TOP-DOWN VS BOTTOM-UP METHODOLOGIES FOR ADAS SYSTEM DESIGN

Abstract

Selection of the principal design methodology has a significant impact on final product quality, including its evolvability and scalability. The article discusses the features of traditional bottom-up and top-down design methodologies in the context of ADAS (driver assistance and automated driving systems). Necessity of the combined design methodology is shown due to unacceptability of “pure” methodologies for design of this kind of systems. For this purpose, the features and limitations of the top-down approach are considered: commitment to maximum compliance of the developed system with its requirements; methodological rigor of the approach; difficulty of system testing in the process of the development; sensitivity to changes in requirements. The features and limitations of the bottom-up approach are considered: possibility of iterative development with obtaining intermediate results; possibility of using standard components; scalability and flexibility of the developed system; possibility of discrepancy of functions of subsystems to requirements, which may appear only at later stages of development; possible inconsistency in development of separate subsystems and elements. The features and factors of ADAS system development are considered: increased requirements for reliability and safety of the system; heterogeneity of used components. Two stages of ADAS-systems development are distinguished: the stage of intensive development and the stage of extensive evolution. The applicability of one or another methodology to various aspects of ADAS system development and evolution (such as: requirements definition; compositional morphism; scalability and extensibility; stability and sustainability; cost and development time; development capability) is considered. A comparison of themethodologies concludes that there are aspects of technical system design and development in which there is a significant advantage of one or the other of the methodologies. Only the bottomup approach can ensure the proper evolution of the system. However, for complex systems, it is critical to define the initial requirements for the system, which can only be achieved using the topdown methodology.