I07 IPPD Step Two Define the Problem

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I07:
Define the Problem:
Requirements & Functional Analysis; Quality Function Deployment (QFD)
Dr. Daniel P. Schrage
Course Instructor and Professor, School of Aerospace Engineering
Georgia Tech
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Define the Problem
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Presentation Outline
Requirements Analysis
Functional Analysis and Decomposition
Quality Function Deployment (QFD)
Relevant Examples
Lab Exercise for Students to Define the Problem for Wing Redesign of a Commercial transport Wing
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Understanding Requirements through Requirements Analysis
Requirements In Context
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Requirements Analysis Questions
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Attributes of a Well-Defined Requirement
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Mission Analysis
Objectives:
Determine problem / opportunity
Identify potential customers and stakeholder
Collect high-level “desirements”
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Describe the events and/or customer input indicating that a problem exists or a change is desired.
Formulate a clear mission or objective statement of the desired change or the problem being addressed.
Establish the mission objective(s) and driving requirements for the project.
Define the Technical Performance Measures (TPMs) that will be used in measuring progress towards programmatic and system objectives.
Identify the scope of the change and initial system hierarchy (system of systems).
Define the system under consideration and the boundaries between it and other related systems.
Identify the initial high level requirements set that should include expectations, requirements, issues, constraints, assumptions, and assertions (ERICAA) regarding the system and project under consideration.
Collect, disseminate and manage the resultant information in a Customer Needs Statement.
Establish initial cost and schedule baselines.
Tell what Mission Analysis does for the customer: 
Mention that this may have been done already, if the customer is already operating with an SE approach.
Discuss ERICAAs:
Expectations
Requirements
Issues
Constraints
Assumptions
Assertions
Mission Profile and System Effectiveness
Landing
Loiter
Descent
Cruise
Climb
Takeoff
Landing
Landing Abort
Capability (Performance):
Takeoff Distance
Climb Rate
Cruise Speed
Descent Rate
Landing Distance
Availability:
Reliability (MTBF)
Maintainability (MTTR)
Logistics Support 
(Spares, Transportation,
Levels of Maintenance)
Dependability:
Reliability (MTBF)
Maintainability (MTTR)
In Flight Shutdowns
Ps = Pd*Ph*Pk (Survivabilty)
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Requirements Analysis
Objectives:
Define system customers
Determine requirements from “desirements”
Validate system requirements with system customers
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Identify system customers and stakeholders.
Expand expectations, requirements, issues, constraints, assumptions and assertions to include input from all customer and stakeholder groups.
Ground assumptions, research issues, confirm constraints, clarify expectations, verify assertions, and detail requirements to the greatest possible extent.
Organize customer and stakeholder input into relevant categories.
Build specific system performance and functional requirements from organized input.
Add requirements from the “-ilities” and verification plans.
Identify known and assumed constraints and add to requirements set.
Establish measurable parameters for all requirements.
Document and control this information in a System Requirements Document (SRD).
Conduct a Systems Requirements Review (SRR) and update the SRD.
Declare all plans and requirements documents as Technical Baseline Revision Level 0.
Develop the derived requirements that govern implementation and document them in system specifications.
Mention the varied membership of the Requirements Analysis Team
Discuss the need to revisit or revise as more is learned
Define “requirement” in the general sense, particularly the idea of “measurability”
 Opposed to ERICAA
Importance of Requirements Analysis
Challenged projects : projects that did not materialize or were not completed on time
37% of the problems with such projects were related to requirements:
13% - poor user input
12% - incomplete requirements
12% - changing requirements
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Types of Requirements
FURPS+
Functional - features, capabilities, security
Usability - human factors, help, documentation
Reliability - frequency of failure, recoverability, predictability
Performance - response times, throughput, accuracy, availability, resource usage
Supportability - adaptability, maintainability, configurability
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The + in FURPS+
Implementation - resource limitations, language and tools, hardware, etc.
