System-Engineering(ppt文档).ppt

Introduction to System EngineeringSYUCT,Yuan Decheng2012-AutumncontentsFundamentals of Systems EngineeringProgram/Project Life CycleSystem DesignProduct RealizationCrosscutting Technical ManagementTool:Six-sigma black-belts basicCOmputational INfrastructure for Operations Research:http:/www.coin-or.org/Lesson OneFundamentals of Systems Engineering1.What is system engineering2.role and responsibility of the systems engineer3.Example Premise4.Cost Aspect of Systems Engineering1.What is system engineeringSystems engineering is a methodical,disciplined approach for the design,realization,technical management,operations,and retirement of a system.A“system”is a construct or collection of different elements that together produce results not obtainable by the elements alone.(1+12)The elements,or parts,can include people,hardware,software,facilities,policies,and documents.1.What is system engineeringAll things required to produce system-level results.The results include system-level qualities,properties,characteristics,functions,behavior,and performance.The value added by the system as a whole,beyond that contributed independently by the parts,is primarily created by the relationship among the parts.1.What is system engineeringIt is a way of looking at the“big picture”when making technical decisions.It is a way of achieving stakeholder functional,physical,and operational performance requirements in the intended use environment over the planned life of the systems.Systems engineering is a logical way of thinking.1.What is system engineeringSystems engineering is the art and science of developing an operable system capable of meeting requirements within often opposed constraints.Systems engineering is a holistic,integrative discipline,wherein the contributions of structural engineers,electrical engineers,mechanism designers,power engineers,human factors engineers,and many more disciplines are evaluated and balanced,one against another,to produce a coherent whole that is not dominated by the perspective of a single discipline.SE:overall project management1.What is system engineeringSystems engineering seeks a safe and balanced design in the face of opposing interests and multiple,sometimes conflicting constraints.The systems engineer must develop the skill and instinct for identifying and focusing efforts on assessments to optimize the overall design and not favor one system/subsystem at the expense of another.The art is in knowing when and where to probe.Personnel with these skills are usually tagged as“systems engineers.”2.role and responsibility of the systems engineerThe exact role and responsibility of the systems engineer may change from project to project depending on the size and complexity of the project and from phase to phase of the life cycle.For large projects,there may be one or more systems engineers.For small projects,sometimes the project manager may perform these practices.Whoever assumes those responsibilities,the systems engineering functions must be performed.2.role and responsibility of the systems engineerThe lead systems engineer ensures that the system technically fulfills the defined needs and requirements and that a proper systems engineering approach is being followed.The systems engineer oversees the projects systems engineering activities as performed by the technical team and directs,communicates,monitors,and coordinates tasks.The systems engineer reviews and evaluates the technical aspects of the project to ensure that the systems/subsystems engineering processes are functioning properly and evolves the system from concept to product.The entire technical team is involved in the systems engineering process.2.role and responsibility of the systems engineerThe systems engineer will usually play the key role in leading the development of the system architecture,defining and allocating requirements,evaluating design tradeoffs,balancing technical risk between systems,defining and assessing interfaces,providing oversight of verification and validation activities,as well as many other tasks.The systems engineer will usually have the prime responsibility in developing many of the project documents,including the Systems Engineering Management Plan(SEMP),requirements/specification documents,verification and validation documents,certification packages,and other technical documentation.Summarythe systems engineer is skilled in the art and science of balancing organizational and technical interactions in complex systems.However,since the entire team is involved in the systems engineering approach,in some ways everyone is a systems engineer.Systems engineering is about tradeoffs and compromises,about generalists rather than specialists.Systems engineering is about looking at the“big picture”and not only ensuring that they get the design right(meet requirements)but that they get the right design.2.Systems Engineering Processes andRequirementssystem designproduct realizationtechnical management.The systems engineering engine2.1 System Design ProcessesThe four system design are used to define and baseline stakeholder expectations,generate and baseline technical requirements,and convert the technical requirements into a design solution that will satisfy the baselined stakeholder expectations.2.2 Product Realization ProcessesThe product realization processes are applied to each operational/mission product in the system structure starting from the lowest level product and working up to higher level integrated products.These processes are used to create the design solution for each product and to verify,validate,and transition up to the next hierarchical level products that satisfy their design solutions and meet stakeholder expectations as a function of the applicable life-cycle phase2.3 Technical Management ProcessesThe technical management processes are used to establish and evolve technical plans for the project,to manage communication across interfaces,to assess progress against the plans and requirements for the system products or services,to control technical execution of the project through to completion,and to aid in the decision making process.A miniaturized conceptualization of the poster-size NASA project life-cycle process flow for flight and ground systemsPhasePurposeTypical OutputFormulationPre-Phase A Concept StudiesTo produce a broad spectrum of ideas and alternatives for missions from which new programs/projects can be selected.Determine feasibility of desired system,develop mission concepts,draft system-level requirements,identify potential technology needs.Feasible system concepts in the form of simulations,analysis,study reports,models,and mockupsPhase A Concept and TechnologyDevelopmentTo determine the feasibility and desirability of a suggested new major system and establish an initial baseline compatibility with NASAs strategic plans.Develop final mission concept,system-level requirements,and needed system structure technology developments.System concept definition in the form of simulations,analysis,engineering models,and mockups and trade study definitionPhase B Preliminary Design and TechnologyCompletionTo define the project in enough detail to establish an initial baseline capable of meeting mission needs.Develop system structure end product(and enabling product)requirements and generate a preliminary design for each system structure end product.End products in the form of mockups,trade study results,specification