Functional Analysis and System Design Models

Requirements define the system, but they cannot design the system. Systems engineering uses requirements to drive the design in the right direction, but uses a well-structured design process and a series of methods, models, and activities, leading to the final form of the system. System requirements need to be translated into technical specifications. This process of translation requires designers to have the necessary knowledge of the nature of the system and use appropriate models at the right time in the right place. In systems engineering, models are essential for designers to concentrate on the most critical factors of the design, simplifying the situation by ignoring the nonrelevant factors, and thus enabling them to provide a solution for the problem to be addressed. This chapter reviews the most commonly used models for system design; defines the models; describes the functional modeling approach (FFBD); introduces function allocation model; and reviews task analysis, cognitive task analysis, timeline analysis, and link analysis.