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Learning objectives • Be able able to defin define e a system. system. • Describe Describe how systems systems engineering engineering adds value to the development of large projects.
Systems Engineering – Introduction and Lifecycle
• Describe Describe the common common project lifecycle lifecycle phases, their purpose, activities, products and the review gates that separate them. • Define what a system baseline is. • Link project project life cycle cycle phases to to the “V” systems systems engineering process model. 2
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Armour
References • “NASA systems engineering engineering handbook”, handbook”, NASA SP2007-6105 Rev.1, NASA HQ, Washington DC, December 2007. • “Systems Engineering Engineering Handbook”, Handbook”, International International Council Council of Systems Engineering (INCOSE), Version 3.1 (or v2a) • ISO/IEC 15288 (IEEE (IEEE STD STD 15288-2008), 15288-2008), Systems Systems and software engineering. • “National Airspace Airspace System System Engineering Engineering Manual”, Federal Aviation Administration ATO-Planning, Version 3.1, 2006
What do these have in common?
Hand tools
House Bicycle
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Dugout Canoe
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Why Systems Engineering?
The problem
New aerospace systems are more likely to have: Vasa, Sweden, 1628
♦
Technology development
♦
A variety of subsystem technical maturities
♦
Consider and reuse existing designs
• Systems built by different different subsystem groups do not perform system functions and fail at the interfaces
♦
COTS subsystems and/or mandated subsystem suppliers
♦
Greater dependence dependence on system models for design decisions
• Managers Managers and and chief enginee engineers rs pay attention attention to to their skill skill areas • Developed Developed systems systems not usable usable
♦
More stakeholders, institutional partners, constraints and ambiguity
• A study of 40 recent recent NASA NASA missi missions ons showed showed avg. avg. cost cost growth of 27% and avg. schedule growth of 22%. 5
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More customer oversight and critical r eview
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‘System-of-systems’ r equirements equirements
♦
More people people - project sizes are growing growing
♦
Geographically Geographically distributed design teams
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Definitions
Definitions cont… What is Systems Engineering?
“A System is a set of interrelated components which interact with one another in an organized fashion toward a common purpose”
“Systems Engineering is an interdisciplinary approach and means to enable the realization of successful systems. It focuses on defining customer needs and required functionality early in the development cycle, documenting requirements, and then proceed ing with design synthesis and system validation while considering the complete problem. Systems Engineering considers both the business and the technical needs of all customers with the goal of providing a quality product that meets the user needs.”
NASA Systems Engineering Handbook SP6105 ‘International Council on Systems Engineering’ (INCOSE) Handbook
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Complex
Which of these is a system? ♦
Decompose complex problem into smaller, easier to solve problems
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Systems engineering divides complex development projects by product and phase.
♦
Decomposing a product creates a hierarchy of progressively smaller pieces, e.g:
1. A tree 2. A h ou se 3. A town 4. An HR department
simple
♦
♦
System, Segment, Assembly, Subassembly, Subsystem, Element, Component, Part
Decomposing the development life of a new project creates a sequence of defined activities, e.g: ♦
Requirements, Design, Integrate, Verify, Operate, Dispose
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Decomposing by product System
Decomposing by phase
Spacecraft
♦
Lifecycle phases are used to help plan and manage all major aerospace system developments.
♦
Everything that should be done to accomplish a project is divided into distinct phases , separated by control gates .
Payload
Subsystem Components
Power
Structure
Propellant tanks
Propulsion
Piping and valves
Attitude and Orbit Control
Thrusters
Telecoms etc.
Pressurant tanks etc.
•
Parts
Tubing
Brackets
♦ NR valves
For space projects, the phases are lettered: PrePhase A, Phase A, Phase B, Phase C, Phase D, Phase E, Phase F
Phase boundaries are defined at natural points for project progress assessment and go/no go decisions.
On/off valves
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Life cycle example: Space
Generic life cycle Phase Definition of needs
Problems
Concept & Technology Development
Prelim. Design
CONOPS
Concepts Expectations
Preliminary Design & Tech Completion
System Reqmts. Validation Plan
Subsystem Reqmts. Verificat’n Plan
Engineering design and build
Design-to Specs Build-to Specs Verificat’n Procedures
Assembly and test
As-built
As-verified
Phase Title
Asoperated
End of Phase Review
Produce a broad spectrum of ideas and concepts, establish mission objectives
Mission Concept Review (MCR)
Concept Studies
Phase A
Concept and Technology From multiple approaches develop a single system System Definition Review Development concept for the mission, with system requirements and (SDR) architecture. Perform trade studies and identify needed technologies.
Phase B
Preliminary Design and Establish a preliminary design, with subsystem Technology Completion requirements, interfaces, and with technology issues resolved.
Phase C
Final Design and Fabrication
Complete the design and drawings, purchase or manufacture parts and components, code software.
Phase D
System Assembly, Integration, Test and Launch
Assemble subsystems, integrate subsystems to create Readiness Review (RR) systems, test to verify and validate performance, deploy the system.
Phase E/F
Operation and Sustainment/Closeout
Operate System, decommissioning, disposal
Operations
Asdeployed
Purpose
Pre-Phase A
Anomalies
Preliminary Design Review (PDR)
Critical Design Review (CDR)
Decommissioning Review
Image credit: http://education.ksc.nasa.gov
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Baseline
Control gates for reviews
• Each milestone review creates a new ‘baseline’
• Read: http://www.fhwa.dot.gov/cadiv/segb/views/document/sect ions/Section3/3_9_10.htm • And section 6.7.2.1 of NASA Systems Engineering Handbook (on blackboard) • Answer the questions:
• A ‘baseline’ is both a noun and a verb. – Noun: an agreed set of req uirements or designs – Verb: process of establishing an a ba seline. • The baseline will have changes controlled through a formal approval monitoring, or configuration management process.
1. Define and explain MCR, SRR, PDR, CDR, SIR, TRR, FAR? 2. How do they fit in to the ‘V’ product lifecycle?
• Baselines are powerful tools in ensuring the entire team is working with the same requirements, designs, constraints, assumptions, interfaces, resource allocations and team responsibilities. 16
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Alternatives
‘V’ diagram
Alternatives exist to the lifecycle model described: • Rapid prototyping - produces partially operational mock-ups early in the design. Iterative development. • Spiral development - often used in the software industry, iterative but allows incremental releases/refinement each time around the spiral. • Skunkworks (Lockheed) - fasttracking “A skunkworks is a small team that assumes or is given responsibility for developing something in a short time with minimal management constraints. A skunkworks is sometimes used to spearhead a product design that thereafter will be developed according to the usual process.” From: http://searchcio.techtarget.com/definition/skunkworks
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Spiral development model
Exercise
Read the article at: http://www.globalsecurity.org/intell/systems/predator.htm 1. What are the 3 segments of Predator? 2. What are the subsystems of the UAV? 3. List the different causes of Predator losses mentioned in the article. Which segment do they relate to?
Boehm, 1988
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Summary
Next: Requirements capture Requirements are statements about what the system must do and how it must do it. This is equivalent to defining the system boundary and system interfaces.
♦
A system is…
♦
A project is divided into distinct life cycle phases.
♦
These phases are separated by control gates typically associated with a major project review, such as preliminary design review (PDR).
♦
Each project phase has a distinct purpose and set of products.
♦
At the end of each phase a new system baseline — or an agreed-to set of requirements, designs, or documents — is established.
System Boundary System Interface
System Interface
Interface
Element
Element Interface
Element
Interface
.
Element
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