Transcript Display - Edge - Rochester Institute of Technology

Functional Decomposition
Design Project Management
Rochester Institute of Technology
Mechanical Engineering Department
Rochester, NY USA
R .I . T
Mechanical Engineering
Purpose of the functional decomposition:
• Identify a small number of functions (the WHAT) that your
product must deliver to the customer to satisfy their need
(the WHY)
• Prepare to map those functions back to customer
needs.
• As long as you provide the correct “WHAT” to your customer, they
will often not care “HOW” you deliver the functions.
• Modularize the product
• Provide a structure around which to specify the problem
• Provide a structure around which to brainstorm
• We will try two different approaches today – both may
have value for your team!
R .I . T
Mechanical Engineering
What is the core function?
• What is the one core function that the
device/product/process needs to
accomplish?
• What subfunctions need to be performed
in order to achieve that function?
• This allows you to begin distinguishing your
problem/solution from others.
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Mechanical Engineering
Navigate an individual from Point
A to Point B, given A and B (start
and end points) and information
about the surrounding environment
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Mechanical Engineering
Inputs and Outputs?
• Flow through the system that is
performing this function
• Information
• Matter
• Energy
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Mechanical Engineering
On Map?
Region Map
Hardware Health
Nearest Tag ID(s)
Destination
Navigate an individual from Point
A to Point B, given A and B (start
and end points) and information
about the surrounding environment
Movement Instructions
ETA
Power
R .I . T
Heat
Mechanical Engineering
How are you going to perform that
function?
• Verb-Noun
• Examples:
• Identify current location/state
• Identify destination
• Determine route
• How is that information, matter, or energy
being transformed or moved through the
system?
R .I . T
Mechanical Engineering
Navigate an individual from Point A to Point B,
given A and B (start and end points) and information
about the surrounding environment
Identify
current
state
R .I . T
Identify
target
state
Determine
Route
Transmit
information
to user
Support
internal
components
Mechanical Engineering
Region Map
Identify
current
state
Determine
Route
Nearest Tag ID(s)
Destination
Power
On Map?
Identify
target
state
Transmit
information
to user
Movement Instructions
ETA
Battery,
MCU
Hardware Health
Heat
R .I . T
Mechanical Engineering
How are you going to do THAT?
• How are you going to identify current
state?
• Identify current location
• Identify current orientation
R .I . T
Mechanical Engineering
Navigate an individual from Point A to Point B, given
A and B (start and end points) and information about
the surrounding environment
Identify Current State
Identify
Target
State
Identify
Current
Location
Accept User
Input
R .I . T
Identify
Current
Orientation
Import Map
Determine
Route
Calculate path
Calculate next
movement
instruction
Transmit
Info to
User
Convert
movement
instruction to
tactile
feedback
Support & Manage
Internal Components
Support
components
Maintain
Temperature
Protect
Components
Store Power
Accept
Charging
Power
Regulate
Power
Mechanical Engineering
Or: Brainstorm a list of tasks, then
sort
• Sort tasks into hierarchical order
• Ask how you will complete each task
• Ask why you must complete each task
Navigate an individual from Point A to Point B, given A
and B (start and end points) and information about the
surrounding environment
Identify
Current
State
Ask “why”
R .I . T
Identify
Current
Location
Identify
Current
Orientation
Import Map
Identif
y
Target
State
Accept
User Input
Determine
Route
Calculate
path
Calculate
next
movement
instruction
Transmit
Info to
User
Convert
movement
instruction
to tactile
feedback
Support &
Manage
Internal
Components
Support
component
s
Maintain
Temperatur
e
Protect
Component
s
Ask “how”
Store
Power
Accept
Charging
Power
Regulate
Power
Mechanical Engineering
Receive
Map Info
Compare
current to map
Record
location
history
Nearest Tag
ID(s)
ID current
location
(RFID)
Navigation
Loop
Destination
Receive
User Input
Magnetic
Field
Determine
Orientation
(Compass)
Charging
Power
Store onboard
Power
On Map?
Calculate
Velocity
Calculate
ETA
Calculate
path
Calculate next
movement
instruction
Monitor Hardware
Health
Deliver Information to User
Region Map
ETA
Movement
Instructions
Hardware
Health
(MCU: Define Interfaces
with Power, User Input,
Map Input, RFID Reader,
Compass, Output Drive
Circuitry)
Regulate
Power
Heat
Enclosure: Support & Manage
Internal Components
R .I . T
Mechanical Engineering
Receive
Map Info
Record
location
history
Information
Nearest Tag
ID(s)
ID current
location
(RFID)
Navigation
Loop
Destination
Receive
User Input
Magnetic
Field
Determine
Orientation
(Compass)
Charging
Power
Energy
Compare
current to map
Store onboard
Power
On Map?
