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3. Design 1
Agenda for Design Activity
1. Objective 2. Design concepts 3. A design process 4. Optimizing design 5. Example 6. Other design processes 7. Homework
3. Design 2
1. Objective
Design activity Product-based activities Products used to manage Completion criteria
1. Objective
3. Design 3
Design Activity
The design activity produces a plan defining how the product is to be built and specifying the lower products from which the product is to be constructed.
1. Objective
3. Design 4
Design Tasks
Preliminarydesignreview
Criticaldesignreview
Develop product concept
Develop product design
concept design
spec &
I/Fs
lower specs & I/FsDevelop
lower specs & interfaces
approval approval
1. Objective
3. Design 5
Completion Criteria
Design documented to the point that someone else can acquire lower parts, build, test, and sell off the product
1. Objective
3. Design 6
Pseudo Completion Criteria
Critical design review is complete
1. Objective
3. Design 7
2. Design Concepts
Source of requirements Goal of design
2. Design concepts
3. Design 8
Source of Requirements
Design context Design Vs requirements Pseudo customers guiding design Example pseudo customers
2. Design concepts
3. Design 9
Design Context
Level N Spec
Level N+1 Spec 1
Level N+1 Spec 2
Level N+1 Spec M
Level NDesign
Level N+2 Spec 1
Level N+2 Spec 2
Level N+2 Spec P
Level N+1Design 2
Level N+1Design 1
Level N+1Design M
Design occurs at each level and produces lower specs2. Design concepts
3. Design 10
Design Vs Requirements
Level N Spec
Level N+1 Spec 1
Level N+1 Spec 2
Level N+1 Spec M
Level NDesign
Design at level N becomes requirements at level N+1
Requirements as seen by level N+1
Design as seen by level N
2. Design concepts
3. Design 11
Pseudo Customers Guiding Design
Level N Spec
Level N+1 Spec 1
Level N+1 Spec 2
Level N+1 Spec M
Level NDesign
Pseudo customers guide design in addition to higher-level requirements.
Pseudo Customers
2. Design concepts
3. Design 12
Pseudo Customers
Enterprise Other customers Development process Other stakeholders
2. Design concepts
3. Design 13
Goal of Design
Meeting all customer requirements Meeting all pseudo customer requirements Making the product work
2. Design concepts
3. Design 14
Meeting All Customer Requirements
Customer requirements documented in the spec & interfaces from the higher product
Work is guided by the SOW from the higher product
2. Design concepts
3. Design 15
Meeting All Pseudo-Customer Requirements
Documented as part of design Imposed on the product as a black box
2. Design concepts
3. Design 16
Making the Product Work
Making the product work includes adding all those features necessary to make the system work including such things as
Form and fit Turning the product on Loading the product Testing the product Providing build and test features Interacting with operators
2. Design concepts
3. Design 17
3. A Design Process
Conceptualization Characterization Preliminary Design Review (PDR) Critical Design Review (CDR) Documenting the design
3. A design process
3. Design 18
Conceptualization
CDRPDR
Design Tasks
Preliminarydesignreview
Criticaldesignreview
Develop product concept
Develop product design
concept design
spec &
I/Fs
lower specs & I/FsDevelop
lower specs & interfaces
approval approval
Characterization
3. Design 19
Conceptualization
The act of conceiving a notion of what the product is and how it will be built.
Output is the concept, which gives a high-level description of the product sufficient for planning and guiding the design.
3. A design process
3. Design 20
Variety of Design
Design is difficult to describe as a process because details depend upon many factors such as experience and nature of product
House
Telephone
Radio
Car
Airplane
3. A design process
3. Design 21
Characterization
Converting the concept into the design. Output is the documented design, which
specifies lower products and guides building the product.
