Systems Engineering Fundamentals

1.4 The Systems Engineering Process

The systems engineering process is a top-down comprehensive, iterative and recursive problem solving process, applied sequentially through all stages of development, that is used to:
• Transform needs and requirements into a set of system product and process descriptions (adding value and more detail with each level of development),
• Generate information for decision makers, and
• Provide input for the next level of development.

As illustrated by Figure 1-3, the fundamental systems engineering activities are Requirements Analysis, Functional Analysis and Allocation, and Design Synthesis—all balanced by techniques and tools collectively called System Analysis and Control. Systems engineering controls are used to track decisions and requirements, maintain technical baselines, manage interfaces, manage risks, track cost and schedule, track technical performance, verify requirements are met, and review/audit the progress.

During the systems engineering process architectures are generated to better describe and understand the system. The word “architecture” is used in various contexts in the general field of engineering. It is used as a general description of how the subsystems join together to form the system. It can also be a detailed description of an aspect of a system: for example, the Operational, System, and Technical Architectures used in Command, Control, Communications, Computers, Intelligence, Surveillance, and Reconnaissance (C4ISR), and software intensive developments. However, Systems Engineering Management as developed in DoD recognizes three universally usable architectures that describe important aspects of the system: functional, physical, and system architectures. This book will focus on these architectures as necessary components of the systems engineering process.

The Functional Architecture identifies and structures the allocated functional and performance requirements. The Physical Architecture depicts the system product by showing how it is broken down into subsystems and components. The System Architecture identifies all the products (including enabling products) that are necessary to support the system and, by implication, the processes necessary for development, production/construction, deployment, operations, support, disposal, training, and verification.