided Control Systems Engineering (CACSE) using the concept of software tools is discussed. A set of tools are presented which will provide an infrastructure upon which a fully integrated CACSE package could be readily built. Emphasis is placed on the man-machine interface. An input and an output translator are introduced, and the interaction between them is discussed. An action manager, to control the CACSE functions of a package is presented. The control of retained data within a package using a data manager tool is discussed.

Integra, an Input Translation Facility for Computer Aided Control Systems Engineering

A software tool for input translation called INTEGRA (INput of TExt and GRAphics) is presented. INTEGRA is able to translate a stream of mixed graphical and textural input. The acceptable input is defined by the applications developer using extended transition networks represented as graphs, which are entered and manipulated graphically. INTEGRA provides a means of controlling the fine detail and a method of abstracting away from it using nested graphs. A variety of interaction tools are supplied to the user including macro languages, synonyms, prompting, menus, help, walkthrough, tracing, and customising. INTEGRA provides for the future development of expert system based adaptive man machine interfaces

A Flexible Man-Machine Interface for CACSD Applications

In this paper a man-machine interface well suited for Computer Aided Control Systems Design (CACSD) is presented. We will start with presenting the general command-driven interface of IMPACT. an interactive CACSD-package presently implemented in the new programming language Ada. In particular. we will elaborate on its versatile macro concept (functions/procedures). The interface of IMPACT uses a syntax similar to that of Ada and is flexible enough for the algorithmic type of problems found in CACSD. A facility of concurrent sessions not unlike those found on many modern workstations is presented. Thereafter, the macro and session concepts are combined to form the “query” option. a feature intended to be used to guide the inexperienced user in a more controlled manner.

Computer Aided Control System Design for Power Generation Plant

The paper describes the development of a computer-aided modelling and control-system-design facility for power generation plant. This has been fully imple-mented on a laboratory model turbogenerator, and extensive tests have been conducted on full-scale plant. The system is based on a dedicated PDP 11-23 microcomputer, with background processing on a VAX 11-780 minicomputer, using specially-written software packages. Results obtained both in the laboratory and from site tests are presented.

Evaluation of Computer Systems for Control System Design

We will discuss and evaluate a number of different computer systems for computer-aided control system design, ranging from superminis (VAX) to microcomputers (IBM PC). This evaluation will deal with price, software support, calculation speed, memory size and graphical output facilities.

CAD in Control Engineering Education

The paper describes the role of software packages for computer-aided control system analysis and design (CACSAD) in, control engineering education. It is shown that CACSAD-systems are becoming an indispensible tool in education, because even sophisticated methods are more easily understood by the students. Realistic problems can be solved within reasonable time, especially the laboratory experiments. As an example of a CACSAD-package, the KEDDC-system developed by the author and his coworkers, is described. It is shown how the KEDDC-system is introduced into the education of control engineers at the electrical engineering department of Ruhr-University Bochum.

Computer-Aided Design of Spacecraft Control Systems

The KEDDC software package for computer-aided control system design, developed at Ruhr-University, Bochum, F. R. G. is presently applied by the Communications Research Centre (CRC), Ottawa, Canada to the development of control techniques for future large flexible spacecraft in a joint industry, university and government research and development project. The Operational Mobile Communications Satellite (OKSAT) proposed for the aid 1990's featuring a 44m offset-fed antenna, is used as target application. A reduced version of a 146th order high fidelity dynamics model of the satellite serves as a benchmark system. This application is very demanding and forms an important performance benchmark for any software system because the high order of structural models requires the use of highly stable and efficient numerical algorithms. KEDDC has been tested on this problem for more than one year and has performed flawlessly, improving quite considerably the design efficiency as well as the scope of system analysis.

Computer Aided Interactive Multiobjective Satisfaction and its Application to Control System Design

Abstract Recently, in the various kinds of design fields, such as mechanical design, computer aided design systems have been or are being developed actively. One of the main purposes is directed to the drawing techniques with graphic displays after the size of each element has already been determined. On the other hand, in most designs, the size of each element is determined by trial and error. It is considered that in the future, it will become more important to correct the size of each element or parameter systematically and efficiently and to set the adequate values using the man-machine interaction. Based on such ideas, we will consider the case that the mechanical design is formulated as a multiobjective optimal design problem, and various optimization methods can be applied in o-rder to determine the optimal design condition systematically and efficiently. In order to develop the useful method which decreases the load of the designer, Satisfaction may be considered instead of Optimization. In the former, a solution satisfying the permitted limit is searched for. In the actual design problem, the formulation of satisfaction is rather more spontaneous than that of optimization. Besides, in even the opposite case, because the preference and the ability of the decision-making of the designer usually include uncertinety, determining a satisfactory solution from within the bound set of solutions is rather more practical than determining a unique preference solution using optimization. Accordingly, a new satisfaction method is proposed for solving multiobjective satisfactory design problems. It is composed mainly of two ideas; the techniques for judging the existence of the solution satisfying the permitted limit, and the systematical setting and correcting of the value of the permitted limit based on interactive information with a designer. Compared with the other interactive methods in multiobjective optimization, in the proposed method the total amount of calculation and the iteration number of interaction can be decreased. Moreover, the load of a decision maker at each interaction may be decreased. These roles are usually borne by the non-professional designer in the mathematical programming area. This method is applied to a computer aided design of control system. In the model follow control method as one of the control system design techniques, the transfer functions of a control system can be coincided with transfer functions which are given in advance as desired ones using a certain procedure. Computer aided control system design using the model following control method is composed each of the decision process of the desired transfer functions and the decision process of the control system. The latter is composed of the desired transfer functions and the transfer functions of the actual plant are input and, as a result, a .controller is output. However, the decision process of the former has not been so clear until now, and it was necessary to determine the form of the desired transfer functions to satisfy the design specification with correcting its parameter by trial and error. If this process is aided by the proposed satisfaction method, the desired transfer functions can be determined systematically and efficiently. The decision process problem of the desired transfer functions is formulated by the following factors. As for the performance of the control system, the relative stability, the speed of response and the accuracy should be sythesized and assessed. The overshoot and setting time in the step response characteristic are taken as the factors for the relative stability; the rise time, delay time and band width in the frequency response characteristic for the speed of response; and the velocity constant for the accuracy, where the band width includes the meaning to decrease the influence of the noise. The proposed interactive method is applied to the actual systems in order to confirm its efficiency. The first example is a 60 000 ton tanker 219 m in the length, 32.2 m in width, and 6 m in the mean draught. The problem is formulated, the desired transfer functions are determined and the control system is constructed. The next example is the control system design for the refrigerating machine. This is a three input-three output system with interactions between variables, but for convenience sake this overall system is considered as three independent one input-one output subsystems. For the actual testing plant of a refrigerating machine, the problem is formulated and the desired transfer functions are decided using the proposed method.