Goal to ensure requirements are met & product works
3. A design process
3. Design 22
Parallel Characterization Tasks
Partitioning Making the product work Allocating design requirements
Partitioning
Making the product work
Allocating design requirements
customer & pseudo
customer black-box
requirements
characterization
3. A design process
3. Design 23
Partitioning
Dividing the product into lower products Many reasons for dividing the product may exist
3. A design process
3. Design 24
Partitioning Requirements
Need to build Feasibility Contractual arrangements
3. A design process
3. Design 25
Partitioning Criteria
Similarity to something done before Cost Schedule Performance Reusability and COTS Functional cohesion and uncoupling
3. A design process
3. Design 26
Partitioning Completion Criteria
Partitioning criteria satisfied Team consensus Preliminary design review (pseudo criteria)
3. A design process
3. Design 27
Making Product Work
Other techniques
Life cycle use
Theory of operation
Requirements
Physical diagram
Functional diagram
Data diagram
Performance
Control
Making product
work
Making the product work is the result of applying several techniques in parallel.
Concept
3. Design 28
Requirements
PerformancePhysical
constraints
Reliability
Maintainability
Deployability
Availability
Environmental conditions
Transportability
Materials, processes,
parts
Electromagnetic radiation
Workmanship
Interchangeability
Safety
Human factors
System security
Computer resources
Logistics
Personnel & training
Producibility
Requirements
3. Design 29
Physical Diagram
Sensor
Navigation
GPS
ProcessorWarheadMotor
Airframe
Fin
Fin
3. A design process
3. Design 30
Functional Diagram
Collect imagery
Extracttarget from
image
Predict target
location
Steer missile
Determine missile position
Determine attitude
attitude
position
imagerytarget locationprediction
3. A design process
3. Design 31
Functional Flow Block Diagrams
Start motor
2.0
Initialize
1.0
Guide during initial phase
3.0
Guide during midcourse
4.0
Guide during terminal
5.0
Impact
6.0
Functional flow block diagrams (FFBDs)provide time sequences. FFBDs can be hierarchical and many FFBDs are needed to define
a product3. A design process
3. Design 32
Data Diagram
Collect imagery
Extracttarget from
image
Predict target
location
Steer missile
Determine missile position
Determine attitude attitude
position
imagerytarget
locationprediction
3. A design process
3. Design 33
Performance
Launch
Initial
MidcourseTerminal
Impact
Range
Accuracy
Range
Accuracy
Weight & cost
Performance parameters may influence design
3. A design process
3. Design 34
Logical Control
Selects from among a finite set of discrete options
Power control Initialization Loading control Configuration control Test Vs operation selection Control of operation
3. A design process
3. Design 35
State Variable Control
Continuous within the bounds of measurement resolution
Flight control Process control
3. A design process
3. Design 36
State and Status
State -- a condition the system is in Status -- another word for “state”, often used to
indicate health If the words “state” and “status” are both used in
a design, a clear definition of when each word applies reduces confusion
Using the words “state” or “status” with an adjective also reduces confusion; e.g., power state, failure status
3. A design process
3. Design 37
Modes
Mode -- a manner of acting; often used interchangeably with the word “state”
If the words “state” and “mode” are both used in a design, a clear definition of when each word applies reduces confusion
Using the words “state” or “mode” with an adjective also reduces confusion; e.g., power state, transmit mode
3. A design process
3. Design 38
Reconfiguration
Choosing from redundant elements; e.g.., transmit channels, power supplies, engines
Increases the operation time between repairs
3. A design process
3. Design 39
Reconfiguration Justification
Need reason for expensive in design and test Customer requirements such as preference or
mean time between critical failure We can, it’s more elegant, or we can’t say no
to ourselves
3. A design process
3. Design 40
Other Techniques
Theory of Operation -- A tutorial description of the way the product operates. This tutorial should describe operation during the complete life cycle
Life Cycle Use -- A timeline showing the most common use of the product in each phase of its life.
