7. sys-hier-wbs module v1.0

5/25/2018 7. Sys-Hier-WBS Module V1.0

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Space Systems Engineering: System Hierarchy Module

System Hierarchy and

Work B reakdown Structure Module

SpaceSystems Eng ineering , version 1.0


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Space Systems Engineering: System Hierarchy Module 2

Module Purpose: System Hierarchy

To show how one view of the system architecture is captured

by the product breakdown structure (PBS).

To describe the benefits and costs of creating a system

hierarchy.

To show how to capture all of the work necessary for a project

by adding the non-product work to the PBS to create the work

breakdown structure (WBS).


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One View o f the Arch itecture - The

Produc t Breakdown Structu re

The framework and interrelationships of elementsof a system. Typically illustrated by both apictorial and a decomposition diagram depictingthe segments and elements and their interfacesand interrelationships.

Architecture is

described by theSystem Hierarchy orProduct BreakdownStructure (PBS)


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Why B reak a Product Down?

Breaking a large complex problem (project) into smaller pieces makes them

easier to solve since the problems are smaller and specialists can focus

on their functional areas.

But this process of reductionism creates some new problems. Namely,

New interfaces are created between the pieces (subsystems), so they

must be defined and managed.

System resources (e.g., mass or power) must be allocated to thesubsystems and these allocations must be accounted for; and

System performance is also allocated to subsystems, so confidence

must be established that if all of the subsystems perform as desired,

then the system will perform as desired.

The creation of the system architecture, the description and management of

interfaces, the allocation of resources and performances, and

establishing confidence that these allocations are appropriate are all

systems engineering responsibilities.


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More Value to Creating

A System Hierarchy

Organizes the work required

to complete a flight project.

Contains all hardware items,

software items, and

information items (e.g.,

documents, databases).

Provides the basis for

functional analysis.

Characteristics:

Top-down,

Product-based,

Lowest level maps to

cognizant engineer ormanager,

Branch points in hierarchy

show how elements will be

integrated.


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Hierarch ical Level Names and Examples

Hierarchical Level Name Examples

Mission Needs + Object ives + Operation of Everything Necessary to Meet the Objectives

System*Total System = Spacecraft + Launch Vehicle + Ground Support Equipment + CommunicationsSystems (TDRSS, etc .) + NASCOM + POC + Science Data Center + .. .+ Personnel

Segment Flight = Spacecraft Bus + Instruments + Launch Vehicle +...

Element Spacecraf t = Structure + Power + C&DH + Thermal + ...

Subsystem Power = Solar Arrays + Electronics + Battery + Fuses + .. .

Component Solar Arrays = Solar Cells + Interconnects + Cover Glass + ...

Part Solar Cells

*Any given system can be organized into a hierarchy composed of segments and/orelements of succeedingly lower and less complex levels, which may in themselves be

termed systems by their designers. In order to avoid misunderstandings, hierarchical

levels for a given mission must be defined early.


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Sys tem Hierarchy (1/2)

Hierarchy/Hierarchical Levels - The relationship of one item of

hardware/software with respect to items above and below in the

relative order of things.

Mission - An individual system or groups of systems operated to

meet a specific set of objectives.

System - A composite of hardware, software, skills, personnel,and techniques capable of performing and/or supporting an

operational role. A complete system includes related facilities,

equipment, materials, services, software, technical data, and

personnel required for its operation and support to the degree

that it can be considered a self-sufficient unit in its intendedoperational and/or support environment.

The system is what is employed operationally and supported

logistically. (More than one system may be needed to conduct a

mission.)


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Sys tem Hierarchy (2/2)

Segment - A grouping of elements that are closely related and

which often physically interface. It may consist of elements

produced by several organizations and integrated by one.

Element - A complete, integrated set of subsystems capable of

accomplishing an operational role or function.

Subsystem - A functional grouping of components that combine

to perform a major function within an element.

