Formal Development of Reactive Systems

This chapter presents a case study in the field of control systems. The task consists of developing verified control software for a model representing a production cell installed in a metal-processing plant in Karlsruhe. The paper describes the functionality of the model, explains how the control program relies on the system's sensors, discusses the possibilities for driving the model with the help of various actuators, and finally defines the requirements that are to be fulfilled by the control software. 2.1 Description of the Production Cell The Forschungszentrum Informatik has created a model of a production cell for mounting frames which was built as part of a study in microcomputer technology in 1989. This is not a model only in theory: it represents an actual industrial installation in a metal-processing plant in Karlsruhe. The case study presents a realistic industry-oriented problem, where safety requirements play a significant role and can be met by the application of formal methods. The manageable size of the task allows for experimenting with several approaches. The production cell processes metal blanks which are conveyed to a press by a feed belt. A robot takes each blank from the feed belt and places it into the press. The robot arm withdraws from the press, the press processes the metal blank and