and interface documents,and prototypesImplementationPhase C Final Designand FabricationTo complete the detailed design of the system(and its associated subsystems,including its operations systems),fabricate hardware,and code software.Generate final designs for each system structure end product.End product detailed designs,end product component fabrication,and software developmentPhase D SystemAssembly,Integration and Test,LaunchTo assemble and integrate the products to create the system,meanwhile developing confidence that it will be able to meet the system requirements.Launch and prepare for operations.Perform system end product implementation,assembly,integration and test,and transition to use.Operations-ready system end product with supporting related enablingproductsPhase E Operations and SustainmentTo conduct the mission and meet the initially identified need and maintain support for that need.Implement the mission operations plan.Desired systemPhase F CloseoutTo implement the systems decommissioning/disposal plan developed in Phase E and perform analyses of the returned data and any returned samples.Product closeoutDuring Phase Athe recursive use of the SE engine is continued,this time taking the concepts and draft key requirements that were developed and validated during Pre-Phase A and fleshing them out to become the set of baseline system requirements and Concept of Operations(ConOps).During this phase,key areas of high risk might be simulated or prototyped to ensure that the concepts and requirements being developed are good ones and to identify verification and validation tools and techniques that will be needed in later phases.During Phase B the SE engine is applied recursively to further mature requirements for all products in the developing product tree,develop ConOps preliminary designs,and perform feasibility analysis of the verification and validation concepts to ensure the designs will likely be able to meet their requirements.Phase C again uses the left side of the SE engine to finalize all requirement updates,finalize ConOps,develop the final designs to the lowest level of the product tree,and begin fabrication.Phase D uses the right side of the SE engine to recursively perform the final implementation,integration,verification,and validation of the end product,and at the final pass,transition the end product to the user.The technical management processes of the SE engine are used in Phases E and F to monitor performance;control configuration;and make decisions associated with the operations,sustaining engineering,and closeout of the system.Any new capabilities or upgrades of the existing system would reenter the SE engine as new developments.SE engine tracking icon3.Example PremiseNASA decides that there is a need for a transportation system that will act like a“truck”to carry large pieces of equipment and crew into Low Earth Orbit(LEO).Referring back to the project life cycle,the project first enters the Pre-Phase A.Feasible:combinations of simulations,mockups,analyses,or other like means3.1 Phase A System Design PassesFirst PassTaking the preliminary concepts and drafting key system requirements developed during the Pre-Phase A activities,the SE engine is entered at the first process and used to determine who the product stakeholders are and what they want3.1 Phase A System Design PassesFirst PassAgency needs a“space truck”that will carry X tons of payload into LEO,accommodate a payload of so-and-so size,carry a crew of seven,etc.During this Phase A pass,these general concepts are detailed out and agreed to.The detailed expectations are then converted into good requirement statements3.1 Phase A System Design PassesFirst PassNext,using the requirements and the ConOps previously developed,logical decomposition models/diagrams are built up to help bring the requirements into perspective and to show their relationship.Finally,these diagrams,requirements,and ConOps documents are used to develop one or more feasible design solutions.3.1 Phase A System Design PassesFirst PassTo accomplish this transportation system,the best option in our trade studies is a three-part system:a reusable orbiter for the crew and cargo,a large external tank to hold the propellants,and two solid rocket boosters to give extra power for liftoff that can be recovered,refurbished,and reused.”3.1 Product hierarchy,tier 1:first passthrough the SE engineThe SE engine is completely recursive.That is,each of the three elements shown in the tier 1 diagram can now be considered a product of its own and the SE engine is therefore applied to each of the three elements separately.3.1 Phase A System Design Passes Second Passthe external tank requirements and the external tank ConOps(Concept of Operations)are established,and functional diagrams are developed as was done in the first pass with the STS product.Finally,these diagrams,requirements,and ConOps documents are used to develop some feasible design solutions for the external tank.3.1 Phase A System Design Passes Second PassTo build this external tank,since our trade studies showed the best option was to use cryogenic propellants,a tank for the liquid hydrogen will be needed as will another tank for the liquid oxygen,instrumentation,and an outer structure of aluminum coated with foam3.1 Phase A System Design Passes Second Pass3.1 Phase A System Design Passes Second Pass3.1 Phase A System Design PassesThird PassEach of the tier 2 elements is also considered an end product,and each undergoes another pass through the SE engine:Defining Stakeholdersgenerating ConOps,flowing down allocated requirements,generating new and derived requirements,developing functional diagrams and design solution concepts.3.1 Phase A System Design Passes Third Pass3.1 Phase A System Design Passes Passes 4 Through nFor this Phase A set of passes,this recursive process is continued for each product(model)on each tier down to the lowest level in the product tree.Note that in some projects it may not be feasible,given an estimated project cost and schedule,to perform this recursive process completely down to the smallest component during Phase APhase A System Design Passes Passes 4 Through nEngineering judgment must be used to determine what level of the product tier is feasible.Note that the lowest feasible level may occur at different tiers depending on the product-line complexity.For one product line it may occur at tier 2;whereas,for a more complex product,it could occur at tier 8.This also means that it will take different amounts of time to reach the bottom.Thus,for any given program or project,products will be at various stages of development.Phase A System Design Passes Passes 4 Through n3.2 Example Product Realization Passestwo types of products.the“end product”the one that will actually be delivered to the final user.the“phase product.”A phase product is generated within a particular life-cycle phase that helps move the project toward delivering a final product.3.2 Example Product Realization Passes oneEach of the phase for the bottom-level product tier is taken individually and realizedthat is,it is either bought,built,coded,or reused.3.2 Example Product Realization Passes oneeach of the realized models(phase products)are used to verify that the end product would likely meet the requirements as defined in the Technical Requirements Definition Process during the system design pass for this product.This shows the product would likely meet the“shall”statements that