Component - A functional subdivision of a subsystem and

generally a self-contained combination of items performing a

function necessary for subsystem operation. A functional unit

viewed as an entity for purpose of analysis, manufacturing,

testing, or record keeping.

Part - A hardware element that is not normally subject to further

subdivision or disassembly without destruction of designated

use.



System Hierarchy Examp le - Space Shu tt le

System hierarchy is also referred to as the Produ ct B reakdown Structure (PBS).

System

Segment

Element

Subsystem



How complicated it can get

The yel low box es represent the bot tom -level end p roduc ts.



Work Breakdown Structure (WBS)

Definition

A hierarchical breakdownof the work necessary to complete aproject. The WBS should be a product-based, hierarchical

division of deliverable items andassociated services.

The WBS is based on the System Hierarchyor Product

Breakdown Structure(PBS), with the specified prime products

at the top, and the systems, segments, subsystems, etc. atsuccessive lower levels.

At the lowest levelare products, such as hardware and

software for which there is a cognizant engineer or manager.

The WBS is built from the PBS by adding(at each level) thenecessary service elements, such as management, systems

engineering, integration and verification, and logistics support.



Relat ion sh ip Between PBS and WBS

The Product Breakdown

Structure shows thecomponents from whichthe system was formed.

The PBS reflects thework to producethe individualsystem components.

The Work BreakdownStructure shows allwork components necessaryto produce a completesystem.

The WBS reflects thework to integratethe components

into a system.

Subsystem A Subsystem B Subsystem C Management Systems

Engineering

Integration,

Test & Verification

Logistics

Support

System

PBS

WBS



Work Breakdown Structure (WBS)

A Work Breakdown System (WBS) is used for: Task or work package planning and scheduling

Cost estimating or budget formulation

Product development documentation, e.g., documentationtree, systems engineering management plan (SEMP),drawings

Project status reporting and assessment

The WBS should include:

All the work in the project life cycle, in-house and/orcontracted

Hierarchical relationships of all work products

A companion dictionary to describe the content

When should you have a WBS?

Pre-phase A; conceptual design phase; early mission/projectformulation



NASA Standard WBS at Level 2

Flight Development

And Operati ons

Project

Project

Management

01

Systems

Engineering

02

Safety & M ission

Assurance

03

Science /

Technology

04

Payload(s)

05

Aircraft /

Spacecraft

06

Mission

Operations

07

Launch Vehicle /

Services

08

Ground

System(s)

09

Systems Integration

& Testing

10

Education and

Public Outreach

11

Flight Development

And Operati ons

Project

Project

Management

01

Systems

Engineering

02

Safety & M ission

Assurance

03

Science /

Technology

04

Payload(s)

05

Aircraft /

Spacecraft

06

Mission

Operations

07

Launch Vehicle /

Services

08

Ground

System(s)

09

Systems Integration

& Testing

10

Education and

Public Outreach

11

Standard Level 2 WBS Elements for Space Flight Projects

Space Flight

Project

Spacecraft06



Example: NASAs SOFIA Project PBS and WBS

Aircraft Element

Telescope Subsystem Electronics Subsystem

Telescope Element

Airborne Facility Science Instruments

Observatory System

Labs/Offices Facility GSE Mission Planning Simulator

Ground Support System

Sofia Project

Management Systems

Engineering

Project

Integration &

Test

Operations

and Logistics

Planning

Science

Support

Mission

Assurance

Observatory

System

Ground

Support

System

Sofia Project

PBS

WBS


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Pause and Learn Opportun i ty

View the James Webb Space Telescope (JWST) WBS

& Dictionary Baseline document for example

implementation.

(JWST WBS & Dictionary (Baseline).pdf)



Techniques for Developing a WBS

Takes several iterations through the life of the project, since the full

extent of the work is not obvious at the outset.

Develop System Hierarchy / PBS first, from the top down

Develop WBS by adding appropriate services, such as management

and systems engineering to the lower levels

Use a similar structure as a starting point for all product elements ofthe WBS at all levels

Repeat for all levels, starting with project level

Involve people who will be responsible for the lower level WBS

elements.

