Analysis and Design of Safety-critical, Cyber-Physical Systems

The list of applications classified as safety critical is growing due to emerging contexts such as the Internet of Things that touch the everyday activities of millions of people through smart devices like home automation systems and connected vehicles. These consumer products require high reliability but must be priced competitively. Traditional system development strategies are costly, in part, because traditional verification activities find only a small percentage of defects early in a project and because when discovered late in the development life cycle their repair requires changes to dependent code as well. Our development approach leverages early system architecture knowledge to jump start an architecture-centric development strategy that iteratively establishes traceability among the requirements, architecture, and verification artifacts. A virtual integration strategy makes the current state of the system under development available for analysis early in the product development life cycle. The approach is implemented using the Architecture Analysis and Design Language (AADL) embodied in the Open Source AADL Tool Environment (OSATE). The Architecture-Led Incremental System Assurance (ALISA) toolkit, the latest contribution of our team at the Software Engineering Institute, builds on AADL to provide the constructs and tools for an engineer to specify the integrated system, and to define verification activities that ensure satisfaction of the specification. The results from using the languages and techniques in pilot projects have shown very large cost and time savings, important to holding down costs for consumer-level Internet of Things systems. In this paper we focus on the architecture-led development process and illustrate the support given by ALISA.