Requirements Analysis

Lecture 3

Requirements DefinitionRequirements AnalysisRequirements DefinitionRequirements Analysis

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Need Product Requirements Where to start:

What is the product function? What is the state of the product? What are the relevant costs? What is the customer buying experience? What is the field (service, sales, distribution) experience?

Which product characteristics are likely to impactcustomer needs?

Where to start: What is the product function? What is the state of the product? What are the relevant costs? What is the customer buying experience? What is the field (service, sales, distribution) experience?

Which product characteristics are likely to impactcustomer needs?

Benchmarking Critical product analysis

How does it work? How is it made, cost etc? How does it compare with competitors?

Value engineering and Analysis Patents, publications, customer reviews, editorials, trade

show, ads for jobs, build a trend Always consider a higher functional level (changes the game!) Cost Analysis (later topic)

Critical product analysis How does it work? How is it made, cost etc? How does it compare with competitors?

Value engineering and Analysis Patents, publications, customer reviews, editorials, trade

show, ads for jobs, build a trend Always consider a higher functional level (changes the game!) Cost Analysis (later topic)

Exploration Methods Advantages andDisadvantages

Lead Users Lead User methodology was originally developed by Dr. Eric von

Hippel of the MIT and first described in the July 1986 issueof Management Science.

His definition for lead user is; Lead users face needs that will be general in a marketplace but face

them months or years before the bulk of that marketplace encountersthem, and

Lead users are positioned to benefit significantly by obtaining a solution tothose needs.

In other words: Lead users are users of a product or service thatcurrently experience needs still unknown to the public and whoalso benefit greatly if they obtain a solution to these needs.

Because lead users innovate, they are considered to be oneexample or type of the creative consumers phenomenon.

Lead User methodology was originally developed by Dr. Eric vonHippel of the MIT and first described in the July 1986 issueof Management Science.

His definition for lead user is; Lead users face needs that will be general in a marketplace but face

them months or years before the bulk of that marketplace encountersthem, and

Lead users are positioned to benefit significantly by obtaining a solution tothose needs.

In other words: Lead users are users of a product or service thatcurrently experience needs still unknown to the public and whoalso benefit greatly if they obtain a solution to these needs.

Because lead users innovate, they are considered to be oneexample or type of the creative consumers phenomenon.

Lead User Method Introduction The Lead User Method is a market research tool that may be used by

companies and / or individuals seeking to develop breakthroughproducts.

In contrast to the traditional market research techniques that collectinformation from the users at the center of the target market, the LeadUser method takes a different approach, Collecting information about both needs and solutions from the

leading edges of the target market and from analogue markets,markets facing similar problems in a more extreme form.

The methodology involves four major steps: Start of the Lead User process Identification of Needs and Trends Identification of Lead Users and interviews Concept Design (Workshop)

The Lead User Method is a market research tool that may be used bycompanies and / or individuals seeking to develop breakthroughproducts.

In contrast to the traditional market research techniques that collectinformation from the users at the center of the target market, the LeadUser method takes a different approach, Collecting information about both needs and solutions from the

leading edges of the target market and from analogue markets,markets facing similar problems in a more extreme form.

The methodology involves four major steps: Start of the Lead User process Identification of Needs and Trends Identification of Lead Users and interviews Concept Design (Workshop)

Lead User Method Introduction The methodology is based upon the idea that breakthrough products may

be developed by identifying leading trends in the to-be-developedproducts associated marketplace(s). Once the trend or broader problem to be solved has been identified,

the developers seek out Lead Users- people or organizations thatare attempting to solve a particularly extreme or demanding versionof the stated problem.

For example, a company seeking to create a breakthrough in flashlightdesign may seek out policemen, home inspectors, or others who requirebright, efficient lights as part of their day to day business

The methodology is based upon the idea that breakthrough products maybe developed by identifying leading trends in the to-be-developedproducts associated marketplace(s). Once the trend or broader problem to be solved has been identified,

the developers seek out Lead Users- people or organizations thatare attempting to solve a particularly extreme or demanding versionof the stated problem.

For example, a company seeking to create a breakthrough in flashlightdesign may seek out policemen, home inspectors, or others who requirebright, efficient lights as part of their day to day business

RequirementsDefinition and Analysis

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Requirements Explosion More and more

requirements wereadded as systemsgrew in performanceand complexity.Source: AIAA MDOTC White Paper,1991

WHY??