Interface - constraints imposed by interfacing with external systems
Operations - system management in its operational setting
Packaging
Legal - licensing and so forth
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Functional Analysis and
Decomposition
Through Functional Architectures and Use of Functional Flow Block Diagrams
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Functional Analysis - Basics
To develop concepts and alternatives that are not technology or component bounded - to avoid “point” solutions
Model possible overall system behaviors (needed to achieve the system requirements)
Decompose functional requirements into discrete tasks or activities (but stay focused on behaviors not technology)
Do this hierarchically BUT iteratively, maintaining traceability (back to requirements)
Top-Down approach with some bottom up checking
Allocate functions to components in system architecture
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Functional Analysis
 (New Product Development)
Definition
Functional analysis is the technique of identifying and describing all the functions of a system
Objectives
To identify or update the functional requirements
To ensure the functions are partitioned in an appropriate manner
To allow the traceability of the functions
To identify the interfaces between functions
Inputs
Functional and performance requirements, constraints, context, external interfaces
Activity
Define system, define level of detail, identify functions, prepare functional hierarchy (tree), prepare functional matrix, prepare functional flow block diagram
Outputs
Context diagram, spec of level of detail, functional hierarchy diagram, functional matrix (N2 diagram), functional flow block diagram
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Perform Air Transport Mission Function Functional Flow
Provide Guidance and Navigation
Provide Communications
Provide Environmental Control
Provide Cargo Capability
Provide Passenger and Crew Accommodations
Provide Thrust
Provide Aerodynamic Performance
Maintain Structural Integrity
Provide Power
Provide Situational Awareness
Provide …….
Perform Pre-flight Operations
Perform Take-off Preparations
Perform Flight Operations
Perform Post-landing Operations
Source: Adapted f rom Jackson, S. Systems Engineering for Commercial Aircraft
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Functional Analysis and Allocation
(Systems Engineering Fundamentals)
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Functional Architecture
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Functional Flow Allocation
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Functional Flow Block Diagram (FFBD)
Purpose: To describe system requirements in functional terms
Structured to ensure that:
All life cycle functions are covered
All elements of system are identified and defined 
(e.g., prime equipment, training, spare parts, data, software, etc.)
System support requirements are identified to specific system functions
Proper sequencing of activities and design relationships are established including critical design interfaces
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Functional Flow Block Diagram Example
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FFBD Characteristics
Functionally oriented—NOT solution oriented
The process of defining lower-level functions and sequencing relationships is often referred to as functional decomposition
Allows traceability vertically through the levels 
A key step in developing the functional architecture from which designs may be synthesized
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Key FFBD Attributes
Function block: Each function on an FFBD should be separate and be represented by single box (solid line). 
Each function needs to stand for definite, finite, discrete action to be accomplished by system elements.
Function numbering: Each level should have a consistent number scheme and provide information concerning function origin. 
(e.g., top level— 1.0, 2.0, 3.0, etc; first indenture (level 2)—1.1, 1.2, 1.3, etc; second indenture (level 3)—1.1.1, 1.1.2, 1.1.3, etc.) 
These numbers establish identification and relationships that will carry through all Functional Analysis and Allocation activities and facilitate traceability from lower to top levels.
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Key FFBD Attributes (cont.)
Functional reference: Each diagram should contain a reference to other functional diagrams by using a functional reference (box in brackets).
Flow connection: Lines connecting functions should only indicate function flow and not a lapse in time or intermediate activity.
Flow direction: Diagrams should be laid out so that the flow direction is generally from left to right. Arrows are often used to indicate functional flows.
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Key FFBD Attributes (cont.)
Summing gates: A circle is used to denote a summing gate and is used when AND/OR is present. 
AND is used to indicate parallel functions and all conditions must be satisfied to proceed. 
OR is used to indicate that alternative paths can be satisfied to proceed.
GO and NO-GO paths: “G” and “_ G” are used to denote “go” and “no-go” conditions. 
These symbols are placed adjacent to lines leaving a particular function to indicate alternative paths.
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FFBD Format
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Introduction to Quality Function Deployment (House of Quality)
Overview of Quality Function Deployment (QFD) diagram to facilitate the translation of customer requirements into engineering characteristics (functional requirements)
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The Flow Of The 
7 M & P Tools 
Into a QFD matrix
Flow of Seven M&P Tools into QFD
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 What is Quality Function Deployment?