Calculate
Velocity
Calculate
ETA
Calculate
path
Calculate next
movement
instruction
Monitor Hardware
Health
Deliver Information to User
Region Map
ETA
Movement
Instructions
Hardware
Health
(MCU: Define Interfaces
with Power, User Input,
Map Input, RFID Reader,
Compass, Output Drive
Circuitry)
Regulate
Power
Heat
Enclosure: Support & Manage
Internal Components
R .I . T
Mechanical Engineering
Consider last week’s example…
• I said, “We need a better ladder”.
• What if I had said, “We need a device that
provides access to objects above human
reach”?
• Core fuction: Provide access to objects above
human reach.
• Define problem further in the subfunctions
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Mechanical Engineering
Point of Confusion #1
• Functions ≠ Constraints
• Constraints are system-wide parameters, like cost,
weight, overall footprint
• Functions are actions, what your device/system will
do (verb-noun)
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Mechanical Engineering
Point of Confusion #2
• Engineering Metrics and Target
Specifications define how well you need
to perform these functions/subfunctions,
or what constraints you must meet
• Metrics = what to measure, units
• Specifications = magnitude
• Consider specifications for minimally acceptable,
target, and ideal conditions
R .I . T
Mechanical Engineering
Examples of Functions
• Some functions that your product may perform
(from Otto & Wood Product Design):
• Import, export, transfer, transmit, guide, translate,
rotate, allow degrees of freedom
• Stop, stabilize, secure, position
• Couple, mix, separate, remove, refine, distribute,
dissipate
• Store, supply, extract
• Actuate, regulate, change, form, condition
• Sense, indicate, display, measure
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Mechanical Engineering
In-Class Example
• Develop a functional decomposition for a
device that will enable a person with
one hand to secure their hair in a
ponytail.
• R13002, R13201, and R13301 use
function tree/FAST diagram
• R13401, R13701, and R13904 use flow
diagram
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Mechanical Engineering
Regroup
• Two teams share function trees
• Discussion:
•
•
•
•
•
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How are these different from yours?
Is one right or wrong? Better or worse?
Are you (or they) missing functions?
Are you (or they) prescribing solutions?
Other questions?
Mechanical Engineering
Questions?
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Mechanical Engineering
Rest of Today…
• Refine VOC, problem background
• Feedback from guide
• Follow-up with stakeholders
• Prepare for next week’s presentation
• What information do you want to convey?
• What information are you still missing?
• Begin considering core function(s) for
your project(s)
R .I . T
Mechanical Engineering
Next Steps
• Assign metrics and specifications
• Metrics = what to measure, units
• Specifications = magnitude
• Consider specifications for minimally acceptable,
target, and ideal conditions
• Performance Specifications: what the
customer sees
• Design Specifications: define interfaces
R .I . T
Mechanical Engineering
R .I . T
Mechanical Engineering
Specifications:
Metrics and Target Values
Design Project Management
R .I . T
Mechanical Engineering
When we left off…
• Functional decomposition
• Function Tree
• Flow Diagram
• Each product development team should
have a draft functional decomposition by
now
R .I . T
Mechanical Engineering
Context
• Objective Tree: What the customer needs
• Function Tree: How the overall project
goal will be achieved
• Specifications: How well do the functions
need to be performed?
R .I . T
Mechanical Engineering
Metrics and Specifications
• Indicate units of measure (metrics)
• Indicate preferred direction
•
•
•
•
•
•
Up, maximize
Down, minimize
Target value
Range or list of values
Binary
Survey results
• Min. acceptable, target, and ideal values
R .I . T
Mechanical Engineering
How do we define specifications?
• Benchmarks
• You should already have identified some benchmark
products
• Analysis
• You should already have identified relevant
governing equations, course material, etc.
• Stakeholder requirements
• Business goals, must interface with existing system,
stakeholder characteristic, etc.
R .I . T
Mechanical Engineering
Example #1: RC Camera Car
R .I . T
Mechanical Engineering
How will you measure a “good job”?
Function
Metric (s)
Convert input to wireless
Transmit control signal to car
Convert signal to mechanical response
Power components
Protect components
R .I . T
Mechanical Engineering
How will you measure a “good job”?
Function
Metric [direction]
Convert input to wireless
Delay time (msec)
Transmit control signal to car
Transmit range (m), transmit rate (bytes/sec)
Convert signal to mechanical response
Delay time (msec), sensitivity (deg/deg, N/N, ...)