Document assumptions, e.g., common spacecraft computer and

software; all operations development costs under mission ops;

testbeds and prototype hardware contained within hardware

element etc.



Module Summary: System Hierarchy

A product breakdown structure (PBS) captures the hierarchy ofthe system and is one representation of the system architecture.

Creating a system hierarchy is valuable since it breaks acomplex problem into smaller pieces that will be easier to tackle.

But this reductionism, or decomposition has a price:

New interfaces are created between the pieces (subsystems), sothey must be defined and managed.

System resources (e.g., mass or power) must allocated to thesubsystems and these allocations must be accounted for; and

System performance is also allocated to subsystems, soconfidence must be established that if all of the subsystemsperform as desired that the system will perform as desired.

The work breakdown structure (WBS) extends the PBS in that itcaptures allof the work necessary for a project by adding thenon-product work necessary for a successful project (e.g.,integration, test, logistics support, systems engineering andmanagement).


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Backup Sl ides

for System Hierarchy Module

Note slides 26-28 demonstrate some common errors in

PBS and WBS structure. The pilot students found

these useful, so they could be included in the body of

the lecture.

NASA Space Flight Project



NASA Space Flight ProjectStandard WBS Dictionary (1/4)

Element 1 Project Management: The business and administrative planning, organizing,directing, coordinating, analyzing, controlling, and approval processes used to accomplishoverall project objectives, which are not associated with specific hardware or software

elements. This element includes project reviews and documentation, non-project ownedfacilities, and project reserves. It excludes costs associated with technical planning andmanagement and costs associated with delivering specific engineering, hardware andsoftware products.

Element 2 Systems Engineering: The technical and management efforts of directing andcontrolling an integrated engineering effort for the project. This element includes theefforts to define the project space flight vehicle(s) and ground system, conducting tradestudies, the integrated planning and control of the technical program efforts of design

engineering, software engineering, specialty engineering, system architecture developmentand integrated test planning, system requirements writing, configuration control, technicaloversight, control and monitoring of the technical program, and risk management activities.Documentation products include requirements documents, interface control documents(ICDs), Risk Management Plan, and master verification and validation (V&V) plan.Excludes any design engineering costs.

Element 3 Safety and Mission Assurance: The technical and management efforts of

directing and controlling the safety and mission assurance elements of the project. Thiselement includes design, development, review, and verification of practices and proceduresand mission success criteria intended to assure that the delivered spacecraft, groundsystems, mission operations, and payload(s) meet performance requirements and functionfor their intended lifetimes. This element excludes mission and product assurance effortsdirected at partners and subcontractors other than a review/oversight function, and the

direct costs of environmental testing.





Element 4 Science / Technology: This element includesthe managing, directing, andcontrolling of the science investigation aspects, as well as leading, managing, andperforming the technology demonstration elements of the Project. The costs incurred to

cover the Principal Investigator, Project Scientist, science team members, and equivalentpersonnel for technology demonstrations are included. Specific responsibilities includedefining the science or demonstration requirements; ensuring the integration of theserequirements with the payloads, spacecraft, ground systems, and mission operations;providing the algorithms for data processing and analyses; and performing data analysisand archiving. This element excludes hardware and software for onboard scienceinvestigative instruments/payloads.

Element 5 Payload: This element includes the equipment provided for special purposes

in addition to the normal equipment (i.e., GSE) integral to the spacecraft. This includesleading, managing, and implementing the hardware and software payloads that performthe scientific experimental and data gathering functions placed on board the spacecraft, aswell as the technology demonstration for the mission.