3. A design process
3. Design 41
Allocating Design Requirements
Flowdown Flowdown and design studies
3. A design process
3. Design 42
Flowdown
Level N Spec
Level N+1 Spec 1
Level N+1 Spec 2
Level N+1 Spec M
Level NDesign
Pseudo Customers
Level N+1 Interfaces
Level N+1 Test Equip
SOWS
Flow down from requirements to design to lower specs, interfaces, and SOWs
Flowdown
3. A design process
3. Design 43
Flowdown and Design Studies
Design
spec
lower spec 1
lower spec 2
design study
Verification by analysis
Verification
FCA
Design studies used to expand requirements or to handle requirements verified by analysis need to be captured for use in
verification by analysis, verification, and PCA
capture
configuration management
3. A design process
3. Design 44
PDR
Performed when approach is established Objective -- design headed in right direction Determines
Approach will work Designers understand customer & requirements Top-level diagrams available Theory of operation understood Design covers all program phases Risk
3. A design process
3. Design 45
CDR
Performed when product is ready for build Objective -- design complete Determines
Design covers all program phases Risk Design can be tested Lower products & I/Fs specified and compatible
3. A design process
3. Design 46
Design Documentation
Paper
Files within a
file manager
Data base
Files within an intranet
Understandable 10 9 7 8Electronic no yes yes yesEasy to enter data 7 10 7 10Easy to view data 10 9 3 10Easy to keep current 3 10 7 9Easy to correct 3 10 7 10Easy to navigate 6 8 3 10Easy to capture design 5 10 3 10Acceptability 10 9 5 8
Design needs to be documented to the point the product can be built and tested. Several method exist. Intranet is becoming popular
Method
3. Design 47
4. Optimizing Design
Waterfall process Modified waterfall process Providing information when needed
4. Optimizing design
3. Design 48
Waterfall Process
System design
Box design
Software design
Softwarei&t
Boxi&t
Systemi&t
Waterfall process has classic V pattern. Steps are serial with each step finishing before the next starts
4. Optimizing design
3. Design 49
Modified Waterfall Process
System design
Box design
Software design Software
i&t
Boxi&t
Systemi&t
Modified waterfall process has shorter cycle time because it starts tasks earlier and allows tasks to develop in parallel through
techniques such as multiple builds.
Tasks start earlier
Software and box developed in multiple builds
4. Optimizing design
3. Design 50
Providing Information when NeededPercent of requirements
complete
0
100
Concept Functions I/Fs Mechanical Test
Percent of tasks to be developed0 100
Development can start before requirements are complete
4. Optimizing design
3. Design 51
5. Example
Understand customer process Customer requirements Design process Concept Spec tree Development of requirements Requirements
5. Example
3. Design 52
Understand Customer Process
Productrequirements
review
Assist customer in developing
product requirements and
interfaces
initial SOW, spec, & I/Fs
final SOW, spec, & I/Fs
approval
5. Example
3. Design 53
Customer Wants
W1: Live in a quiet place W2: Have low maintenance costs W3: Raise a garden W4: Have room for family to visit W5: Have adequate electricity W6: Have a garage W7: Cool in the evenings W8: Pay $100,000 W9: Obtain 6/1/99
5. Example
3. Design 54
Converting Wants to Spec and SOW
W1: quiet
W2: low costs
S01: <3yrsS04: no floodS05: low maintS12: equip works
S02: miles
W3:garden
S03: 1/2 acreS11: water
W4: family
W5: electric
W6: garage
W7: cool
W8: $100K
W9: close
S06: 1800S07: 3 bdr
S10: 100 amps
S09: garage
S08:east
C2:$100K
C3:close
Wants
Spec SOW
Wants flow to spec and SOW either directly or through studies. It is desirable to document these studies.
S S S S S S
C1: house & lot
3. Design 55
Product SOW
C1: Provide house and lot that meet spec (ANA) C2: Pay $100,000 (INS) C3: Close on sale by 6/1/99 (INS)
5. Example
3. Design 56
Product Spec
S01: <3 years old (ANA) S02 <10 & > 3 miles from town of 5000 people (INS) S03 > 1/2 acre lot (INS) S04 Does not flood (ANA) S05 Low maintenance construction (INS) S06: >1800 feet in air conditioning (INS) S07: At least 3 bedrooms (INS) S08: Master bedroom on east side (INS) S09: Attached two-car garage (INS) S10: >100 amperes electrical service (INS) S11: > 11 gal/min from at least one faucet (TEST) S12: Equipment works (DEMO)
5. Example
3. Design 57
Contractor Wants
Customer wants Contractor wants
Profit Pride Law
20% Happy buyer Meets code
Contractor requirements
Contractor wants create pseudo requirements in addition to customer requirements. These pseudo requirements can be
considered to be part of the design. In this example, they don’t flow from the customer wants.
