Download Requirements and Selection

Requirements
Requirements – Essential To Robust Product Design
Definition: “Statements of desired product performances and
features used to define and quantify a product design”
• User Level: Special list or labels which state the intended
application and/or purpose of the product (Labeling)
• Product Level: (System Level) Quantitatively state all
features, performances, and interfaces in “Eng Terms”
• Block Level: State all features, performances and interfaces
describing the block in “Engineering Terms”
– User Level >>> Validation
– Product & Block Level>>>Verification
Efficient Engineering teams fully specify before they design !!
Requirements
Requirements Imply Proof of Satisfaction !
Implied Product Design Integrity !
• Many Gov’t Agencies mandate that ALL product
requirements should be user validated and/or engineering
verified (tested or justified). A requirement which cannot be
verified or validated should not be stated unless objective
evidence can be compiled to prove its satisfaction
• Requirement Categorization Used in this Course:
– Standard: Common to ALL Project Teams
– Performance: Unique to Project and Technology, For Differentiating
Requirements
Design Blocks
• Complex products require that the design be broken into
logical design elements (termed blocks in this course)
• Min 1 Design Block per team member is Mandatory
• Blocks form the basis of standardized design elements in this
course.
• The terms Product and System are used interchangably
• Product Level Requirements can either be allocated or just
associated to all design blocks.
• The Project System Design entails defining ALL Block
Performance Reqs incl Interfaces and Functions
Requirements
Allocation and Association
to Design Blocks
• ALL Product Level Requirements Must be
allocated or associated to each Design Block within
the project to complete a System Design Phase
– Allocated: % of total budgeted to applicable design
blocks plus margin. For example: Product Cost, Power
Consumption, Mass ….
– Associated: Used when allocation is not applicable. For
example: Country(s) of Market, Annual Volume, Safety
Standards ….
Requirements
Product Level - Standard Requirements
• Standard Requirements are those requirements which are
universal and can be applied to nearly all products and hence
final projects
• Standard Requirements may or may not be differentiating
depending upon project goals but MUST be part of the
minimum description of the product
Standard Reqs Are Common to Nearly ALL Projects
Requirements
System - Std Reqs: Market & Business Case
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Requirement
Competitors
Market Size
Average List Price
Market Geography
Market Demography
Intended Application
Material Cost
Manufacturing Cost
Annual Volume
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Units to Specify
Company Name(s), Model#(s)
Total $/Region, Info Source
$/unit as sold to customers
List of Countries or Regions
Min/Max Age, Sex, Restrictions
Ind, Auto, Home, Wearable, etc
$/unit in volume production
$/unit in volume production
# of units/yr
Choose & Understand your Market “before”
…………. you design a product
Requirements
System - Std Reqs: Env & Safety
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Requirement
Min Oper Temp Range
Min Oper Humidity Range
Min Oper Alt or Press Range
Min Storage Temp Range
Min Storage Humidity Range
Min Storage Alt or Press Range
Max Storage Duration
Primary EMC Standards
Primary Safety Standards
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Units to Specify
Co Range
Rh% Range
Meters or ATM, Range
Co Range
Rh% Range
Meters or ATM, Range
Time in Days or Years
List of IEC or FCC stds
List UL, IEC or other stds
Consider Simultaneous Min or Max Cases
Some will NOT be “testable”
Requirements
System - Std Reqs: Power Interfaces
Requirement
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Energy Source List
Source Connection List
Min Oper Voltage Range
Max Power Consumption
Max Energy Consumption
Units to Specify
• AC, Auto Batt, Photovoltaic,
Dedicated Batt, Generator, Fuel Cell, etc
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Permanent or Temporary
Voltage Range, For each Source
Watts Total, For each Source
Watt-Hours/Yr for AC Power,
Calander Life Time for Batteries
Must consider power source(s) early
Undefined DC power sources NOT allowed
Requirements
System - Std Reqs: Mechanical
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Requirement
Max Volume
Shipping Container Size
Max Mass
Elec I/F Connector(s)
Max # of PC Bds
Max PCB Circuit Area
Max Shock
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Units to Specify
Cm3 Total for Entire Product
Cm Max LxWxH for 1 unit
Kilograms
Type or Style
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Cm2 Total
G force (Grms), # Reps
Package and Mechanical Design Impact
Many Product Aspects
Requirements
System - Std Reqs: Mfg & Life Cycle
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Requirement
Max Parts Count
Max Unique Parts Count
Parts/Mat $ Allocation
Asm/Test $ Allocation
Product Life, Reliability
Full Warranty Period
Product Disposition
Production Life Support
Service Strategy
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# Total Parts incl elec & mech
# of Unique Parts
$ (Parts+Mfg=Product Cost)
$ (Parts+Mfg=Product Cost)
Time = MTBF(yrs)
Time (yrs)
Return, Recycle, Dispose, etc
Time (yrs)
Dispose or Repair, Factory or Field
Product designs should consider full “life
cycle” from Mfg process to Disposal
Requirements
System - Performance Requirements
• Performance Requirements are those requirements which are
specific to a product and project
• Performance Requirements differentiate the product from all
other similar products
• Performance Requirements should describe ….
