P. Townsend

Open architecture for computer-aided control engineering

Some guiding principles for the design of open systems suitable for computer-aided control engineering are presented. Some possible architectures are considered, and an assessment is made of the available technologies that might be suitable for an open environment. An analogy is made with the requirements for computer-aided software engineering, for which a reference model has already been developed. It is concluded that such a model might well provide a clear definition of what is needed in computer-aided control engineering.<<ETX>>

A graphical pre-processor for computer-aided control system design

Features in the design of a graphical man-machine interface for pre-processing the inputs to computer-aided control system design software are described in this paper. The primary objective is to allow the control engineer to communicate with a modem graphics workstation in a natural, familiar and friendly way, by means of block diagrams, signal flow graphs and standard mathematical text. Graphical methods for the input and output of these are described. Transformations between different system descriptions are considered which allow all algebraic manipulations and reductions to be performed on signal flow graphs. For these manipulations, rule-based methods are shown to be effective. The possibility of using symbolic computation languages for algebraic operations is also considered.

Algorithms for Transformations Between Block Diagrams and Signal Flow Graphs

Abstract Several aspects of handling block diagram and signal flow graph representations of systems in a graphical pre-processor for the computer-aided design of control systems are considered in the paper. Both matrix and rule-based methods for implementing these forms of system representation, and for transforming one form into the other, are described, and it is concluded that the rule-based methods show considerable benefits and promise for future developments, which include an automatic layout tool for post-processing the output of the transformation algorithms.

The Making of Exces - A Software Engineering Perspective

Abstract This paper is concerned with the software engineering aspects of the development of eXCeS (Extended X-based Control Engineering workStation) - an integrated computer-aided design environment for control engineering. The requirements of such an environment are analysed and major implementation issues including modularised infrastructure, standard ‘look and feel’ and uniform and extensible data environment are discussed. The eXCeS environment takes account of each of these issues in order to provide a user interface which meets the needs of control engineers, incorporates the latest developments in user interface technology and provides a platform for a wide spectrum of software products for computer-aided control system design.

An approach to project management in computer-aided control engineering

Abstract An integrated approach to the management of computer-aided control engineering projects is described. It is shown that to exploit the benefits of object-oriented modelling and design an object-oriented database is required. A dynamic system object model is developed for use in project management using an object-oriented database. A complete description of the project management facilities is given, and the graphical user interface is described. A case study is used for illustration. Open architectures are considered and it is concluded that, together with object-oriented methods, these provide the possibility for exploiting the work described.

A Reference Model for Computer-aided Control Engineering

Abstract A reference model for computer-aided control engineering is developed from a reference model for computer-aided software engineering environments. It comprises a framework, with user intelface, database, message, task management and modelling service groups, and a set of tools. Three groups are similar to those in the computer-aided software engineering model, for which layered models have been developed. The task management and modelling service groups are more closely related to the requirements of computer-aided control engineering. Adoption of the reference model is advocated to initiate the development of an Open System for computer-aided control engineering.

Symbolic mathematics in control system analysis and design

Symbolic mathematical techniques and computer algebra systems have yet to be widely applied within the field of control. The benefits they have to offer in terms of greater accuracy and clarity of solutions for system analysis and design have yet to be fully exploited. This paper discusses these benefits and the facilities required by the user to support the use of symbolic algorithms and computer algebra systems for analysis of dynamic systems. These facilities include the means to store, edit and manipulate symbolic mathematical representations of the properties of a system. The methods by which this data may be used for analytical investigation by both symbolic and numerical packages are discussed. Finally, an implementation of such facilities within an integrated graphical environment for control engineering is described.

The Impact of Recent Developments in User-interface Specification, Design and Management on the Computer-aided Design of Control Systems

Abstract This paper describes the characteristics of advanced graphical user interfaces for the computer-aided design of control systems which can be developed using modem windowing environments. The significance of the emergence of windowing standards, such as the X Window System, and of user-interface standards, such as OPEN LOOK, is discussed. The increasing imponance of object-oriented programming for the development and maintenance of these sophisticated user interfaces is noted, and the need for an object-oriented database for the support of the design process is identified. Examples are given of the advantages for control system design of being able to deploy a number of graphical tools simultaneously in a multi-window environment

CES - A Workstation Environment for Computer-aided Design in Control Systems

Abstract This paper describes CES, a Control Engineering workStation which provides an integrated graphical environment for the computer-aided design of control systems. CES provides user-friendly tools for the pre-processing of input information in graphical form, together with facilities for accessing existing packages for the computer-aided design of control systems. Tools for the input of graphical representations of systems in the form of block diagrams and signal flow graphs are described, together with facilities for the input of associated mathematical text in natural form. Tools for the symbolic reduction of a graphical representation, transformations between one type of graphical representation and another and for the automatic layout of graphical representations from topological data are also described. The requirements for interfacing CES to software packages for the computer-aided design of control systems are discussed.

The Manipulation of Graphical and Symbolic Models of Dynamic Systems

Abstract The development of an integrated Computer Aided Control System Design environment for use with a graphics workstation is described. This paper concentrates on the man-machine interaction aspects of the environment and the facilities for the input anu manipulation of dynamic system descripuons in graphical form with symbolic mathematical data. The graphical editors for the input of dynamic system topology, in block diagram or signal flow graph form, and the layout algorithms necessary for the fully automatic generation of these representations are described in detail. The facilities for the input and editing of the mathematical data, in standard mathematical form, and the algorithms for the manipulation of both this and the topological data of a system, using the logic programming language Prolog, are also described.