A Framework for Hazard Analysis of Safety-Critical Computer Controlled Systems

Abstract

Safety-Critical Computer Controlled Systems
(SCCCS) are those systems whose failure could
result in loss of life, significant property
damage, or damage to the environment. There
are many well known examples in application
areas such as medical devices, aircraft flight
control, weapons, and nuclear systems. These
systems consist of a set of functional elements,
controlled by embedded processors that together
achieve a common objective. Most softwarerelated
accidents occurred in SCCCS by
executing flawed programming and instructions.
The research literature currently lacks an
appropriate safety analysis and is fragmented
among activities. The aim of this paper is to
reduce the probability of unsafe system
conditions using a variety of management,
organization and technical measures. The
approach begins with conducting three different
types of hazard analysis techniques to SCCCS
such as Software Failure Mode and Effects
Analysis (SFMEA), Software Fault Tree
Analysis (SFTA) and Systems-Theoretic Process
Analysis (STPA). In this paper, the application
of systems-theoretic approach is implemented on
Ball Position Control System (BPCS) and
performed the comparison between traditional
methods and systemic methods for analysis and
design. The proposed systems-theoretic
approach can be applied to SCCCS in diverse
sectors to identify and control the identified
hazards. There is clear value in developing a
systems-theoretic approach to safety analysis in
SCCCS. Development of a SCCCS based on
our proposed software safety approach
significantly enhanced the safe operation of the
overall system.