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Signal Interfaces
Mechanical Interfaces
Features, Options
Modes of Operation
Performance Parameters
User Controls
User Displays and Outputs
Requirements
System – Perf Reqs: Power Input(s)
(Must be Considered if Applicable)
Requirement
• AC Power Freq Range(s)
Definition
• Hz, Range
• AC Power EMC Stds
• EFT, Surge, Dropout, etc
• Battery Chemistry
• Pb-Acid, Li, NMh, Alk, etc
• Battery Std Size
• CR2032, C, D, AA, etc
• Battery Capacity
• Min mA-Hrs
All Applicable Must Be Defined
Requirements
System – Perf Reqs: Electrical Functions
(Must be Defined if Applicable)
Requirement
• Analog Functions
• Digital Functions
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Definition
Voltage or Current Gain
Ranges
Input – Output SNR
Frequency Response
Linearity and THD
Delay in uSec or mSec
Computation or Algorithm
Compute Speeds in Ops/Sec
Input – Output Delay
There may be others to Add
Requirements
System – Perf Reqs: Electrical Interfaces
(For each signal “grouping”)
Electrical Signal Req
• Signal Type
• Signal Direction
• Standard Definition
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• Basic Analog Characteristics
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• Detailed Analog Characteristics
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Definition
Analog, Digital, or Power
Input, Output, Bidirectional
RS170 Video, RS232, USB,
Custom, etc
Voltage Range, Frequency or
Bandwidth Range
Impedance or Current Range
Offset Voltages, Currents
Error Voltages, Currents
Max Noise
Other Analog Characteristics
Every Signal Needs to be Defined in Detail
Requirements
System – Perf Reqs: Electrical Interfaces
(For each signal “grouping”)
Electrical Signal Req
• Digital Input Type
• Digital Output Type
• Basic Digital Characteristics
• Detailed Digital Characteristics
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Definition
Std, Schmitt Trigger
Std, TriState, Open Collector
Outputs: Voh, Vol, Ioh, Iol
Inputs: Vih, Vil, Iih, Iil, Vth
Bidirect: Both
Hi Z Leakage Currents
Min Transition Times
Min Setup & Hold Times
Max Frequency
CANNOT use “TTL” or “CMOS” as Definition
Requirements
System – Perf Reqs: Operator I/F Outputs
(Must be Considered if Applicable)
Requirement
Definition
• Optical Indicators, Lights
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Type, Size, Visibility, Speed, Color,
Lumens
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7 Segment, Matrix, LCD
Total Char/Row, Total Rows
Total Size HxW
Daylight LCD, BLLCD, LED, EL, etc
• Screen Type
• Screen Min X Resolution
• Screen Min Y Resolution
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CRT, TFT Panel,
768, 1024, 1280, etc
512, 768, 1024, etc
• Mechanical Indicators
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Volume, Pitch, Duration, Vibration,
Flags, Other
Display Type
Display Char Matrix
Display Size
Display Illumination
All Applicable Must Be Defined
Requirements
System – Perf Reqs: Operator I/F Inputs
(Must be Considered if Applicable)
Requirement
Definition
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Toggle, Slide, Mom Push, DIP, etc
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Matrix or Ind Key Switches
Total Columns, Total Rows
Total Size HxW
Layout, Functions, Labels
Keyboard Type
Keyboard I/F
Keyboard Total keys
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QWERTY, QWERTY w/Keypad
USB, IBM 5 Pin, RS232, etc
Number of Keys
Analog Dials
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Range of Input
Number of Turns
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Switch Type
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Keypad Type
Keypad Matrix
Keypad Size
Key Definitions
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All Applicable Must Be Defined
Requirements
System – Perf Reqs: Mech Interfaces
(Must be Considered if Applicable)
Requirement
• Mounting
Definition
• Feet, Brackets, Clamps, etc
• Carry Handles
• None, Grips, Bars, etc
• Sensory
• Temp, Pressure, Humidity,
RPM, Acceleration, Dist, etc
• Sub D, IEC-320, USB, etc
• Connectors
Others May Apply
Requirements
System – Perf Reqs: Modes of Operation
(Must be Considered if Applicable)
Requirement
• Power Modes
Definition
• ON/OFF, ON/AC,
ON/Battery, etc
• Power Saving Modes
• Standby, Idle, etc
• Calibration Modes
• Program, Configure, etc
• Service Modes
• Diagnostic, Test, etc
Others May Apply
Requirements
Compare Your Possible Projects
Project Recommendation
Reqs
3 Possible Proj
Brain Storm Ideas
Down Select Your Project Ideas:
• Interest:
– Does the project hold interest for ALL team members?
– Can you identify similar products in the market?
– How unique is the project compared to previous capstone projects?
• Block Diagram:
– Do the project blocks best match the skills and resources available on the
team?
– Does the block diagram contain at least 1 robust design block for each
team member?
– Is the block diagram overly complex
Requirements
Compare Your Possible Projects
Project Recommendation
Reqs
3 Possible Proj
Brain Storm Ideas
Down Select Your Project Ideas:
• System Perf Requirements:
– Can you list the key differentiating performance requirements which
would create market demand?
– Are you able to quantify the key system performance requirements?
• System Std Requirements:
– Can you quantify ALL the system standard requirements?
– Can you allocate applicable system standard requirements to ALL blocks?
Requirements
Compare Your Possible Projects
Project Recommendation
Reqs
3 Possible Proj
Brain Storm Ideas
Down Select Your Project Ideas:
• Prototype and Resources:
– How difficult will it be to construct a prototype to demonstrate the
primary functionality and performances?
– Is the project dependent upon any development tools which may be
difficult to procure or gain access to utilize?
– Does the prototype depend on key components with lead times that could
exceed the project timing requirements such as sensors, displays and
transducers?
– Does the available financial resource match the estimated cost of the
prototype?