5. Example
3. Design 58
Contractor Requirements
Wants Ds1: 20 percent profit (INS) Ds2: Make buyer happy (INS)
Other Dr1: Meets code (INS, DEMO)
5. Example
3. Design 59
Design Process
Preliminarydesignreview
Criticaldesignreview
Develop product concept
Develop product design
concept design
spec &
I/Fs
lower specs & I/FsDevelop
lower specs & interfaces
approval approval
5. Example
3. Design 60
Concept
Garage
Storage Utility
Living
KitchenBedroom Bedroom
MasterBedroom
Bath
Bath
N
5. Example
3. Design 61
Spec Tree
House and lot
Real estate Structure Electrical Plumbing
5. Example
3. Design 62
Contractor Design
Dd1: Plans Floor plan Elevations Plumbing plan Electrical plan Foundation plan Lot layout
Dd2: Flood analysis Dd3: Cost and schedule
5. Example
3. Design 63
Real Estate Flowdown
C2: $100,000C3: close by 6/1/99Ds1: 20%
Dd3: Cost/sched study
Rs2: <$15,000Rs3: close by 1/1/99
Dd1: Plans Dd2: flood analysis
Rr1: milesRr3: 1/2 acreRs1: land
Rr2: doesn’t floodRs4: provide analysis
S02: milesS03: 1/2 acre
S04: doesn’t flood
Product spec, product SOW, and contractor wants flowdown directly and through studies to become the real estate spec and SOW
5. Example
3. Design 64
Real Estate Spec
Rr1: <10 & > 3 miles from town of 5000 people (INS) Rr2: Does not flood (ANA) Rr3: > 1/2 acre (INS)
5. Example
3. Design 65
Real Estate SOW
Rs1: Provide land Rs2: < $15,000 Rs3: Close by 1/1/99 Rs4: Provide flood analysis
5. Example
3. Design 66
Structure FlowdownC2: $100,000C3: close by 6/1/99Ds1: 20%
Dd3: Cost/sched study
Ss2: <$53,000Ss3: close by 5/1/99Ss4: coordinate
Dd1: Plans Dd2: flood analysis
Product spec, product SOW, and contractor wants flowdown through studies to become the structure spec and SOW
Ss1: structureSr1: meets designSr2: brickSr3: roofSr4: paintSr5: carpet
S11: electricalS12: worksDr1: meets codeDs2: buyer happy
Sr6: tileSr7: colorsSr8: tile colorSr9: meets code
5. Example
3. Design 67
Structure Spec
Sr1: Meets design (INS) Sr2: Brick (INS) Sr3: 30-yr composition (INS) Sr4: Long-lasting paint (INS) Sr5: Nylon carpet except bath and kitchen (INS) Sr6: Ceramic tile on all other interior floors (INS) Sr7: White exterior paint, beige interior paint,
beige carpet (INS) Sr8: White tile (INS) Sr9: Meets code (INS)
5. Example
3. Design 68
Structure SOW
Ss1: Provide structure Ss2: <$53,000 Ss3: Compete by 5/1/99 Ss4: Coordinate with plumber and electrician
5. Example
3. Design 69
Electrical Flowdown
C2: $100,000C3: close by 6/1/99Ds1: 20%
Dd3: Cost/sched study
Es2: <$4,000Es3: close by 5/1/99Es4: coordinate
Dd1: Plans Dd2: flood analysis
Product spec, product SOW, and contractor wants flowdown through studies to become the electrical spec and SOW
Es1: electricalEr1: meets designPr2: electricalPr3: meets code
S11: electricalS12: worksDr1: meets code
5. Example
3. Design 70
Electrical Spec
Er1: Meets design (INS) Er2: >100 amperes electrical service (INS) Er3: Meets code (INS)
5. Example
3. Design 71
Electrical SOW
Es1: Provide electrical Es2: <$4,000 Es3: Complete by 5/1/99 Es4: Coordinate with structure
5. Example
3. Design 72
Plumbing Flowdown
C2: $100,000C3: close by 6/1/99Ds1: 20%
Dd3: Cost/sched study
Ps2: <$8,000Ps3: close by 5/1/99Ps4: coordinate
Dd1: Plans Dd2: flood analysis
Product spec, product SOW, and contractor wants flowdown through studies to become the plumbing spec and SOW
Ps1: plumbingPr1: meets designPr2: waterPr3: meets code
S11: waterS12: worksDr1: meets code
5. Example
3. Design 73
Plumbing Spec
Pr1: Meets design (INS) Pr2: >100 gal/min from one faucet (TEST) Pr3: Meets code (INS)
5. Example
3. Design 74
Plumbing SOW
