Safety-critical Real-time Applications Research Articles

Design of Flexible and Dependable Real-Time Applications

The design of safety-critical applications must include redundancies aimed at Fault Tolerance purposes. An adaptable use of such redundancies can optimise resource utilisation; in case of faults, it can preserve fundamental services and allow a graceful degradation of the system. A programming notation, named FERT, has been recently introduced for the design of adaptable applications. With this notation, the designer of a safety-critical Real-Time application can specify alternative fault tolerance policies for each component of the application and obtain an adaptable run-time behaviour. This paper is meant as a contribution to this notation and to its possible implementation. Namely, it deals with the specification of a communication semantics (including failure semantics) and with execution support problems such as the definition of value of a computation and adaptive planning at run-time. Some related issues are also addressed as future work.

Architectural principles for safety-critical real-time applications

This paper addresses the general area of computer architectures for safety-critical real time applications. The maximum acceptable probability of failure for these applications ranges from about 10/sup /spl minus/4/ to 10/sup /spl minus/10/ per hour depending on whether it is a military or civil application. Typical examples include commercial and military aircraft fly-by-wire, full authority engine control, satellite and launch vehicle control, ground transport vehicles, etc. Realtime response requirements for these applications are also very demanding, with correct control inputs required every 10 to 100 ms, depending on the application. These dual goals of ultrahigh reliability and real-time response necessitate computer systems that are quite different from other dependable systems in their architecture, design and development methodology, validation and verification, and operational philosophy. This paper highlights these differences by describing each of these aspects of safety-critical systems. Architectural principles and techniques to address these unique requirements are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>