Source: AIAA MDOTC White Paper,1991

Purpose of Requirements Definition Process Establishes the basis for agreement between the stakeholders

and the developers on what the product is to do Reduces the development effort because less rework is

required to address poorly written, missing, andmisunderstood requirements; Forces the relevant stakeholders to consider rigorously all of the

requirements before design begins Careful review can reveal omissions, misunderstandings, and

inconsistencies early in the development cycle Provides a basis forestimating costs and schedules

The description of the product to be developed as given in therequirements is a realistic basis for estimating project costs andcan be used to evaluate bids or price estimates

Establishes the basis for agreement between the stakeholdersand the developers on what the product is to do

Reduces the development effort because less rework isrequired to address poorly written, missing, andmisunderstood requirements; Forces the relevant stakeholders to consider rigorously all of the

requirements before design begins Careful review can reveal omissions, misunderstandings, and

inconsistencies early in the development cycle Provides a basis forestimating costs and schedules

The description of the product to be developed as given in therequirements is a realistic basis for estimating project costs andcan be used to evaluate bids or price estimates

Purpose of Requirements Definition Process

Provides a baseline for verification Organizations can develop their validation and verification plans much

more productively from a good requirements document. The requirements document provides a baseline against which

compliance can be measured. The requirements are also used to provide the stakeholders with a

basis for acceptance of the system. Facilitates transfer of the product to new users or new

machines. Serve as a basis for later enhancement or alteration of the

finished product.

Provides a baseline for verification Organizations can develop their validation and verification plans much

more productively from a good requirements document. The requirements document provides a baseline against which

compliance can be measured. The requirements are also used to provide the stakeholders with a

basis for acceptance of the system. Facilitates transfer of the product to new users or new

machines. Serve as a basis for later enhancement or alteration of the

finished product.

Purpose of Requirements Definition Process The purpose of the Stakeholder Requirements Definition

Process is to define the requirements for a system that canprovide the services needed by users and other stakeholdersin a defined environment.

It identifies stakeholders, or stakeholder classes, involved withthe system throughout its life cycle, and their needs,expectations, and desires.

It analyzes and transforms these into a common set ofstakeholder requirements that express the intendedinteraction the system will have with its operationalenvironment and that are the reference against which eachresulting operational service is validated.

The purpose of the Stakeholder Requirements DefinitionProcess is to define the requirements for a system that canprovide the services needed by users and other stakeholdersin a defined environment.

It identifies stakeholders, or stakeholder classes, involved withthe system throughout its life cycle, and their needs,expectations, and desires.

It analyzes and transforms these into a common set ofstakeholder requirements that express the intendedinteraction the system will have with its operationalenvironment and that are the reference against which eachresulting operational service is validated.

Purpose of Requirements Definition Process Provide early assurance that all top-level requirements are fully

satisfied in the product, with traceability to where they aresatisfied.

Prevent unintentional addition of cost (avoid gold plating). Establish clear responsibility for requirements implementation. Provide clear visibility across teams into requirements

allocation and cross-functional interactions. Easily and quickly assess the impact of changes to

requirements. Provide data for early and thorough validation and verification

of requirements and design artifacts. Avoid unpleasant downstream surprises!

Provide early assurance that all top-level requirements are fullysatisfied in the product, with traceability to where they aresatisfied.

Prevent unintentional addition of cost (avoid gold plating). Establish clear responsibility for requirements implementation. Provide clear visibility across teams into requirements

allocation and cross-functional interactions. Easily and quickly assess the impact of changes to

requirements. Provide data for early and thorough validation and verification

of requirements and design artifacts. Avoid unpleasant downstream surprises!

Goal of Requirements Definition Process

The Technical Requirements DefinitionProcess is used to

transform the baseline stakeholderexpectations into unique, quantitative,and measurable technical requirements

The Technical Requirements DefinitionProcess is used to

transform the baseline stakeholderexpectations into unique, quantitative,and measurable technical requirements

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Types of Requirements Functional Requirements define what functions need to be

done to accomplish the mission objectives Example: The Thrust Vector Controller (TVC) shall provide vehicle

control about the pitch and yaw axes. This statement describes a high level function that the TVC must

perform. Statement has form of Actor Action Verb object acted on

Performance Requirements define how well the systemneeds to perform the functions Example: The TVC shall gimbal the engine a maximum of 9 degrees,

+/- 0.1 degree

Functional Requirements define what functions need to bedone to accomplish the mission objectives Example: The Thrust Vector Controller (TVC) shall provide vehicle

control about the pitch and yaw axes. This statement describes a high level function that the TVC must

perform. Statement has form of Actor Action Verb object acted on

Performance Requirements define how well the systemneeds to perform the functions Example: The TVC shall gimbal the engine a maximum of 9 degrees,

+/- 0.1 degree

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Types of Requirements Constraints are requirements that cannot be traded off with

respect to cost, schedule or performance Example: The TVC shall weigh less than 120 lbs.