Ps1: Provide plumbing Ps2: <$8,000 Ps3: Complete by 5/1/99 Ps4: Coordinate with structure
5. Example
3. Design 75
6. Other Design Processes
Defense Management College (DMC) design process
James Martin design process EIA-632 design process
6. Other design processes
3. Design 76
DMC Design Process
Requirements analysis
Functional analysis and
allocation
Synthesis
System analysis and
control
requirements loop
design loop
verification
process inputs
process outputs
Systems Engineering Process
6. Other design processes
3. Design 77
James Martin Design Process
Requirements Analysis
Functional Analysis and
Allocation
Synthesis
Requirements loop Design loop
Requirements and architecture
documentation
Verification loop
System analysis and optimization
Specs, interfaces, design
RequirementsProduct characteristics
3. Design 78
EIA 632
Requirements relationship Design Process
Logical solution definition Physical solution definition Specified requirements generation
6. Other design processes
3. Design 79
Requirements Relationship
User or customer requirements
System technical requirements
Logical solution
Physical solution
Derived technical
requirements
Design solution
Specified requirements
Other stakeholder
requirements
TRACE TO
Assigned requirementsTRACE TO
TRACE TO
ASSIGNED TO ASSIGNED TO
ASSIGNED TO
DRIVE
SOURCE OF
SPECIFIED BY
BECOME
The EIA 632 entity relationship is similar to the PBA approach but is more complex.
6. Other design processes
3. Design 80
Design Process
Logical Solution
Definition
Specified Requirements
Generation
Physical Solution
Definition
Specifications, drawings, models
System technical requirements
The EIA 632 design process is quite similar to the product basedapproach given earlier, but it is more serial in description
EIA 632 Figure 4.3.2
6. Other design processes
3. Design 81
Logical Solution Definition (1 of 3)
Analyze functions, objects, data flow, data structures Define subfunctions Perform trade studies Assign performance requirements & constraints Analyze behaviors
6. Other design processes
3. Design 82
Logical Solution Definition (2 of 3)
Identify and define interfaces, states and modes, timelines, data, & and control
Analyze failure modes and define effects
6. Other design processes
3. Design 83
Logical Solution Definition (3 of 3)
Establish set of logical solutions Validate logical solutions Record logical solutions Identify and define derive technical requirements Record derived technical requirements
6. Other design processes
3. Design 84
Physical Solution Definition
Perform system analysis
Define I/Fs
ID & analyze critical
parameters
ID & assess physical solution
options
ID and define technical
requirements
Group requirements & solutions
Assign groups to physical solutions
Generate alternative solutions
Select solution
The physical solution definition is more serial than the PBA.
6. Other design processes
3. Design 85
Specified Requirements Generation
Fully characterize design solution Verify design solution Record design solution Generate and record specified requirements Initiate development of enabling processes
6. Other design processes
3. Design 86
7. Homework
A customer wants to sell a line of lawn mowers that can cut Texas lawn grasses, requires partial assembly, and that costs less than $300
Develop a design that satisfies the customer 1. List the customer requirements (>0, <10) 2. List pseudo customer requirements (0, <20) 3. List the key items in the concept (>0, <20) 4. List the key items in the design (>0, <20) 5. List key items in documentation (>0, <20) 6. List the key items in the CDR (>0, <20) 7. List items shall be (>0, <30 words); no pictures
7. Homework