Optimization: Technical Performance Allocation EMIS 8340 Systems Engineering Tool—applying tools to engineering systems Optimization: Technical Performance Allocation Mark E. Sampson

Allocatable (Weight, Cost,…) Requirement Types… Allocatable (Weight, Cost,…) Non-Allocatable (material/process standards that apply to everything) …shall be painted green …shall be written in Mil-Std 1750 compliant ADA …let’s talk about the interesting ones… [DSMC 1986 6.4]

Requirements Allocation…the big picture Captured requirements… Linking requirement to functions… Functions linked to physical alternatives/architectures… …keep going until realizable …requirements flow thru system & documented in allocation matrix R R R R R Battery Motor Processor Drive Allocation Matrix R Func1 Battery R Battery R Func2 Motor [SE Handbook 9.2 ] [DSMC 1986 6.4]

Technical Budgets/Targets/Design Constraints Come from external interfaces, drivers, constraints… “How much” coming from functions Allocated/divided up among design alternatives Quantifiable requirements like: weight power thru-put cost error … Example allocation flow-down: System-transmit collected data in real time to remote ground site Segment-provide wideband data link from spacecraft to relay Element-provide 10Mhz link at 17Ghz Sub-system-provide 10Mhz link at 17Ghz with 10W effective radiated power for 20 minutes per orbit revolution [SE Handbook 9.2.2] [Lacy 1992]

Flowing-down Technical Budgets/Constraints… Tools are an important part of this process... Math Models Excel Tracing tools with extensions… A few SE tools include integrated budgeting (SLATE, Cradle-SEE,…) SLATE Technical Budgeting Demo… [SE Handbook 9.2.2] [DSMC 1986 6.4.4]

Costing…Design to Cost, Life Cycle Costing,… Predicting the cost of your system Using it as critical parameter for choosing alternatives Apparently we aren’t very good at predicting how much something will cost…particularly in software: GAO: “only 2% of software is usable exactly as delivered” Standish: “53% of projects will cost 189% of estimates” …either we are poor at executing or we are poor at estimating Engineered Costing relies on bottom-up rollups of tasks, etc. Analogs—just like this other one Rules-of-thumb—test costs 25% of manufacturing Validated/Modeled rules-of-thumb— Parametric Cost Estimation Models [www.jfc.nasa.gov/bu2/] [DSMC 1986 17]

Costing…Parametric Cost Estimation Identifies Cost Estimating Relationships (CERs) & “logic” among those relationships to estimate costs. Cost Estimates are then validated/tested using statistical techniques A number of hardware/software cost models have been created: Price-H,-S,… (LMCO) REVIC COCOMO AMCM--missions SoftCost-R …and a systems model is under development… COSYSMO Dr. Barry Boehm (USC) Dr. Richardo Valerdi (MIT/UofA) Present/Demo Unmanned Mission Non-recurring Cost Model [www.jfc.nasa.gov/bu2/]