Interface Requirements Example: The TVC shall interface with the J-2X per conditions

specified in the CxP 72262 Ares I US J-2X Interface Control Document,Section 3.4.3.

Environmental requirements Example: The TVC shall use the vibro-acoustic and shock [loads]

defined in CxP 72169, Ares 1 Systems Vibro-acoustic and ShockEnvironments Data Book in all design, analysis and testing activities.

Other requirement types described in the SE Handbookinclude: human factors, reliability requirements, and safetyrequirements.

Constraints are requirements that cannot be traded off withrespect to cost, schedule or performance Example: The TVC shall weigh less than 120 lbs.

Interface Requirements Example: The TVC shall interface with the J-2X per conditions

specified in the CxP 72262 Ares I US J-2X Interface Control Document,Section 3.4.3.

Environmental requirements Example: The TVC shall use the vibro-acoustic and shock [loads]

defined in CxP 72169, Ares 1 Systems Vibro-acoustic and ShockEnvironments Data Book in all design, analysis and testing activities.

Other requirement types described in the SE Handbookinclude: human factors, reliability requirements, and safetyrequirements.

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Requirements Standards NASA Systems Engineering Handbook

NASA/SP-2007-6105 Section 4.2 (pp. 40-48) Technical Requirements Definition Section 6.2 (pp. 131-135) Requirements Management Appendix C (pp. 279-281) How to write a good Requirement Appendix D (pp. 282-283) Requirements Verification Matrix

International Council of Systems Engineering (INCOSE) Systems Engineering Handbook, Version 3.1

Requirements Working Group http://www.incose.org/practice/techactivities/wg/rqmts/ ISO/IEC 15288 (IEEE STD 15288-2008) Systems and Software Engineering System Life Cycle Processes Stakeholder Requirements Definition Process

NASA Systems Engineering Handbook NASA/SP-2007-6105

Section 4.2 (pp. 40-48) Technical Requirements Definition Section 6.2 (pp. 131-135) Requirements Management Appendix C (pp. 279-281) How to write a good Requirement Appendix D (pp. 282-283) Requirements Verification Matrix

International Council of Systems Engineering (INCOSE) Systems Engineering Handbook, Version 3.1

Requirements Working Group http://www.incose.org/practice/techactivities/wg/rqmts/ ISO/IEC 15288 (IEEE STD 15288-2008) Systems and Software Engineering System Life Cycle Processes Stakeholder Requirements Definition Process

Voice of the customerorigins of the DC-3

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Wright BrothersSignal Corps Contract - 1908

The first formal Army airplane contractbetween the U.S. Army Signal Corps andthe Wright Brothers, signed February10, 1908.

The Wright Brothers originally offeredtheir flying machine for sale to the U.S.War Department in January of 1905,but three years passed before thefederal government developed seriousinterest.

In the first formal Army airplanecontract signed by the Wrights and theU. S. Signal Corps, the brothers promiseto deliver, in two hundred days, aheavier-than-air flying machine thatmeets the Corps' Specification No. 486.

The Wright Brothers received $25,000

The first formal Army airplane contractbetween the U.S. Army Signal Corps andthe Wright Brothers, signed February10, 1908.

The Wright Brothers originally offeredtheir flying machine for sale to the U.S.War Department in January of 1905,but three years passed before thefederal government developed seriousinterest.

In the first formal Army airplanecontract signed by the Wrights and theU. S. Signal Corps, the brothers promiseto deliver, in two hundred days, aheavier-than-air flying machine thatmeets the Corps' Specification No. 486.

