An Initial Study on Monetary Cost Evaluation for the Design of Automotive Electrical Architectures

One of the many challenges facing electronic ¹ system architects is how to provide a cost estimate related to design decisions over the entire life-cycle and product line of the architecture. Various cost modeling techniques may be used to perform this estimation. However, the estimation is often done in an ad-hoc manner, based on specific design scenarios or business assumptions. This situation may yield an unfair comparison of architectural alternatives due to the limited scope of the evaluation. A preferred estimation method would involve rigorous cost modeling based on architectural design cost drivers similar to those used in the manufacturing (e.g. process-based technical cost modeling) or in the enterprise software domain (e.g. COCOMO).

This paper describes an initial study of a cost model associated with automotive electronic system architecture. The model's intended use is to evaluate system cost drivers in response to various architectural decisions (e.g. choosing a communication bus topology or mapping a function to hardware). The primary cost driver categories explored are design and development, part fabrication, assembly and in-service costs. The preliminary version of this cost model focuses on describing the key influences on cost, but not the entire mathematical model. The paper presents the cost model with the help of influence diagrams and illustrates the use of the cost modeling methodology through an automotive case study - a steer-by-wire system. As future work, we propose to build a cost model and supporting methodology that accounts for architecture evolution to address the issue of evolving architecture requirements as well as when and where to employ new technology in the architecture.