Chapter 1 Introduction to Systems Engineering

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CHAPTER 1

INTRODUCTION TOSYSTEMS ENGINEERING

MANAGEMENT

1.1 PURPOSE

The overall organization of this text is describedin the Preface. This chapter establishes some ofthe basic premises that are expanded throughoutthe book. Basic terms explained in this chapter arethe foundation for following definitions. Key sys-tems engineering ideas and viewpoints are pre-sented, starting with a definition of a system.

1.2 DEFINITIONS

A System Is …

Simply stated, a system is an integrated compositeof people, products, and processes that provide acapability to satisfy a stated need or objective.

Systems Engineering Is…

Systems engineering consists of two significantdisciplines: the technical knowledge domain inwhich the systems engineer operates, and systemsengineering management. This book focuses onthe process of systems engineering management.

Three commonly used definitions of systemsengineering are provided by the best known tech-nical standards that apply to this subject. They allhave a common theme:

• A logical sequence of activities and decisionsthat transforms an operational need into a de-scription of system performance parameters anda preferred system configuration. (MIL-STD-

499A, Engineering Management, 1 May 1974.Now cancelled.)

• An interdisciplinary approach that encompassesthe entire technical effort, and evolves into andverifies an integrated and life cycle balancedset of system people, products, and process solu-tions that satisfy customer needs. (EIA StandardIS-632, Systems Engineering, December 1994.)

• An interdisciplinary, collaborative approach thatderives, evolves, and verifies a life-cycle bal-anced system solution which satisfies customerexpectations and meets public acceptability.(IEEE P1220, Standard for Application andManagement of the Systems EngineeringProcess, [Final Draft], 26 September 1994.)

In summary, systems engineering is an interdisci-plinary engineering management process thatevolves and verifies an integrated, life-cycle bal-anced set of system solutions that satisfy customerneeds.

Systems Engineering Management Is…

As illustrated by Figure 1-1, systems engineeringmanagement is accomplished by integrating threemajor activities:

• Development phasing that controls the designprocess and provides baselines that coordinatedesign efforts,

• A systems engineering process that providesa structure for solving design problems and

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Figure 1-1. Three Activities of Systems Engineering Management

DevelopmentPhasing

BaselinesLife CyclePlanning

SystemsEngineering

Process

Life CycleIntegration

SystemsEngineeringManagement

IntegratedTeaming

tracking requirements flow through the designeffort, and

• Life cycle integration that involves customersin the design process and ensures that the systemdeveloped is viable throughout its life.

Each one of these activities is necessary to achieveproper management of a development effort. Phas-ing has two major purposes: it controls the designeffort and is the major connection between the tech-nical management effort and the overall acquisi-tion effort. It controls the design effort by devel-oping design baselines that govern each level ofdevelopment. It interfaces with acquisition man-agement by providing key events in the develop-ment process, where design viability can be as-sessed. The viability of the baselines developed isa major input for acquisition management Mile-stone (MS) decisions. As a result, the timing andcoordination between technical developmentphasing and the acquisition schedule is critical tomaintain a healthy acquisition program.

The systems engineering process is the heart ofsystems engineering management. Its purpose isto provide a structured but flexible process thattransforms requirements into specifications, archi-tectures, and configuration baselines. The disci-pline of this process provides the control and trace-ability to develop solutions that meet customerneeds. The systems engineering process may berepeated one or more times during any phase ofthe development process.

Life cycle integration is necessary to ensure thatthe design solution is viable throughout the life ofthe system. It includes the planning associated withproduct and process development, as well as theintegration of multiple functional concerns into thedesign and engineering process. In this manner,product cycle-times can be reduced, and the needfor redesign and rework substantially reduced.

1.3 DEVELOPMENT PHASING

Development usually progresses through distinctlevels or stages:

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Figure 1-2. Development Phasing

Concept Studies

System Definiiton(Functional Baseline)

Preliminary Design(Allocated Baseline)

Detail Design(Product Baseline)

DESIGN DEFINITION

DESIGN DEFINITION

DESIGN DEFINITION

• Concept level, which produces a system conceptdescription (usually described in a conceptstudy);

• System level, which produces a system descrip-tion in performance requirement terms; and

• Subsystem/Component level, which producesfirst a set of subsystem and component productperformance descriptions, then a set ofcorresponding detailed descriptions of theproducts’ characteristics, essential for theirproduction.

The systems engineering process is applied to eachlevel of system development, one level at a time,to produce these descriptions commonly calledconfiguration baselines. This results in a series ofconfiguration baselines, one at each developmentlevel. These baselines become more detailed witheach level.

In the Department of Defense (DoD) the configu-ration baselines are called the functional baselinefor the system-level description, the allocatedbaseline for the subsystem/ component performance

descriptions, and the product baseline for the sub-system/component detail descriptions. Figure 1-2shows the basic relationships between the baselines.The triangles represent baseline control decisionpoints, and are usually referred to as technical re-views or audits.

