R. I. T Mechanical Engineering Functional Decomposition Design Project Management Rochester...
-
Upload
brook-ross -
Category
Documents
-
view
219 -
download
1
Transcript of R. I. T Mechanical Engineering Functional Decomposition Design Project Management Rochester...
R . I . TMechanical Engineering
Functional Decomposition
Design Project Management
Rochester Institute of TechnologyMechanical Engineering Department
Rochester, NY USA
R . I . TMechanical 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 . TMechanical 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.
R . I . TMechanical Engineering
Navigate an individual from Point A to Point B, given A and B (start and end points) and information
about the surrounding environment
R . I . TMechanical Engineering
Inputs and Outputs?
• Flow through the system that is performing this function• Information• Matter• Energy
R . I . TMechanical Engineering
Navigate an individual from Point A to Point B, given A and B (start and end points) and information
about the surrounding environment
Region Map
Nearest Tag ID(s)
Destination
Power
On Map?
Hardware Health
Movement Instructions
ETA
Heat
R . I . TMechanical 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 . TMechanical 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
Determine Route
Transmit information
to user
Support internal
components
R . I . TMechanical Engineering
Region Map
Nearest Tag ID(s)
Destination
Power
On Map?
Hardware Health
Movement Instructions
ETA
Identify current state
Identify target state
Determine Route
Transmit information
to user
Heat
Battery, MCU
R . I . TMechanical Engineering
How are you going to do THAT?
• How are you going to identify current state?• Identify current location• Identify current orientation
R . I . TMechanical Engineering
R . I . TMechanical 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
Ask “how”
Ask “why”
R . I . TMechanical Engineering
Region Map
Nearest Tag ID(s)
Destination
Charging Power
On Map?
Hardware Health
Movement Instructions
ETA
Receive Map Info
Record location history
Regulate Power
Enclosure: Support & Manage Internal Components
Receive User Input
Calculate path
Determine Orientation (Compass)
ID current location (RFID)
Compare current to map
Calculate next movement instruction
Calculate Velocity
Calculate ETA
Monitor Hardware Health
(MCU: Define Interfaces with Power, User Input,
Map Input, RFID Reader, Compass, Output Drive
Circuitry)Store on-
board Power
Navigation Loop
Heat
Magnetic Field
R . I . TMechanical Engineering
Region Map
Nearest Tag ID(s)
Destination
Charging Power
On Map?
Hardware Health
Movement Instructions
ETA
Receive Map Info
Record location history
Regulate Power
Enclosure: Support & Manage Internal Components
Receive User Input
Calculate path
Determine Orientation (Compass)
ID current location (RFID)
Compare current to map
Calculate next movement instruction
Calculate Velocity
Calculate ETA
Monitor Hardware Health
(MCU: Define Interfaces with Power, User Input,
Map Input, RFID Reader, Compass, Output Drive
Circuitry)Store on-
board Power
Navigation Loop
HeatEnergy
Information
Magnetic Field
R . I . TMechanical 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
R . I . TMechanical 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)
R . I . TMechanical 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 . TMechanical 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
R . I . TMechanical 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
R . I . TMechanical Engineering
Regroup
• Two teams share function trees
• Discussion:• 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?
R . I . TMechanical Engineering
Questions?
R . I . TMechanical 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 . TMechanical 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 . TMechanical Engineering
R . I . TMechanical Engineering
Specifications:Metrics and Target Values
Design Project Management
R . I . TMechanical 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 . TMechanical 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 . TMechanical 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 . TMechanical 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 . TMechanical Engineering
Example #1: RC Camera Car
R . I . TMechanical 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 . TMechanical 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 . TMechanical 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 . TMechanical Engineering
How will you measure a “good job”?
Function Metric [direction] Target Marginal
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 . TMechanical Engineering
How will you measure a “good job”?
Function Metric [direction] Target Marginal
Convert input to wireless Delay time (msec) [↓]
Transmit control signal to car
Transmit range (m) [↑]transmit rate (bytes/sec) [↑]
30 m1500 kbps
10 m500 kbps
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) [↑] 1 m 0.1 m
Specifications
R . I . TMechanical 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 . TMechanical 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 . TMechanical 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 . TMechanical Engineering
Brainstorming
Design Project Management
R . I . TMechanical 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?