Power components
Voltage (V), current (A), time between charges (h)
Protect car components
Max collision speed (m/s)
Protect console components
Max drop height (m)
Metrics
R .I . T
Mechanical Engineering
What is the “good job” threshold?
• Ideal
• Reach goal
• Target
• What you can reasonably expect to achieve
• Marginal
• Performance barely acceptable to customer
Specifications
R .I . T
Mechanical Engineering
How will you measure a “good job”?
Function
Metric [direction]
Convert input to wireless
Delay time (msec) [↓]
Transmit control signal to
car
Transmit range (m) [↑]
transmit rate (bytes/sec) [↑]
Convert signal to
mechanical response
Delay time (msec) [↓]
sensitivity (deg/deg, N/N, ...)
Power components
Voltage (V), current (A)
time between charges (h) [↑]
Protect car components
Max collision speed (m/s) [↑]
Protect console
components
Max drop height (m) [↑]
R .I . T
Target
Marginal
Mechanical Engineering
How will you measure a “good job”?
Function
Metric [direction]
Convert input to wireless
Delay time (msec) [↓]
Transmit control signal to
car
Transmit range (m) [↑]
transmit rate (bytes/sec) [↑]
Convert signal to
mechanical response
Delay time (msec) [↓]
sensitivity (deg/deg, N/N, ...)
Power components
Voltage (V), current (A)
time between charges (h) [↑]
Protect car components
Max collision speed (m/s) [↑]
Protect console
components
Max drop height (m) [↑]
Target
Marginal
30 m
1500 kbps
10 m
500 kbps
1m
0.1 m
Specifications
R .I . T
Mechanical Engineering
How to define values for specs?
•
•
•
•
Benchmark products (by function)
Spec sheets
Customer criteria
Basic feasibility analysis
• Remember: there may be dependency
between specs! Learn more when we
cover House of Quality
R .I . T
Mechanical Engineering
Reflect on the Process
• Do the results make sense?
• Are all the functions/specs appropriate?
• Are you willing/able to do the test to get the
measurement (e.g., destructive testing, infinite life
testing)?
• Have all the functions been captured?
• Is there an expected performance metric that doesn’t
show up? Could mean you missed a function!
R .I . T
Mechanical Engineering
Remainder of hour (if time)
• For each of your functions, determine:
• Metric(s)
• Source for target value (observation, measurement,
analysis, research, benchmark, etc.)
• Direction you want to drive the value (up, down,
target, etc.
• Is the function appropriate?
R .I . T
Mechanical Engineering
Brainstorming
Design Project Management
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Mechanical Engineering
Why?
• How often is the first idea to come to
mind the best possible solution?
• Are you looking for incremental
improvements or significant change?
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Mechanical Engineering
When?
• After you’ve decomposed your problem
into a series of functions
• Manageable pieces
• Easy to brainstorm ways to perform a single function
• When creative ideas are sought
• This is NOT always the case
• Ask yourself, “Does it make sense?”
• Example: Navigation Aid for Blind User
R .I . T
Mechanical Engineering
Receive
Map Info
Compare
current to map
Record
location
history
Nearest Tag
ID(s)
ID current
location
(RFID)
Navigation
Loop
Destination
Receive
User Input
Magnetic
Field
Determine
Orientation
(Compass)
Charging
Power
Store onboard
Power
On Map?
Calculate
Velocity
Calculate
ETA
Calculate
path
Calculate next
movement
instruction
Monitor Hardware
Health
Deliver Information to User
Region Map
ETA
Movement
Instructions
Hardware
Health
(MCU: Define Interfaces
with Power, User Input,
Map Input, RFID Reader,
Compass, Output Drive
Circuitry)
Regulate
Power
Heat
Enclosure: Support & Manage
Internal Components
R .I . T
Mechanical Engineering
Compare
current to map
Record
location
history
Nearest Tag
ID(s)
ID current
location
(RFID)
Navigation
Loop
Destination
Receive
User Input
Magnetic
Field
Determine
Orientation
(Compass)
Charging
Power
Store onboard
Power
On Map?
Calculate
Velocity
Calculate
ETA
Calculate
path
Calculate next
movement
instruction
Monitor Hardware
Health
Deliver Information to User
Region Map
Receive
Map Info
Pre-defined
solution, or
heavily
constrained
ETA
Movement
Instructions
Hardware
Health
(MCU: Define Interfaces
with Power, User Input,
Map Input, RFID Reader,
Compass, Output Drive
Circuitry)
Regulate
Power
Heat
Enclosure: Support & Manage
Internal Components
R .I . T
Mechanical Engineering
Compare
current to map
Record
location
history
Nearest Tag
ID(s)
ID current
location
(RFID)
Navigation
Loop
Destination
Receive
User Input
Magnetic
Field
Determine
Orientation
(Compass)
Charging
Power
Store onboard
Power
On Map?