Control systems computed

Computer-aided control system design, Institute of Measurement and Control and SERC, 19-21 September 1984, University of Sussex, Brighton.

Experiences in using a computer-aided control system design suite in an undergraduate Electronic Engineering degree course

The Hull computer-aided control system design suite has been used within the undergraduate Electronic Engineering degree course for over five years. The paper describes the facilities within the suite and the limitations imposed on its use by current hardware constraints. The suite is used in each of the final three years of the four-year course, starting with restricted laboratory access for the analysis of linear single-input single-output systems and progressing to free access to the nonlinear and multivariable design facilities. The integration of the use of the design suite with the rest of the coursework is discussed and evaluated. Further developments are outlined.

Numerical linear algebra aspects of control design computations

The interplay between recent results and methodologies in numerical linear algebra and mathematical software and their application to problems arising in systems, control, and estimation theory is discussed. The impact of finite precision, finite range arithmetic [including the implications of the proposed IEEE floating point standard(s)] on control design computations is illustrated with numerous examples as are pertinent remarks concerning numerical stability and conditioning. Basic tools from numerical linear algebra such as linear equations, linear least squares, eigenproblems, generalized eigenproblems, and singular value decomposition are then outlined. A selected list of applications of the basic tools then follows including algorithms for solution of problems such as matrix exponentials, frequency response, system balancing, and matrix Riccati equations. The implementation of such algorithms as robust mathematical software is then discussed. A number of issues are addressed including characteristics of reliable mathematical software, availability and evaluation, language implications (Fortran, Ada, etc.), and the overall role of mathematical software as a component of computer-aided control system design.

Computer Aided Control and Real Time Control Program Organizing System “CACOS”

Computer aided control and organizing system CACOS is presented, which assists on line real time control incorporations computer aided control system design and analysis program package. When a multivariable control system is designed, CACOS generates a real time control program RCOR automatically from the designed data, which is written in machine code and can run in real time with the floating point calculation. Thus this system makes it possible to design control system and to evaluate its performance simultaneously.

Computer Aided Control System Engineering

A systems engineering based methodology for control systems engineering will be presented. The need for such a methodology will be discussed. The methodology is presented within systems engineering design environment. Architectural and implementation aspects of computer aided problem solving tools for the support of the methodology are described. The architecture of that tools is a distributed open information processing system, the implementation is based on a service integrated local area computer network, that allows an incremental, flexible, extendable realization, a fact which is very important for small and medium sized companies

Graphical Input Facilities for Computer Aided Control System Design

The work to be described here presents a flexible graphical input facility allowing system descriptions in both block-diagram and signal-flow graph form to be readily input. Both single-input, single-output and multivariable system definitions of arbitrary structure are allowed, and various system properties between user nominated points in the system can be readily obtained. The improved flexibility provided by this facility should prove valuable in analyzing the sensitivity, robustness and integrity aspects of control systems design by a variety of methods. The use of the graphical input facility will be illustrated.

Environment and Methods for Robust Computer Aided Control Systems Design for Nonlinear Plants

A general software environment and a control system design approach for multivariable nonlinear plants are motivated and developed. The software environment recognizes the iterative nature of the design process and completely automates it; it is described in functional terms, as viewed by the control system designer. The design method is based on recent breakthroughs in describing function theory that uses a modern algebraic problem formulation to remove all previous nonlinear system restrictions: one may deal with plants having any number of nonlinearities, in any configuration, and of any type, including multiple input nonlinearities, and arrive at quasilinear models of the plant that will serve as a realistic basis for control system design.

Future directions in computer-aided control system design software development

Issues in the development of a new package of computer-aided control system design software are presented. The scope of the project is limited to the organization of existing results into a unified body of software, and the development of a standardized set of tools and services which allow long-term maintenance and growth of the package and support the user community. Issues which influence language selection, graphics requirements, core algorithm selection, model description requirements and software tools, and future hardware expectations are addressed.

Multivariable process control - A survey

A survey is provided of the state of the art in multivariable process control. Recent literature is organized and tabulated by topic to provide material for further study. The survey encompasses both linear and nonlinear multivariable systems, on-line estimation, adaptive control, distributed systems, and recent developments in computer-aided control system design. These developments together with recent applications provide the basis for predictions of the future evolution of the field.

Computer-aided control system analysis and design using interactive computer graphics

A variety of programs involving interactive computer graphics are available at Rensselaer Polytechnic Institute for the analysis and design of both univariable and multivariable control systems and for related instructional purposes. The principal features of these programs and the ways in which they are used in the curriculum are discussed.

Development of a software library and a interacrtive design and environment for computer-aided control system design

Development of a software library and a interacrtive design and environment for computer-aided control system design