Integrated modeling of complex production automation systems to increase dependability

Abstract

In current practice, analysis and development of the same mechatronic component are performed separately for both functional and nonfunctional (for definition see Sect. 3) aspects, often by different engineers and/or engineering teams, and specified in different modeling languages. This gap between the development processes of the different aspects of components leads, on the one hand, to inefficient system development processes and additional iterations between functional and nonfunctional design. On the other hand, it makes for a neglected opportunity to increase system dependability during runtime (Avizienis et al. in IEEE Trans. Dependable Sec. Comput. 1(1):11-33, 2004). By building on basic engineering information, for instance by integrating models containing selected information about a system into its control code, dynamic reconfiguration during runtime helps to increase dependability and reduce risk. Risk in this chapter is defined according to Bertsche as the product of severity of damage and probability of occurrence (Bertsche et al. in Zuverlässigkeit mechatronischer Systeme. Grundlagen und Bewertung in frühen Entwicklungsphasen, Springer, Berlin, 2009, p. 55) and the term dependability is used according to Avizienis et al. (IEEE Trans. Dependable Sec. Comput. 1(1):11-33, 2004): dependability is an integrating concept that encompasses the following attributes: availability (availability in this context is considered as the degree to which a system or component is operational and accessible when required for use, often expressed as a probability (IEEE Std. 610.12-1990, IEEE standard glossary of software engineering terminology, The Institute of Electrical and Electronics Engineers, USA, 1990)): readiness for correct service; reliability: continuity of correct service; safety: absence of catastrophic consequences on the user(s) and the environment; integrity: absence of improper system alterations; maintainability: ability to undergo modifications and repairs (Avizienis et al. in IEEE Trans. Dependable Sec. Comput. 1(1):11-33, 2004, p. 13). Another important term used in this chapter is Quality of Service (QoS). This term has been used recently for different domains. In this chapter QoS is used for the quality that can be assumed when using a substitute strategy to replace another service. This chapter contributes to the design of system availability, reliability, and safety, focusing on complex production automation systems and highlighting the results by introducing application examples from the control of a continuous thermo-hydraulic particle board press.