Calculate
Velocity
Calculate
ETA
Calculate
path
Calculate next
movement
instruction
Monitor Hardware
Health
Deliver Information to User
Region Map
Receive
Map Info
ETA
Pre-defined
solution, or
heavily
constrained
Limited
opportunities for
creative problem
solving
Movement
Instructions
Hardware
Health
(MCU: Define Interfaces
with Power, User Input,
Map Input, RFID Reader,
Compass, Output Drive
Circuitry)
Regulate
Power
Heat
Enclosure: Support & Manage
Internal Components
R .I . T
Mechanical Engineering
Compare
current to map
Record
location
history
Nearest Tag
ID(s)
ID current
location
(RFID)
Navigation
Loop
Destination
Receive
User Input
Magnetic
Field
Determine
Orientation
(Compass)
Charging
Power
Store onboard
Power
On Map?
Calculate
Velocity
Calculate
ETA
Calculate
path
Calculate next
movement
instruction
Monitor Hardware
Health
Deliver Information to User
Region Map
Receive
Map Info
ETA
Limited
opportunities for
creative problem
solving
Movement
Instructions
Hardware
Health
Good opportunity to
seek creative
solutions
(MCU: Define Interfaces
with Power, User Input,
Map Input, RFID Reader,
Compass, Output Drive
Circuitry)
Regulate
Power
Pre-defined
solution, or
heavily
constrained
Heat
Enclosure: Support & Manage
Internal Components
R .I . T
Mechanical Engineering
Approaches & Tools
• Many!
• Some example from Otto & Wood
Product Design:
•
•
•
•
R .I . T
Mind Maps
6-3-5 method
Analogies
Separate by physical principles
Mechanical Engineering
Rules (IDEO)
• Designate a
moderator
• Defer judgment
(moderator)
• Encourage wild ideas
• Build on ideas of
others (OK to steal
ideas)
• Stay focused
(moderator)
• One conversation at a
time
• Use pictures
• Quantity over quality
• There are no experts
• Democracy is bad
• Boss doesn’t go first
• Relaxed environment
+ food help
IDEO video: http://youtu.be/M66ZU2PCIcM
R .I . T
Mechanical Engineering
6-3-5 Method
• Teams sit in circles
• Each team member draws or writes down 3 ideas on a
piece of paper (3 minutes)
• Pass paper to the left
• For 1 minute, make comments, additions, sketches on
the paper in front of you
• Repeat 4 more times (5 turns, total)
R .I . T
Mechanical Engineering
Analogies
• Identify an element of nature that
performs a function analogous to the one
you are charged with.
• Develop concept(s) based on those
elements of nature.
R .I . T
Mechanical Engineering
Search by Physical Principles
• For each function, consider the physical principles that
could govern it. For example, you can store energy in
several different ways (example from Otto & Wood):
• Mechanical
• Electrical
• Chemical
R .I . T
Mechanical Engineering
Example #2: PMTR
R .I . T
Mechanical Engineering
Example: Solution-Independent!
Deformed
sample
User
actuation
Convert input to
displacement
Type of test (F
or d control)
Test
sample
Apply
displacement to
sample
Accept test
sample
Secure test
sample
Measure
Force
Measure
displacement
Force
value
Displacement
value
Disclaimer: not a perfect functional decomposition,
but a step toward solution-independence!
R .I . T
Mechanical Engineering
Brainstorm
Deformed
sample
User
actuation
Convert input to
displacement
Type of test (F
or d control)
Test
sample
R .I . T
Apply
displacement to
sample
Accept test
sample
Secure test
sample
Measure
Force
Measure
displacement
Force
value
Displacement
value
Mechanical Engineering
Take 15 minutes
• Boeing, Library: Physical principle
• Assistive Technology, AQM: 6-3-5
• Test Rigs, Student-Initiated: Analogy
R .I . T
Mechanical Engineering
Discussion, questions?
•
•
•
•
•
•
R13002: 61 ideas/6 people
R13201: 52 ideas/8 people
R13301: 25 ideas/5 people
R13401: 49 ideas/9 people
R13701: 44 ideas/6 people
R13904: 38 ideas/3 people (12.6 ideas/team member)
R .I . T
Mechanical Engineering