Element 6 Spacecraft(s):The spacecraft that serves as the platform for carryingpayload(s), instrument(s), humans, and other mission-oriented equipment in space to themission destination(s) to achieve the mission objectives. The spacecraft may be a single

spacecraft or multiple spacecraft/modules (i.e., cruise stage, orbiter, lander, or rovermodules). Each spacecraft/module of the system includes the following subsystems, asappropriate: Crew, Power, Command & Data Handling, Telecommunications, Mechanical,Thermal, Propulsion, Guidance Navigation and Control, Wiring Harness, and FlightSoftware. This element also includes all design, development, production, assembly, testefforts, and associated GSE to deliver the completed system for integration with the launchvehicle and payload. This element does not include integration and test with payloads andother project systems.





Element 7 - Mission Operations System: The management of the developmentand implementation of personnel, procedures, documentation, and trainingrequired to conduct mission operations. This element includes tracking,commanding, receiving/processing telemetry, analyses of system status,trajectory analysis, orbit determination, maneuver analysis, target bodyorbit/ephemeris updates, and disposal of remaining end-of-mission resources.The same WBS structure is used for Phase E Mission Operation Systems butwith inactive elements defined as not applicable. However, different accountsmust be used for Phase E due to NASA cost reporting requirements. This

element does not include integration and test with the other project systems.

Element 8 Launch Vehicle / Services: The management and implementationof activities required to place the spacecraft directly into its operationalenvironment, or on a trajectory towards its intended target. This elementincludes launch vehicle, launch vehicle integration, launch operations, any otherassociated launch services (frequently includes an upper-stage propulsion

system), and associated ground support equipment. This element does notinclude the integration and test with the other project systems.





Element 9 Ground System(s): The complex of equipment, hardware, software,networks, and mission-unique facilities required to conduct mission operationsof the spacecraft systems and payloads. This complex includes the computers,

communications, operating systems, and networking equipment needed tointerconnect and host the Mission Operations software. This element includesthe design, development, implementation, integration, test, and the associatedsupport equipment of the ground system, including the hardware and softwareneeded for processing, archiving, and distributing telemetry and radiometricdata and for commanding the spacecraft. Also includes the use andmaintenance of the project testbeds and project-owned facilities. This element

does not include integration and test with the other project systems andconducting mission operations.

Element 10 Systems Integration and Testing: This element includes thehardware, software, procedures, and project-owned facilities required toperform the integration and testing of the projects systems, payloads,spacecraft, launch vehicle/services, and mission operations.

Element 11

Education and Public Outreach: Provide for the education andpublic outreach (EPO) responsibilities of NASAs missions, projects, andprograms in alignment with the Strategic Plan for Education. Includesmanagement and coordinated activities, formal education, informal education,public outreach, media support, and website development.


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Rules for the NASA Standard WBS

1. The Project Name will be WBS Level 1.

2. The title of each WBS Level 2 element can be modified to facilitate project-unique

titles, but the content of each must remain the same. If the linkage of the project-unique title to the standard title is not intuitive, the project-unique title is cross-referenced to the standard.

3. If the set of standard WBS Level 2 elements does not comprise an exhaustive set ofWBS elements, additional WBS elements may be added horizontally (i.e., at Level 2)as long as their content does not fit into the content of any existing standard WBS

elements.4. For each standard WBS Level 2 element, the subordinate (children) WBS elements

at Level 3 and lower will be determined by the project.

5. The Level 3 and lower elements can differ from project to project but will includeonly work that rolls up to the standard WBS Dictionary definition of the Level 2element. (See back-up for definitions.)

6. If there is no work to fit into a standard WBS element, then an inactive placeholderelement (and an inactive placeholder financial code) will be established.

7. A single WBS will be used for both technical/business management and reporting.

8. The management assigned to each WBS element may differ from project to project.


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Common WBS Error s (1/3)

Management Engineering Fabrication Verification

Project

Error 1: Functions without products.

The WBS describes functions not products.

This makes the project manager the only one formally

responsible for products.


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Software Hardware

Distributed

Information

System

Error 2: Inappropriate branches

The WBS has branch points that are not consistent with how

the WBS elements will be integrated.

Inappropriate to separate hardware and software as if they are

separate systems to be integrated at the system level.

This makes it difficult to assign accountability for integrationand to identify the costs of integrating and testing components

of a system.