The Wright Brothers received $25,0009/15/2013 19

It is desirable that the flying machine should be designed sothat it may be quickly and easily assembled and taken apart andpacked for transportation in army wagons. It should be capableof being assembled and put in operating condition in about onehour. The flying machine must be designed to carry two personshaving a combined weight of about 350 pounds, also sufficientfuel for a flight of 125 miles. The flying machine should be designed to have a speed of atleast forty miles per hour still air, but bidders must submitquotations in their proposals for cost depending upon thespeed attained during the trial flight, according to the followingscale:

40 miles per hour, 100 per cent.39 miles per hour, 90 per cent.38 miles per hour, 80 per cent.37 miles per hour, 70 per cent.36 miles per hour, 60 per cent.Less than 36 miles per hour rejected.41 miles per hour, 110 per cent.42 miles per hour, 120 per cent.43 miles per hour, 130 per cent.44 miles per hour, 140 per cent.

Wright BrothersSignal Corps Contract - 1908

It is desirable that the flying machine should be designed sothat it may be quickly and easily assembled and taken apart andpacked for transportation in army wagons. It should be capableof being assembled and put in operating condition in about onehour. The flying machine must be designed to carry two personshaving a combined weight of about 350 pounds, also sufficientfuel for a flight of 125 miles. The flying machine should be designed to have a speed of atleast forty miles per hour still air, but bidders must submitquotations in their proposals for cost depending upon thespeed attained during the trial flight, according to the followingscale:

40 miles per hour, 100 per cent.39 miles per hour, 90 per cent.38 miles per hour, 80 per cent.37 miles per hour, 70 per cent.36 miles per hour, 60 per cent.Less than 36 miles per hour rejected.41 miles per hour, 110 per cent.42 miles per hour, 120 per cent.43 miles per hour, 130 per cent.44 miles per hour, 140 per cent.9/15/2013 20

The speed accomplished during the trial flight will bedetermined by taking an average of the time over ameasured course of more than five miles, against and withwind. The time will be taken by a flying start, passing thestarting point at full speed at both ends of the course. Thistest subject to such additional details as the Chief SignalOfficer of the Army may prescribe at the time. Before acceptance a trial endurance flight will be requiredof at least one hour during which time the flying machinemust remain continuously in the air without landing. ITshall return to the starting point and land without anydamage that would prevent it immediately starting uponanother flight. During this trial flight of one hour it must besteered in all directions without difficulty and at all timesunder perfect control and equilibrium. Three trials will be allowed for sped as provided for inparagraphs 4 and 5. Three trials for endurance as providedfor in paragraph 6, and both tests must be completedwithin a period of thirty days from the date of delivery. Theexpense of the tests to be borne by the manufacturer. Theplace of delivery to the Government and trial flights will beat Fort Myer, Virginia.

Wright BrothersSignal Corps Contract - 1908

The speed accomplished during the trial flight will bedetermined by taking an average of the time over ameasured course of more than five miles, against and withwind. The time will be taken by a flying start, passing thestarting point at full speed at both ends of the course. Thistest subject to such additional details as the Chief SignalOfficer of the Army may prescribe at the time. Before acceptance a trial endurance flight will be requiredof at least one hour during which time the flying machinemust remain continuously in the air without landing. ITshall return to the starting point and land without anydamage that would prevent it immediately starting uponanother flight. During this trial flight of one hour it must besteered in all directions without difficulty and at all timesunder perfect control and equilibrium. Three trials will be allowed for sped as provided for inparagraphs 4 and 5. Three trials for endurance as providedfor in paragraph 6, and both tests must be completedwithin a period of thirty days from the date of delivery. Theexpense of the tests to be borne by the manufacturer. Theplace of delivery to the Government and trial flights will beat Fort Myer, Virginia.

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It should be so designed as to ascend in any countrywhich may be encountered in field service. Thestarting device must be simple and transportable. Itshould also land in a field without requiring aspecially prepared spot and without damaging itsstructure. It should be provided with some device to permit ofa safe descent in case of an accident to thepropelling machinery. It should be sufficiently simple in its constructionand operation to permit an intelligent man tobecome proficient in its use within a reasonablelength of time.

Wright BrothersSignal Corps Contract - 1908

It should be so designed as to ascend in any countrywhich may be encountered in field service. Thestarting device must be simple and transportable. Itshould also land in a field without requiring aspecially prepared spot and without damaging itsstructure. It should be provided with some device to permit ofa safe descent in case of an accident to thepropelling machinery. It should be sufficiently simple in its constructionand operation to permit an intelligent man tobecome proficient in its use within a reasonablelength of time.

