TRIO: A logic language for executable specifications of real-time systems

The TTM/RTTL (timed transition model with real-time temporal logic) framework is presented for modeling, specifying, and analyzing real-time discrete-event systems. TTMs are used to represent the process of the plant and its controller. RTTL is the assertion language for specifying plant behavior and verifying that a controller satisfies the specification. The framework adapts features from the program verification literature which are useful for posing problems of interest to the control engineer, such as modular synthesis and design. Examples are used to illustrate the ideas presented. The authors' published analytical results are summarized and referenced. >

A framework for real-time discrete event control

This paper describes a timed, multithreaded object modeling notation for specifying real-time, concurrent, and reactive systems. The notation Timed Communicating Object Z (TCOZ) builds on Object Z's strengths in modeling complex data and algorithms, and on Timed CSP's strengths in modeling process control and real-time interactions. TCOZ Is novel in that it includes timing primitives, properly separates process control and data/algorithm issues and supports the modeling of true multithreaded concurrency. TCOZ is particularly well-suited for specifying complex systems whose components have their own thread of control. The expressiveness of the notation is demonstrated by a case study in specifying a multilift system that operates in real-time.

/pdf/timed-communicating-object-z-4b62jo4fk2.pdf

Timed Communicating Object Z

Addresses the problem of formally analyzing the properties of real-time systems. We propose a method based on modeling the system as a timed Petri net and on specifying its properties in TRIO, an extension of temporal logic suitable for dealing explicitly with time and for measuring it. Timed Petri nets are axiomatized in terms of TRIO, so that their properties can be derived as theorems in the same spirit as the classical Hoare method allows one to prove properties of programs coded in a Pascal-like language. The method is also illustrated through an example. >

Proving properties of real-time systems through logical specifications and Petri net models

Specification of software for safety critical, embedded computer systems has been widely addressed in literature. To achieve the high level of confidence in a specification's correctness necessary in many applications, manual inspections, formal verification, and simulation must be used in concert. Researchers have successfully addressed issues in inspection and verification; however, results in the areas of execution and simulation of specifications have not made as large an impact as desired.In this paper we present an approach to specification-based prototyping which addresses this issue. It combines the advantages of rigorous formal specifications and rapid systems prototyping. The approach lets us refine a formal executable model of the system requirements to a detailed model of the software requirements. Throughout this refinement process, the specification is used as a prototype of the proposed software. Thus, we guarantee that the formal specification of the system is always consistent with the observed behavior of the prototype. The approach is supported with the NIMBUS environment, a framework that allows the formal specification to execute while interacting with software models of its embedding environment or even the physical environment itself (hardware-in-the-loop simulation).

/pdf/specification-based-prototyping-for-embedded-systems-12zg2h7kdg.pdf

Specification-based prototyping for embedded systems

RT-ASLAN, a formal language for specifying real-time systems, is an extension of the ASLAN specification language for sequential systems. Some of the features of the ASLAN language, such as constructs for writing procedural semantics in a nonprocedural logical language, are highlighted. The RT-ASLAN language supports specification of parallel real-time processes through arbitrary levels of abstraction; processes do not have to be specified to the same level of detail. Communicating processes use an interface process as an abstract data type representing shared information. From RT-ASLAN specifications, performance correctness conjectures are generated. These conjectures are logic statements whose proof guarantees that the specification meets critical time bounds. A detailed example as well as a discussion of the advantages and disadvantages of formal specification and verification are included.

Richard Allen Kemmerer

Papers

RT-ASLAN: A specification language for real-time systems

RT-ASLAN: A specification language for real-time systems