As computer-controlled systems become ever larger and more complex, the difficulties of achieving performance objectives in the presence of disturbances and modeling uncertainties become ever more challenging. The multidisciplinary nature of modeling and simulation to achieve product and process understanding in diverse application areas such as discrete manufacturing, telecommunications, and missile guidance, navigation and control adds to the challenge. The control engineering community has been actively pursuing avenues for supporting multidisciplinary design activities for several years. Albert Benveniste led a joint effort to identify challenges of computer science in industrial applications of control. This effort and others has recognized the need for advances in control design environments, including support for hybrid systems. The US Army Research Office and the US Army Armaments Research, Development and Engineering Center have been supporting hybrid systems research for several years. One effort focused on improving support for large-scale systems and funded by the US Department of Defense has been the Domain-Specific Software Architectures (DSSA) project. The DSSA project seeks to improve coordination between disciplines and lower life-cycle costs of complex systems by (1) performing a task-decomposition of process activities associated with a particular product (or domain), (2) creating a reference architecture of typical software components associated with producing the product, and (3) providing tools and design processes for architecture-based reuse of design and implementation components during the product life-cycle. Three of the papers in this special issue (Bencze and Franklin, Englehart and Jackson, and Kohn et al.) describe efforts which were partially supported by the DSSA program.
The Computer-Aided Control System Design (CACSD) Technical Committee of the IEEE CSS and the Computer-Aided Design in Control Systems (CADCS) committee of the International Federation of Automatic Control (IFAC) sponsor activities which enable researchers to share technical results in the field of Computer-Aided Control Engineering (CACE). CACE is a specialized form of modeling and simulation with emphasis on modeling and simuldesign and implementation of feedback control systems. As control implementations grow in size and complexity, CACE tools assume a more important role in engineering design, implementation, and maintenance of computer-controlled devices. The papers in this special edition were selected from the proceedings of the first IEEE/IFAC Joint Symposium on CACSD, held in Tucson, Arizona in March, 1994. Copies of the proceedings are available from the IEEE press. Proceedings from previous meetings of the CACSD TC in 1986, 1989, and 1992 are also available as are proceedings of the CADCS meetings in 1985, 1988, and 1991. The next symposium of the CACSD TC will be held jointly with the IEEE TC on Intelligent Control and the IEEE TC on Control Applications from 15-18 September, 1996. The next IFAC CADCS conference will be held in Belgium in 1997.
More information on activities of the CACSD Technical Committee can be obtained by contacting the Committee Chairman, Assoc. Prof. Grantham Pang, at: Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1; email: pang@excel2.uwaterloo.ca. More information on the IFAC CADCS activities can be obtained from Prof. Dr. Ir. Luc Boullart, Automatic Control Laboratory, Universiteit Gent, Technologiepark, 9, B-9052 Gent-Zwijnaarde, Belgium.
As the above introductory remarks to the special edition indicate, two current international research thrusts are creation of object-oriented engineering environments for implementation of component-based systems and a focus on creation of tools to support design and implementation of hybrid control systems, where hybrid systems are those which exhibit both continuous and discrete states. In addition to the information contained in the papers in this edition, object-oriented approaches are central to the Dymola and Omola modeling languages and is the subject of an Internet discussion group. Also, hybrid systems will be a central theme of the next meeting of the Intelligent Control Technical Committee (August 27-29, 1995 at the Monterey Marriott Hotel in Monterey. CA).
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