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User Generated RequestModular, Fractionated Space System Advanced Concept Technology

Demonstrator

Technology advances such as component miniaturization, aswell as innovative approaches, make it likely that spacesystem weight and volume can be reduced in the next decade,resulting in reduced cost. However, true cost reductions,coupled with new requirements for time reductions fromconcept to launch to operations make it unlikely thatminiaturization will be able to reduce time and cost for somecritical needs. New design concepts such as deployableactively controlled membranes, connected and unconnectedsparse aperture mirrors, and modularized space systemconcepts launched on small rockets are among the many newconcepts being proposed for future systems. In addition,virtual links between space system modules, enabled bywireless systems and adaptive control algorithms, will reducestructural component weight and blur the distinction betweenpayload and the vehicle bus.

Technology advances such as component miniaturization, aswell as innovative approaches, make it likely that spacesystem weight and volume can be reduced in the next decade,resulting in reduced cost. However, true cost reductions,coupled with new requirements for time reductions fromconcept to launch to operations make it unlikely thatminiaturization will be able to reduce time and cost for somecritical needs. New design concepts such as deployableactively controlled membranes, connected and unconnectedsparse aperture mirrors, and modularized space systemconcepts launched on small rockets are among the many newconcepts being proposed for future systems. In addition,virtual links between space system modules, enabled bywireless systems and adaptive control algorithms, will reducestructural component weight and blur the distinction betweenpayload and the vehicle bus.

Space System List

Reduced cost of large systems Increased reliability Reduced weight Reduced volume

Reduced cost of large systems Increased reliability Reduced weight Reduced volume

More User Info

Compared to terrestrial systems, space systems are very costly andhave several disadvantages compared to terrestrial systems. First ofall, the cost of delivery to orbit is a significant part of the systemcost. The consequences of a single launch vehicle failure areenormous since the entire system will be lost, leading to long delaysin the deployment of vital satellites. The life of successful systems isshort due to demands for propellant to conduct station-keeping andnavigation and control. Critical system components are oftendesigned to be redundant, adding to weight and cost.

This Design Opportunity is looking for innovative concepts for theprototype of a new, space-based Earth orbiting system to replacemonolithic satellites. This new system, like a PC computer system, isto be versatile and modular so that it can be more reliable, moreresponsive, upgradeable and capable of being launched in componentform so that risk of a single failure is removed. It should anticipatethe need for large area terrestrial surveillance by having thecapability of operating in different orbital planes without the need forlarge quantities of onboard propellant.

Prime areas to consider are the area monitored and the resolution both in a wideangle and narrow field of view. It is important to understand how these choicesinfluence orbit selection, system weight and complexity.

Compared to terrestrial systems, space systems are very costly andhave several disadvantages compared to terrestrial systems. First ofall, the cost of delivery to orbit is a significant part of the systemcost. The consequences of a single launch vehicle failure areenormous since the entire system will be lost, leading to long delaysin the deployment of vital satellites. The life of successful systems isshort due to demands for propellant to conduct station-keeping andnavigation and control. Critical system components are oftendesigned to be redundant, adding to weight and cost.

This Design Opportunity is looking for innovative concepts for theprototype of a new, space-based Earth orbiting system to replacemonolithic satellites. This new system, like a PC computer system, isto be versatile and modular so that it can be more reliable, moreresponsive, upgradeable and capable of being launched in componentform so that risk of a single failure is removed. It should anticipatethe need for large area terrestrial surveillance by having thecapability of operating in different orbital planes without the need forlarge quantities of onboard propellant.

Prime areas to consider are the area monitored and the resolution both in a wideangle and narrow field of view. It is important to understand how these choicesinfluence orbit selection, system weight and complexity.

Space System List

Reduced cost of large systems Increased reliability Reduced weight Reduced volume Increase system life System must be replenishable System must be upgradeable System should minimize redundancy System should demonstrate modular

design System must be modular Capable of being launched in modular

form Capable of being assembled in orbit

Must operate in wide range oforbital planes for wide areacoverage

Monitor critical areas of the Earth Achieve high resolution Be responsive to requests for data Reduce need for system onboard

propellant storage

Reduced cost of large systems Increased reliability Reduced weight Reduced volume Increase system life System must be replenishable System must be upgradeable System should minimize redundancy System should demonstrate modular

design System must be modular Capable of being launched in modular

form Capable of being assembled in orbit

Must operate in wide range oforbital planes for wide areacoverage

Monitor critical areas of the Earth Achieve high resolution Be responsive to requests for data Reduce need for system onboard

propellant storage

Plus more

Proposals are solicited for advanced concepts with the following features. Thesystem is to have the far field imaging capability of the Hubble Space Telescope(JWST), but have additional capabilities. While Hubble and JWST look onlyoutward (JWST is not in LEO, but at L2, far away from Earth, where we wantour system to operate), this system must also look down at the Earth. How thesystem looks down, whether the additional system is attached to the main vehicle,the field of view and resolution are left to the bidder.