Levels of Development Considerations

Significant development at any given level in thesystem hierarchy should not occur until the con-figuration baselines at the higher levels are con-sidered complete, stable, and controlled. Reviewsand audits are used to ensure that the baselines areready for the next level of development. As will beshown in the next chapter, this review and auditprocess also provides the necessary assessment ofsystem maturity, which supports the DoDMilestone decision process.

1.4 THE SYSTEMS ENGINEERINGPROCESS

The systems engineering process is a top-downcomprehensive, iterative and recursive problem

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Figure 1-3. The Systems Engineering Process

solving process, applied sequentially through allstages of development, that is used to:

• Transform needs and requirements into a set ofsystem product and process descriptions (add-ing value and more detail with each level ofdevelopment),

• Generate information for decision makers, and

• Provide input for the next level of development.

As illustrated by Figure 1-3, the fundamental sys-tems engineering activities are RequirementsAnalysis, Functional Analysis and Allocation, andDesign Synthesis—all balanced by techniques andtools collectively called System Analysis and Con-trol. Systems engineering controls are used to trackdecisions and requirements, maintain technicalbaselines, manage interfaces, manage risks, trackcost and schedule, track technical performance,verify requirements are met, and review/audit theprogress.

During the systems engineering process architec-tures are generated to better describe and under-stand the system. The word “architecture” is usedin various contexts in the general field of engi-neering. It is used as a general description of howthe subsystems join together to form the system. Itcan also be a detailed description of an aspect of asystem: for example, the Operational, System, andTechnical Architectures used in Command, Con-trol, Communications, Computers, Intelligence,Surveillance, and Reconnaissance (C4ISR), andsoftware intensive developments. However, Sys-tems Engineering Management as developed inDoD recognizes three universally usable architec-tures that describe important aspects of the system:functional, physical, and system architectures. Thisbook will focus on these architectures as neces-sary components of the systems engineeringprocess.

The Functional Architecture identifies and struc-tures the allocated functional and performancerequirements. The Physical Architecture depicts the

PROCESS OUTPUT

PROCESS

INPUT

RequirementsAnalysis

RequirementsLoop

Verification

DesignLoop

Functional Analysisand Allocation

Design Synthesis

System Analysisand Control(Balance)

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system product by showing how it is broken downinto subsystems and components. The SystemArchitecture identifies all the products (includingenabling products) that are necessary to supportthe system and, by implication, the processesnecessary for development, production/construc-tion, deployment, operations, support, disposal,training, and verification.

Life Cycle Integration

Life cycle integration is achieved through inte-grated development—that is, concurrent consid-eration of all life cycle needs during the develop-ment process. DoD policy requires integrateddevelopment, called Integrated Product and Prod-uct Development (IPPD) in DoD, to be practicedat all levels in the acquisition chain of commandas will be explained in the chapter on IPPD. Con-current consideration of all life cycle needs can begreatly enhanced through the use of interdiscipli-nary teams. These teams are often referred to asIntegrated Product Teams (IPTs).

The objective of an Integrated Product Team is to:

• Produce a design solution that satisfies initiallydefined requirements, and

• Communicate that design solution clearly,effectively, and in a timely manner.

Multi-functional, integrated teams:

• Place balanced emphasis on product and processdevelopment, and

• Require early involvement of all disciplinesappropriate to the team task.

Design-level IPT members are chosen to meet theteam objectives and generally have distinctive com-petence in:

• Technical management (systems engineering),

• Life cycle functional areas (eight primaryfunctions),

• Technical specialty areas, such as safety, riskmanagement, quality, etc., or

• When appropriate, business areas such asfinance, cost/budget analysis, and contracting.

Life Cycle Functions

Life cycle functions are the characteristic actionsassociated with the system life cycle. As illustratedby Figure 1-4, they are development, productionand construction, deployment (fielding), opera-tion, support, disposal, training, and verification.These activities cover the “cradle to grave” lifecycle process and are associated with major func-tional groups that provide essential support to thelife cycle process. These key life cycle functionsare commonly referred to as the eight primaryfunctions of systems engineering.

The customers of the systems engineer performthe life-cycle functions. The system user’s needsare emphasized because their needs generate therequirement for the system, but it must be remem-bered that all of the life-cycle functional areasgenerate requirements for the systems engineer-ing process once the user has established the basicneed. Those that perform the primary functionsalso provide life-cycle representation in design-level integrated teams.

Primary Function Definitions

Development includes the activities required toevolve the system from customer needs to productor process solutions.

Manufacturing/Production/Construction in-cludes the fabrication of engineering test modelsand “brass boards,” low rate initial production,full- rate production of systems and end items, orthe construction of large or unique systems or sub-systems.

Deployment (Fielding) includes the activities nec-essary to initially deliver, transport, receive, pro-cess, assemble, install, checkout, train, operate,house, store, or field the system to achieve fulloperational capability.