QFD is a formal method for capturing the user’s requirements and mapping them onto product and process attributes.
The method relies on constructing a series of complementary matrices describing the association between the Voice-Of-The-Customer, the product features, manufacturing processes, and support characteristics.
The objective of QFD is to separate the important parameters based upon the customer’s desires and to understand the effect of product design on downstream processes.
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Quality = Customer
The foundation of Quality Function Deployment comes from the definition of quality as meeting the customer’s needs with a minimum loss to society. 
There are several voices to The Customer, including the warfighter (user), the taxpayer (buyer), the contractor (builder), the acquisition expert (manager), and many others. 
Ranking these needs is a team effort, and will result in every team member defining the need. Thus, QFD is process for communication and organization within IPTs.
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Quality Function Deployment Terms
Quality Function Deployment (QFD) can be a set of one or more matrices. Each matrix has problem issues, “Whats”, and solution issues, “Hows”.	
The matrix elements relates the ranked set of “Whats” to a set of potential “Hows”, summing up these relationships at the bottom to show the relative importance of each “How”.
The “Hows” of one matrix then are Deployed as the “Whats” of the next matrix with subsequent “Hows”.	
Other properties of problem or solution issues are displayed within “rooms” of the matrix, such as Correlation Matrix, Target Values, and Competitive Assessment
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The Purpose Of QFD
The purpose of QFD is to Define the Problem by identifying the most important product and process characteristics for decision support purposes. (Risk, Metrics, Analysis, Etc.)		
This importance can be judged by a numerical score, by graphical notations, or by correlation with other issues.		
The result of a QFD is NOT the chart, but the interpretation of the chart by team members. The matrix is the means, not the end, and needs to be judged.					
A QFD study should be updated throughout the development process, and is not a static document, 
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The Elements of the Matrix
The “Whats” are the left vertical listing for what is desired to be accomplished. In the first matrix, these are the customer requirements.			
The “Hows” are the top horizontal listing of how to achieve or measure the ”Whats”.			
The Importance is an absolute or relative ranking of the lowest level of the “Whats”. Scales can be low-medium-high, or from 1-10. This importance is multiplied by the level of relationship.			
The Relationship Matrix is a weak-medium-strong level of relationship between a “What” and a“How”.
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The Elements of the Matrix, Continued
The Correlation Matrix, often called the “roof” on the house of quality, is a measure of the interrelationship between different “Hows”, and can show required tradeoffs. These measures are not reflected in numerical rankings.			
The Absolute and Relative Importance at the bottom of the matrix is a summation of the level of relationship of each “What” multiplied by it’s corresponding importance						
Other rooms are competitive assessments, target values, direction of improvement, and risk or difficulty.
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The Elements Of A 
Quality Function Deployment 
Matrix
Key Elements of the QFD Constitute the Rooms of the House of Quality
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Scales and Symbols Used In QFD
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Quality Function Deployment (QFD)
A systematic approach of translating a societal need or a military threat to program specific goals is performed with the QFD technique (Sanchez [1993])
Consists of techniques for creating and completing a series of matrices showing the association between specific features of a product and statements representing the customer requirements
Uses teamwork and creative brainstorming as well as market research to identify customer demands and design parameters
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How to Construct a Matrix.
Decompose “Whats”, and calculate importance. (Affinity, Prioritization)
Decompose “Hows”. (Tree or Affinity).
Find Target Values for “Hows”.
Fill out Relationship Matrix, can use NGT.
Calculate Relative Importance.
Determine Direction of Improvement.
Fill out Correlation Matrix. (Interrelationship)
Conduct Competitive Assessment for Benchmarking.
Rank Risk or Difficulty, relative to target values.
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House of Quality
1 - Customer Requirements
2 - Engineering Characteristics
3 - Relationship Matrix
4 - Correlation Matrix
5 - Importance Rating 
6 - Absolute Importance
7 - Relative Importance
8 - Competitive Assessment
9 - Tech. Competitive Assessment
10 - Technical Difficulty
11 - Target Values
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House of Quality “Rooms” 
Customer Requirements
Frequently referred to as the whats of the House of Quality
Fall into three categories
Spoken requirements
directly indicated by the customer
Unspoken requirements or "hidden" requirements
customer'simplicit needs
Exciters 
"softer" customer requirements that can be traded off against other needs ("bells and whistles”)
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House of Quality “Rooms” 
Engineering Characteristics
Frequently referred to as the hows of the House of Quality
Translation of customer needs into product or process attributes
Identify how the customer requirements can be satisfied
"What can we control that allows us to meet our customer's needs?"