The space system will have the capability of being launched in small vehicles,the vehicle type and number to be provided by the bidder, with special attentionbeing paid to the system cost, responsiveness, assembly difficulty, ground check-out time and cost and the consequences of a failure of any one vehicle.

The onboard processing units must be upgradeable and expandable at areasonable cost. This capability will provide the system with the ability tochange its mission by simply adding new modular features. The system mustalso be refuelable to extend the life of the satellite in low Earth orbit and toprovide modest orbital parameter changes or fuel for assembly, as required.

Proposals are solicited for advanced concepts with the following features. Thesystem is to have the far field imaging capability of the Hubble Space Telescope(JWST), but have additional capabilities. While Hubble and JWST look onlyoutward (JWST is not in LEO, but at L2, far away from Earth, where we wantour system to operate), this system must also look down at the Earth. How thesystem looks down, whether the additional system is attached to the main vehicle,the field of view and resolution are left to the bidder.

The space system will have the capability of being launched in small vehicles,the vehicle type and number to be provided by the bidder, with special attentionbeing paid to the system cost, responsiveness, assembly difficulty, ground check-out time and cost and the consequences of a failure of any one vehicle.

The onboard processing units must be upgradeable and expandable at areasonable cost. This capability will provide the system with the ability tochange its mission by simply adding new modular features. The system mustalso be refuelable to extend the life of the satellite in low Earth orbit and toprovide modest orbital parameter changes or fuel for assembly, as required.

Space System List

Reduced cost of large systems Increased reliability Reduced weight Reduced volume Increase system life System must be replenishable System must be upgradeable System should minimize redundancy System should demonstrate modular design System must be modular Capable of being launched in modular form Capable of being assembled in orbit Capable of being launched on small vehicles Reduce consequences of launch failure

Must operate in wide range oforbital planes for wide area coverage Monitor critical areas of the Earth Achieve high resolution Be responsive to requests for data Reduce need for system onboardpropellant storage Space pictures must be as good asHubble Earth pictures must be as good asSPOT Onboard computer processing mustbe upgradeable Data must go to West Lafayette Must be able to add new missions Must be available as a test bed fornew technologies

Reduced cost of large systems Increased reliability Reduced weight Reduced volume Increase system life System must be replenishable System must be upgradeable System should minimize redundancy System should demonstrate modular design System must be modular Capable of being launched in modular form Capable of being assembled in orbit Capable of being launched on small vehicles Reduce consequences of launch failure

Must operate in wide range oforbital planes for wide area coverage Monitor critical areas of the Earth Achieve high resolution Be responsive to requests for data Reduce need for system onboardpropellant storage Space pictures must be as good asHubble Earth pictures must be as good asSPOT Onboard computer processing mustbe upgradeable Data must go to West Lafayette Must be able to add new missions Must be available as a test bed fornew technologies

and, finally

This system will have added complexity as a cost of versatility; however, thesystem must clearly show serious attempts to minimize complexity by simplifyingor eliminating linkages and components.

Ground communication will be centralized in West Lafayette, Indiana. Thebidder will clearly show how the system is down-linked to West Lafayette and thenumber and location of intermediate telemetry. Communications and data rateswill be determined by the bidder.

Initial operation will occur in 2011, but a description of anticipatedimprovements to the system, based upon bidder knowledge of state-of-the-artdevelopment likely to occur, must be presented in the proposal. In addition, thebidder will present at least two additional Concepts of Operation, military orcommercial, that can be supported by their design by the year 2021.

This system will have added complexity as a cost of versatility; however, thesystem must clearly show serious attempts to minimize complexity by simplifyingor eliminating linkages and components.

Ground communication will be centralized in West Lafayette, Indiana. Thebidder will clearly show how the system is down-linked to West Lafayette and thenumber and location of intermediate telemetry. Communications and data rateswill be determined by the bidder.

