Browsing by Author "Reese, Jon"

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    Designing Specification Languages for Process Control Systems: Lessons Learned and Steps to the Future
    (1999) Leveson, Nancy; Heimdahl, Mats; Reese, Jon
    Previously, we defined a blackbox formal system modeling language called RSML (Requirements State Machine Language). The language was developed over several years while specifying the system requirements for a collision avoidance system for commercial passenger aircraft. During the language development, we received continual feedback and evaluation by FAA employees and industry representatives, which helped us to produce a specification language that is easily learned and used by application experts. Since the completion of the RSML project, we have continued our research on specification languages. This research is part of a larger effort to investigate the more general problem of providing tools to assist in developing embedded systems. Our latest experimental toolset is called SpecTRM (Specification Tools and Requirements Methodology), and the formal specification language is SpecTRM-RL (SpecTRM Requirements Language). This paper describes what we have learned from our use of RSML and how those lessons were applied to the design of SpecTRM-RL. We discuss our goals for SpecTRM-RL and the design features that support each of these goals.
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    Experiences From Specifying the TCAS II Requirements Using RSML
    (1998) Heimdahl, Mats; Leveson, Nancy; Reese, Jon
    TCAS II (Traffic alert and Collision Avoidance System II) is an avionics system required on all commercial aircraft with more than 30 passengers. In 1990, FAA deemed the Minimal Operational Performance Standard (MOPS) for TCAS II, expressed in plain English and low-level pseudocode, unacceptable as a basis for government certification. To correct this problem, a high-level software requirements specification (SRS) was developed by reverse engineering the pseudocode and capturing the required behavior using RSML (Requirements State Machine Language), a requirements language based on hierarchical communicating finite state machines [1]. The Irvine Safety Research Group, in cooperation with industrial and government representatives, specified the requirements between 1990 and 1992 [1]. In this paper we provide an overview of this project and the specification technique we used. In the following section we discuss the TCAS II project. Next, we cover some desirable properties of a high-level specification language and provide an overview of RSML. Finally, we share lessons learned and outline current developments.
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    SpecTRM: A CAD SYSTEM FOR DIGITAL AUTOMATION
    (1998) Leveson, Nancy; Reese, Jon; Heimdahl, Mats
    In the system engineering of complex systems that include digital automation, the most vexing and potentially costly problems arise in the early stages of development. Few adequate tools exist to assist in developing system requirements and architectures and translating the system requirements to software requirements. Serious unsolved problems also exist at the other end of the lifecycle in changing or upgrading automated control tasks without introducing errors. In addition, these two system development phases present the most serious and unsolved problems in certification and hazard analysis. SpecTRM-RL (Specification Tools and Requirements Methodology) is a CAD system for digital automation. It is not intended to replace engineers, but instead to use the latest in research ideas to assist engineers in managing the requirements, design, and evolution process.