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Figure 1-4. Primary Life Cycle Functions

VerificationTrainingDisposal

Operation Support

Manufacturing/Production/ConstructionDeployment

Development

8 PrimaryLife CycleFunctions

Operation is the user function and includesactivities necessary to satisfy defined operationalobjectives and tasks in peacetime and wartimeenvironments.

Support includes the activities necessary to pro-vide operations support, maintenance, logistics,and material management.

Disposal includes the activities necessary to ensurethat the disposal of decommissioned, destroyed,or irreparable system components meets allapplicable regulations and directives.

Training includes the activities necessary toachieve and maintain the knowledge and skill levelsnecessary to efficiently and effectively performoperations and support functions.

Verification includes the activities necessary toevaluate progress and effectiveness of evolvingsystem products and processes, and to measurespecification compliance.

Systems Engineering Considerations

Systems engineering is a standardized, disciplinedmanagement process for development of systemsolutions that provides a constant approach tosystem development in an environment of changeand uncertainty. It also provides for simultaneousproduct and process development, as well as acommon basis for communication.

Systems engineering ensures that the correcttechnical tasks get done during developmentthrough planning, tracking, and coordinating.Responsibilities of systems engineers include:

• Development of a total system design solutionthat balances cost, schedule, performance, andrisk,

• Development and tracking of technicalinformation needed for decision making,

• Verification that technical solutions satisfycustomer requirements,

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• Development of a system that can be producedeconomically and supported throughout the lifecycle,

• Development and monitoring of internal andexternal interface compatibility of the sys-tem and subsystems using an open systemsapproach,

• Establishment of baselines and configurationcontrol, and

• Proper focus and structure for system and majorsub-system level design IPTs.

1.5 GUIDANCE

DoD 5000.2-R establishes two fundamentalrequirements for program management:

• It requires that an Integrated Product andProcess approach be taken to design whereverpracticable, and

• It requires that a disciplined systems engineer-ing process be used to translate operationalneeds and/or requirements into a systemsolution.

Tailoring the Process

System engineering is applied during all acquisi-tion and support phases for large- and small-scalesystems, new developments or product improve-ments, and single and multiple procurements. Theprocess must be tailored for different needs and/orrequirements. Tailoring considerations includesystem size and complexity, level of systemdefinition detail, scenarios and missions, con-straints and requirements, technology base, majorrisk factors, and organizational best practices andstrengths.

For example, systems engineering of softwareshould follow the basic systems engineeringapproach as presented in this book. However, itmust be tailored to accommodate the softwaredevelopment environment, and the unique progress

tracking and verification problems software devel-opment entails. In a like manner, all technologydomains are expected to bring their own uniqueneeds to the process.

This book provides a conceptual-level descriptionof systems engineering management. The specifictechniques, nomenclature, and recommendedmethods are not meant to be prescriptive. Techni-cal managers must tailor their systems engineer-ing planning to meet their particular requirementsand constraints, environment, technical domain,and schedule/budget situation.

However, the basic time-proven concepts inherentin the systems engineering approach must be re-tained to provide continuity and control. For com-plex system designs, a full and documented un-derstanding of what the system must do shouldprecede development of component performancedescriptions, which should precede componentdetail descriptions. Though some parts of the sys-tem may be dictated as a constraint or interface, ingeneral, solving the design problem should startwith analyzing the requirements and determiningwhat the system has to do before physical alterna-tives are chosen. Configurations must be controlledand risk must be managed.

Tailoring of this process has to be done carefullyto avoid the introduction of substantial unseen riskand uncertainty. Without the control, coordination,and traceability of systems engineering, an envi-ronment of uncertainty results which will lead tosurprises. Experience has shown that thesesurprises almost invariably lead to significantimpacts to cost and schedule. Tailored processesthat reflect the general conceptual approach of thisbook have been developed and adopted by profes-sional societies, academia, industry associations,government agencies, and major companies.

1.6 SUMMARY POINTS

• Systems engineering management is a multi-functional process that integrates life cyclefunctions, the systems engineering problem-solving process, and progressive baselining.

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• The systems engineering process is a prob-lem-solving process that drives the balanceddevelopment of system products and processes.

• Integrated Product Teams should apply the sys-tems engineering process to develop a life cyclebalanced-design solution.

• The systems engineering process is applied toeach level of development, one level at a time.

• Fundamental systems engineering activities areRequirements Analysis, Functional Analysis/Allocation, and Design Synthesis, all of whichare balanced by System Analysis and Control.

• Baseline phasing provides for an increasinglevel of descriptive detail of the products andprocesses with each application of the systemsengineering process.

• Baselining in a nut shell is a concept descrip-tion that leads to a system definition which, inturn, leads to component definitions, and thento component designs, which finally lead to aproduct.

• The output of each application of the systemsengineering process is a major input to the nextprocess application.