“Must not be specific design details or solutions but must be characteristics that can be measured and given target values” [Dieter (2000)]
Label each how with an indication of the desired direction of improvement
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Body of the House of Quality diagram
Identifies the correlation between the hows and the whats
weak, medium, or strong
then assigned an associated quantitative value
An empty column in the Relationship Matrix indicates that an engineering characteristic previously thought significant does not have an impact on any of the customer requirements
An empty row shows that a customer requirement is not being properly addressed with the current set of engineering characteristics 
The goal of this matrix is not to identify a relationship between each and every how and what but rather to recognize the most important associations
House of Quality “Rooms” 
Relationship Matrix
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Identify the relationships that exist among either the customer requirements or engineering characteristics
Four different relationships 
positive, strong positive, negative, and strong negative
Analysis of this matrix is vital in establishing what trade-offs need to be made
The need for a trade-off is demonstrated by a strong negative relationship in the Correlation Matrix
This is important so that possible trades can be recognized early in the design process when the cost incurred is low and changes in the design are easily made
House of Quality “Rooms” 
Correlation Matrix
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Importance Rating 
Shows the importance of each customer requirement
Ratings are established by taking the results from the requirements definition phase and allocating them along a given scale
Absolute Importance 
Obtained by multiplying the quantitative value in each of the cells of the Relationship Matrix by the respective importance rating
The resulting values are then summed for each column in the Relationship Matrix to produce the absolute importance
Relative Importance 
Absolute importance on a normalized scale from 1 to 100
Facilitates the quick identification of the most significant engineering characteristics for the design problem
House of Quality “Rooms” 
Importances
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Customer Assessment 
Shows how the top few competitive products rank with respect to the customer requirements
Technical Assessment 
Benchmarks the company performance against the same few competitor products for each of the engineering characteristics
Allows the decision-maker to discern the best places to allocate resources in order to out-perform the competition 
House of Quality “Rooms” 
Assessment
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Technical Difficulty 
Shows the ease with which each engineering characteristic can be achieved using a numerical scale
The assigned values are based on estimates by the IPT for the probability of achieving the target values
Target Values 
Contains goals set for each engineering characteristic
The design should be evaluated with respect to these targets throughout the design process
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House of Quality “Rooms” 
Technical Difficulty & Target Values
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Interpreting A QFD Matrix
The Matrix itself is not the final result of the study, but is a means to draw conclusions about the present knowledge.
A simple method of showing importance is a bar chart of the calculated importance of each “How”. This can show division levels.
Scan the relationship matrix for any blank rows or columns, which will show a gap in meeting the customer requirements.
Find strong negative relationships in the correlation matrix, this highlights tradeoffs.
Look for crossings on the competitive assessment, these show poor benchmarks.
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Matrix
Matrix
Matrix
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IPPD Problem Decomposition Through QFD
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House of Quality Summary
The House of Quality is not static
It should be continuously updated and referred to throughout the design process as more knowledge about the problem is obtained
It serves as a reference point to ensure the customer requirements are being properly addressed throughout the design process
Particularly, the Customer and Technical Assessments and the Target Values should be reevaluated as the design progresses 
Deployment of the House of Quality increases in complexity and detail
Top level House of Quality is very broad
Bottom level House of Quality is very specific
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Summary and Conclusions
Requirements and Functional Analyses are essential in taking the needs, e.g. customer requirements; and converting them into functional requirements that can be used to idea key product and process characteristics, i.e. the key engineering characteristics
Quality Function Deployment (QFD) is a key, visual quality engineering method for translating and relating the “voice of the customer” to the necessary key engineering characteristics
The results of the QFD matrix establish the criteria in the Overall Evaluation Criterion (OEC)
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