Cyber-Physical System Requirements - A Model Driven Approach

Abstract

Systems where the physical world interacts extensively with often distributed and networked-software are referred to as Cyber-Physical Systems (CPS). Gathering and analyzing CPS requirements poses unique challenges to the requirements engineering community - a perspective that is sensitive to the scoping and interplay between the cyber, physical and behavioral aspects of the system. The major challenges were identifying and analyzing (1)requirements to address the complexity in the continuous domain, (2)requirements related to the continual behavior of the system, (3)the precise scope of the system, (4)requirements flow down during system decomposition, (5)mode logic and features interactions and, (6)system behavior during mode transitions. Unfortunately there is little guidance in the literature to systematically address these issues. We pursued a model-driven approach to overcome these challenges, which we believe is broadly applicable to CPS requirements elicitation and specification. The variety of modeling techniques we used, served as a crucial aid in the elicitation and discovery of requirements and provided an initial classification of the types of requirements and modeling patterns needed to describe crucial aspects of a CPS. We used a generic patient controlled analgesia (GPCA) infusion pump system as case example to investigate the requirements of a medical CPS and provide an archetype of system development artifacts that could serve as a generic reference standard used by CPS researchers and practitioners.