C.P. Jobling

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>>

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 object-oriented information model for computer-aided control engineering☆

Abstract The aim of modern computer-aided engineering research is to create integrated sets of tools that support all stages of the control-systems design life-cycle. The most efficient way to achieve the exchange of data between the tools of the integrated environment is to define an information model that is shared by all tools and maintained by a common software environment. An object-oriented information model for life-cycle support of computer-aided control engineering is presented in this paper, and a possible architecture for its implementation is suggested. The model has been formally specified in the information modelling language EXPRESS. Object-oriented methods are also to be used for database support and inter-tool communications. The design is evaluated against previously published information models for computer-aided control engineering.

Use of a prototype CACE integration framework based on the unified information model

Individual CACSD tools offer specialised functionality to the tool users. Within the context of a CACSD design, however, the need for additional project-related functionality arises. One such task involves the exchange of information between different tools without user involvement in the process. Also, keeping track of a projects steps is a desired quality for the environment. Neither of the two requirements can be directly attributed to the responsibility of any CACSD tool. An integrated CACE environment provides a solution to both problems by supplying additional communication and storage services to the CACSD tools integrated in the environment. This paper presents the operation of a prototype CACE environment which has been based on the unified information model, an information model which records the data structures involved in the complete CACSD life cycle. The environments services are explored and their contribution to assisting the engineers task is outlined.

Building Better Graphical User Interfaces for CACSD - The Case for Object-Oriented Programming

Abstract Graphical user interfaces are becoming the de facto standard for all kinds of applications on computers that range from IBM-PC compatibles to super workstations. Graphical user interfaces are. however, notoriously difficult to create. In this paper we review the changing expectations of computer users which are a direct result of developments in computer graphics. The support for these changing requirements that are provided by the current standards are discussed and finally the development of object-oriented programming and its relationship to graphical user interfaces are presented. The conclusions discuss the potential benefits that the new programming methodology provides for the development of future interfaces for CACSD systems.

Towards a “Repository Service” for Computer-Aided Control Engineering

Abstract The integration of tools within a computer-aided control engineering environment has been the topic of research for many years. In much of this previous work, a database has been placed at the centre of the proposed designs. By examining the whole lifecycle of control systems design, a unified information model has been developed which allows tools to exchange information between any stage in the design process. The information model is used as the basis for a prototype information repository service for an integrated computer-aided control engineering environment. Use is made of the EXPRESS information modelling language to formally specify the data objects to be stored in the repository and in software wrappers that allow existing tools to make use of the information. Examples of use of the repository and directions for further work are given.

A project based environment for computer-aided control engineering

Probably the largest single factor inhibiting the development of an environment supporting the full control engineering design cycle has been the lack of widely recognised standards in this field. The issue of standardisation can be viewed on two levels, the representation of the dynamic system model itself and the provision of database facilities, including those high-level facilities required for model management. This paper concentrates on the latter, examines the requirements of the user in this respect and describes a user interface to meet these requirements. The impact of current initiatives in open architecture development on future computer-aided control engineering software development is examined.<<ETX>>

Object-Oriented Programming and the Implementation of a Block Diagram Editor for the Macintosh

Abstract A block diagram editor has been developed for the Macintosh personal computer from a specification developed for a general graphical human-computer interface for an extended X-based Control Engineering workstation (eXCeS). It was implemented using THINK C. a version of C with object-oriented extensions that has been specially developed to provide case of programming for graphics based applications in the Macintosh environment. Our experiences are reported on using this programming environment for this application and details are given of its design and implementation. We also comment on the applicability of the object oriented paradigm for the development of Computer-Aided Control Systems Design (CACSD) tools.

TOWARDS A DOCUMENT CENTRED COMPUTER-AIDED CONTROL SYSTEM DESIGN ENVIRONMENT

Abstract Most conventional design processes produce documentation as a by-product: design is done within an environment or collection of tools and the design outputs, models, diagrams, results, etc are gathered together along with commentary (usually with hindsight) into some kind of document at the end of the process. Inspired by ideas taken from literate programming and notebook interfaces to design tools, a prototype document centred design document has been developed. In such an environment, the document is the main product and the design is a by-product of documenting the design. By implementing the framework components of the system in Java and by using the extended markup language (XML) to encode the contents of the documents, the system is made platform neutral and therefore portable. An example document centred environment for computer-aided control system design (CACSD), that integrates Matlab and Simulink with the document-based framework, is briefly described and indications for future possibilities for this technology are given.

Implementation issues of a unified information model-based CACE integrated environment

The creation of an open CACE integrated environment presupposes the existence of standardised mechanisms which equip the environment with enough flexibility for incorporating as wide a range of tools as possible. This paper discusses the central mechanism for the exchange of information between various tools integrated in a prototype CACE environment based on the unified information model. Details of the data communication mechanism and how it has been implemented for a range of diverse tools are discussed. The impact to the user of the existence of this mechanism is considered, and its main merits, from an implementation point of view, are explained.