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TelescopeAssembly

Optics/Mirror

Subsystem

Error 3: Inconsistency with PBS

The WBS is inconsistent with the PBS.

This makes it possible that the PBS will not be fully

implemented, and complicates the management process.

XXX YYY

ZZZ Optics/Mirror

TelescopeAssembly

Subsystem

The Work Breakdown System The Product Breakdown System


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Space Systems Engineering: System Hierarchy Module

Add i t ional in format ion for WBS module

related to o rganizat ional stru ctu re


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Relat ionship Between WBS and Organizat ion

Organizational structure for a program and/or project

usually aligns with the WBS. Although the staffing ofthe functions can be addressed in a variety of ways

based on the culture and size of the organization.

Good reference on engineering organizational

structures: Systems Engineering Management byBenjamin Blanchard (chapter 7)

Matrix organization structure (section 7.3.3)

Producer organization (combined project-functional structure)

(section 7.3.4)

Examples:

Exploration Systems (see next chart)


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Organizat ional Struc ture for Exp lorat ion

Suppliers

National

Subcontractor

National

Prime Contractor

Lockheed-Martin

National

Service Module

GRCOhio

Launch Escape

SystemLaRC

Virginia

Non-Prime

(in-house) work

CEV/Orion Project Office

JSCHouston, TX

Ares 1 Launch Vehicle Project Office

MSFCHuntsville, AL

Launch Systems Project Office

KSCFlorida

Constellation Program Office

Johnson Space Center (JSC)

Houston, TX

NASA Headquarters

Exploration Systems Mission Directorate

Washington, DCLevel 1

Level 2

Level 3

Level 4

Example for NASA human spaceflight effort.

Reflects derivation of authority from HQ to

Program to Projects.

Requirements flow in same top-down direction.


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Organizat ional Structu re of Level 2 Box

Constellation Program


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SE&I DirectorChris Hardcastle

Deputies

Charlie Lundquist-Transition & IntegrationDavid Petri Planning & Performance

CoS Organization Jason Weeks (A)Secretary-Tina Cobb (C)

Secretary-LaNell Cobarruvias (C)

Constellation ProgramSystems Engineering & Integration (SE&I)

SE&I Offices, CxP Offices& Center SE&I Focals

Technical StaffCoST/CxAT Focal - John Baker (M)

Chief Architect: Bret Drake**Verification: John Kennedy

SIP/Time Phased Capability: Keith WilliamsAvionics & SW: Jeff Stephenson

Horizontal IntegrationTBD/Tracy Hom

Vertical IntegrationBurt Laws/

Steve Meacham (M)/Renee Cox (M)

Supportability/Operability/AffordabilityKevin Watson/TBD

Level I& Level 3 Projects

SW & AvionicsIntegration OfficeChief: Monte GoforthDeputy: Don Monell

CSCP/M&SWG

DSILWG

Analysis, Trades &Architecture

Chief: Neil LemmonsChief: Dave Forrest (A)Deputy: Deb Ludban (A)

AWG

Process, Requirements& Interface Mgt Office

Chief: Michele DiGiuseppeDeputy: Debbie Korth

RICWG

PSEOffice

CxAT

Jerry Hill (M) - Ares 1-X SE&I Interface & SERP Rep

* = Technical Mgr for all MSFC Level II Program SEI activities in support of SE Office Chiefs.** = Post LAT 2 Team AssignmentM = Matrixed

A = ActingC = Contractor

Steve Meacham (M) -Technical Mgr Integ. MSFC*

Program TechnicalIntegration

Chief: Margarita SampsonDeputy: Nancy Srb

Deputy: Kerri Knotts **

PTI Forum

ZF211

ZF111

ZF311 ZF411 ZF511

In these Numbers:Partial funding provided by NASA HQ &some Procurement S (converted to Eps here)

ALL to be scrubbed as apart of Pending PPBE/ITA revision

SECB

7. sys-hier-wbs module v1.0

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