Initial operation will occur in 2011, but a description of anticipatedimprovements to the system, based upon bidder knowledge of state-of-the-artdevelopment likely to occur, must be presented in the proposal. In addition, thebidder will present at least two additional Concepts of Operation, military orcommercial, that can be supported by their design by the year 2021.

My Space System Objectives List

Reduced cost of large systems Increased reliability Reduced weight Reduced volume Increase system life System must be replenishable System must be upgradeable System should minimize redundancy System should demonstrate modular design System must be modular Capable of being launched in modular form Capable of being assembled in orbit Capable of being launched on small vehicles Reduce consequences of launch failure Reduce complexity Simplify components Demonstrate innovation and integration of new

technology Create new design paradigm

Must operate in wide range of orbitalplanes for wide area coverage Monitor critical areas of the Earth Achieve high resolution Be responsive to requests for data Reduce need for system onboardpropellant storage Space pictures must be as good asHubble Earth pictures must be as good as SPOT Onboard computer processing must beupgradeable Data must go to West Lafayette Must be able to add new missions Show two alternative missions Must be available as a test bed for newtechnologies Initial operation by 2011

Reduced cost of large systems Increased reliability Reduced weight Reduced volume Increase system life System must be replenishable System must be upgradeable System should minimize redundancy System should demonstrate modular design System must be modular Capable of being launched in modular form Capable of being assembled in orbit Capable of being launched on small vehicles Reduce consequences of launch failure Reduce complexity Simplify components Demonstrate innovation and integration of new

technology Create new design paradigm

Must operate in wide range of orbitalplanes for wide area coverage Monitor critical areas of the Earth Achieve high resolution Be responsive to requests for data Reduce need for system onboardpropellant storage Space pictures must be as good asHubble Earth pictures must be as good as SPOT Onboard computer processing must beupgradeable Data must go to West Lafayette Must be able to add new missions Show two alternative missions Must be available as a test bed for newtechnologies Initial operation by 2011

What are Requirements for Automobile ?

Dishwasher?

Copy machine ?

Helicopter ?

Requirements use shall The system shall provide The system shall be capable of The system shall weigh

Automobile ?

Dishwasher?

Copy machine ?

Helicopter ?9/15/2013 31

HOW??

Requirements Definition? Requirements describe the necessary functions and features

of the system we are to conceive, design, implement andoperate Performance Schedule Other Characteristics (e.g. lifecycle properties)

Requirements are often organized hierarchically At a high level requirements focus on what should be

achieved and not how to achieve it Requirements are specified at every level, from the overall

system to each hardware and software component Critically important to establish properly Direct Impact on the Cost

Requirements describe the necessary functions and featuresof the system we are to conceive, design, implement andoperate Performance Schedule Other Characteristics (e.g. lifecycle properties)

Requirements are often organized hierarchically At a high level requirements focus on what should be

achieved and not how to achieve it Requirements are specified at every level, from the overall

system to each hardware and software component Critically important to establish properly Direct Impact on the Cost9/15/2013 33

Attributes of Acceptable Requirements A complete sentence with a single shall per numbered statement Clear and consistent readily understandable Correct does not contain error of fact Feasible can be satisfied within natural physical constraints, state of the art

technologies, and other project constraints Flexibility Not stated as to how it is to be satisfied Without ambiguity only one interpretation Singular One actor-verb-object requirement Verify can be proved at the level of the architecture applicable

Characteristics for pairs and sets of Requirement Statements: Absence of redundancy each requirement specified only once Consistency terms used consistent Completeness usable to form a set of design-to requirements Absence of Conflicts not in conflict with other requirements or itself

A complete sentence with a single shall per numbered statement Clear and consistent readily understandable Correct does not contain error of fact Feasible can be satisfied within natural physical constraints, state of the art

technologies, and other project constraints Flexibility Not stated as to how it is to be satisfied Without ambiguity only one interpretation Singular One actor-verb-object requirement Verify can be proved at the level of the architecture applicable

Characteristics for pairs and sets of Requirement Statements: Absence of redundancy each requirement specified only once Consistency terms used consistent Completeness usable to form a set of design-to requirements Absence of Conflicts not in conflict with other requirements or itself

9/15/2013 34

Attributes of Acceptable Requirements Well stated requirements exhibit the following attributes:

The requirement is Necessary What would happen if you didnt include this requirement?

The requirement is Verifiable How will you know you have met the requirement?