R . I . TMechanical 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 . TMechanical Engineering
Region Map
Nearest Tag ID(s)
Destination
Charging Power
On Map?
Hardware Health
Movement Instructions
ETA
Receive Map Info
Record location history
Regulate Power
Enclosure: Support & Manage Internal Components
Receive User Input
Calculate path
Determine Orientation (Compass)
ID current location (RFID)
Compare current to map
Calculate next movement instruction
Calculate Velocity
Calculate ETA
Monitor Hardware Health
(MCU: Define Interfaces with Power, User Input,
Map Input, RFID Reader, Compass, Output Drive
Circuitry)Store on-
board Power
Navigation Loop
Heat
Magnetic Field
R . I . TMechanical Engineering
Region Map
Nearest Tag ID(s)
Destination
Charging Power
On Map?
Hardware Health
Movement Instructions
ETA
Receive Map Info
Record location history
Regulate Power
Receive User Input
Calculate path
Determine Orientation (Compass)
ID current location (RFID)
Compare current to map
Calculate next movement instruction
Calculate Velocity
Calculate ETA
Monitor Hardware Health
(MCU: Define Interfaces with Power, User Input,
Map Input, RFID Reader, Compass, Output Drive
Circuitry)Store on-
board Power
Navigation Loop
Heat
Magnetic Field
Enclosure: Support & Manage Internal Components
Pre-defined solution, or
heavily constrained
R . I . TMechanical Engineering
Region Map
Nearest Tag ID(s)
Destination
Charging Power
On Map?
Hardware Health
Movement Instructions
ETA
Receive Map Info
Record location history
Regulate Power
Receive User Input
Calculate path
Determine Orientation (Compass)
ID current location (RFID)
Compare current to map
Calculate next movement instruction
Calculate Velocity
Calculate ETA
Monitor Hardware Health
(MCU: Define Interfaces with Power, User Input,
Map Input, RFID Reader, Compass, Output Drive
Circuitry)Store on-
board Power
Navigation Loop
Heat
Magnetic Field
Enclosure: Support & Manage Internal Components
Pre-defined solution, or
heavily constrained
Limited opportunities for creative problem
solving
R . I . TMechanical Engineering
Region Map
Nearest Tag ID(s)
Destination
Charging Power
On Map?
Hardware Health
Movement Instructions
ETA
Receive Map Info
Record location history
Regulate Power
Receive User Input
Calculate path
Determine Orientation (Compass)
ID current location (RFID)
Compare current to map
Calculate next movement instruction
Calculate Velocity
Calculate ETA
Monitor Hardware Health
(MCU: Define Interfaces with Power, User Input,
Map Input, RFID Reader, Compass, Output Drive
Circuitry)Store on-
board Power
Navigation Loop
Heat
Magnetic Field
Enclosure: Support & Manage Internal Components
Pre-defined solution, or
heavily constrained
Limited opportunities for creative problem
solving
Good opportunity to seek creative
solutions
R . I . TMechanical Engineering
Approaches & Tools
• Many!
• Some example from Otto & Wood Product Design:• Mind Maps• 6-3-5 method• Analogies• Separate by physical principles
R . I . TMechanical Engineering
Rules (IDEO)
IDEO video: http://youtu.be/M66ZU2PCIcM
R . I . TMechanical 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 . TMechanical 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 . TMechanical Engineering
• 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
Search by Physical Principles
R . I . TMechanical Engineering
Example #2: PMTR
R . I . TMechanical Engineering
Example: Solution-Independent!
User actuation Convert input to
displacement
Type of test (F or d control)
Test sample Accept test
sampleSecure test
sample
Measure Force
Measure displacement
Deformed sample
Force value
Displacement value
Apply displacement to
sample
Disclaimer: not a perfect functional decomposition, but a step toward solution-independence!
R . I . TMechanical Engineering
Brainstorm
User actuation Convert input to
displacement
Type of test (F or d control)
Test sample Accept test
sampleSecure test
sample
Measure Force
Measure displacement
Deformed sample
Force value
Displacement value
Apply displacement to
sample
R . I . TMechanical Engineering
Take 15 minutes
• Boeing, Library: Physical principle
• Assistive Technology, AQM: 6-3-5
• Test Rigs, Student-Initiated: Analogy
R . I . TMechanical 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)