The requirement is Attainable Requirements are concise and unambiguous Good requirements are solution-neutral Requirements are consistent (non-contradictory)

Well stated requirements exhibit the following attributes: The requirement is Necessary

What would happen if you didnt include this requirement? The requirement is Verifiable

How will you know you have met the requirement? The requirement is Attainable

Requirements are concise and unambiguous Good requirements are solution-neutral Requirements are consistent (non-contradictory)

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Requirements Decomposition Requirements are decomposed in a

hierarchical structure starting withthe highest level requirements.

These high-level requirements aredecomposed into functional andperformance requirements andallocated across the system.

These are then further decomposedand allocated among the elementsand subsystems.

Thus, complete set of design-torequirements is achieved.

At each level of decomposition(system, subsystem, component,etc.), the total set of derivedrequirements must be validatedagainst the stakeholder expectationsor higher level parent requirements.

Requirements are decomposed in ahierarchical structure starting withthe highest level requirements.

These high-level requirements aredecomposed into functional andperformance requirements andallocated across the system.

These are then further decomposedand allocated among the elementsand subsystems.

Thus, complete set of design-torequirements is achieved.

At each level of decomposition(system, subsystem, component,etc.), the total set of derivedrequirements must be validatedagainst the stakeholder expectationsor higher level parent requirements.

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Requirements Allocation Decompose system requirements into lower levels ofdesign.

Define all the lower level functions which must beperformed to satisfy the requirement Create architecture of sub-components to provide thosefunctions

Allocate a level of performance to each lower levelfunction Specify interface requirements to other sub-systems

Closure - Ensure that satisfaction of the set ofrequirements at the lower level will guaranteesatisfaction of the higher level requirement.

Decompose system requirements into lower levels ofdesign. Define all the lower level functions which must beperformed to satisfy the requirement Create architecture of sub-components to provide thosefunctions

Allocate a level of performance to each lower levelfunction Specify interface requirements to other sub-systems

Closure - Ensure that satisfaction of the set ofrequirements at the lower level will guaranteesatisfaction of the higher level requirement.

Requirement Allocation Process

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What is the Requirements Definition andAnalysis Process?

INCOSE Systems Engineering Handbookversion 3.2 January 2010

MOE, MOP, TPM Relationship

Example of MOE/MOP/TPMRelationship

The System Engineering Process

Monitoring Requirements

Common Problems Writing implementations (How) instead of requirements

(What) Using incorrect terms

Use shall for requirements Using incorrect sentence structure or bad grammar

Writing implementations (How) instead of requirements(What)

Using incorrect terms Use shall for requirements

Using incorrect sentence structure or bad grammar

Common Problems

Writing unverifiable requirements e.g., minimize, maximize, rapid, user-friendly, easy,sufficient, adequate, quick

Missing requirements Requirement drivers include

Functional, Performance, Interface, Environment, Facility,Transportation, Training, Personnel, Reliability,Maintainability, Operability, Safety

Requirements only written for first use Over-specifying

Writing unverifiable requirements e.g., minimize, maximize, rapid, user-friendly, easy,sufficient, adequate, quick

Missing requirements Requirement drivers include

Functional, Performance, Interface, Environment, Facility,Transportation, Training, Personnel, Reliability,Maintainability, Operability, Safety

Requirements only written for first use Over-specifying

Verification

Every requirement must be verified to ensurethat the proposed design actually satisfies therequirement by Examination, Test, Demonstration, or Analysis

Requirement documentation specifies thedevelopment phase and method of verification

Every requirement must be verified to ensurethat the proposed design actually satisfies therequirement by Examination, Test, Demonstration, or Analysis

Requirement documentation specifies thedevelopment phase and method of verification

Requirements Summary Requirements use shall

The system shall provide The system shall be capable of The system shall weigh

Focus on what needs to be achieved not how Helps to organize teams, tasks and processes Enhances creativity by decomposing problems Function or function sets derived from customer needsdefines subsystems that minimize the number ofinternal interfaces (system engineering) Interface specifications and protocols definition canbegin prior to form design

Requirements use shall The system shall provide The system shall be capable of The system shall weigh

Focus on what needs to be achieved not how Helps to organize teams, tasks and processes Enhances creativity by decomposing problems Function or function sets derived from customer needsdefines subsystems that minimize the number ofinternal interfaces (system engineering) Interface specifications and protocols definition canbegin prior to form design