Space Systems Engineering

Transcription

1 Background of Systems Engineering NASA program planning phases Scheduled milestones Requirements document Work breakdown structure Technology readiness levels Project management tools Design reference missions and CONOPS Earned value management Risk tracking David L. Akin - All rights reserved

2 Schedule Updates Special lecture Friday 9/4 - Orbital Mechanics 1:00-2:30pm ITV1111 Special lecture Friday 9/11 - Rover Design 2 1:00-2:30pm ITV1111 No lectures on Tuesday 9/15 and Thursday 9/17 - meet with your preliminary design teams! 2

3 Assigned Groups for Initial Design Project Team Alpha Jayne Breitwieser Andrew Britton Kevin Davis Brandon Hall Marissa Intelisano Leon Manfredi Team Beta Jennifer Donaldson Taylor Feiereisel Zachary Gonnsen Brandon Litt Lauren Puglisi Team Gamma Gregory Holste Rodric Richenberg Ji-Hyoung Woo Wayne Yu Albert Zhou Team Delta James Doggett Justin Hill Samantha Lustig Christopher Mak Robert Wagner Timothy White Team Epsilon Kevin Buckley Ricardo Gutierrez Laura Meyer Elaine Petro Tut Gatyiel 3

4 Overview of Systems Engineering Developed to handle large, complex systems Geographically disparate Cutting-edge technologies Significant time/cost constraints Failure-critical First wide-spread applications in aerospace programs of the 1950 s (e.g., ICBMs) Rigorous, systematic approach to organization and record-keeping 4

5 NASA Lifecycle Overview 5

6 NASA Formulation Stage Overview 6

7 Space Systems Development Process Pre-Phase A Conceptual Design Phase Development of performance goals and requirements Establishment of Science Working Group (science missions) Trade studies of mission concepts Feasibility and preliminary cost analyses Request for Phase A proposals 7

8 Space Systems Development Process Pre-Phase A Phase A Preliminary Analysis Phase Proof of concept analyses Mission operations concepts Build vs. buy decisions Payload definition Selection of experimenters Detailed trajectory analysis Target program schedule RFP for Phase B studies 8

9 Space Systems Development Process Pre-Phase A Phase A Phase B Definition Phase Define baseline technical solutions Create requirements document Significant reviews: Systems Requirements Review Systems Design Review Non-Advocate Review Request for Phase C/D proposals 9

10 Historical Implications of Study Phases from J. A. Moody, ed., Metrics and Case Studies for Evaluating Engineering Designs Prentice-Hall,

11 Implementation Stage Overview 11

12 Space Systems Development Process Pre-Phase A Phase A Phase B Phase C/D Development Phase Detailed design process Cutting metal Test and analysis Significant reviews: Preliminary Design Review (PDR) Critical Design Review (CDR) Test Acceptance Review Flight Readiness Review Ends at launch of vehicle 12

13 The Space Systems Development Pre-Phase A Phase A Phase B Operations and End-of-Life Launch On-orbit Check-out Mission Operations Maintenance and Troubleshooting Failure monitoring End-of-life disposal Phase C/D Phase E/F 13

14 NASA Project Life Cycle - Milestones from NASA SP rev. 1, NASA Systems Engineering Handbook 14

15 NASA Project Life Cycle - Acronyms from NASA SP rev. 1, NASA Systems Engineering Handbook 15

16 ASUMD* Program Goals To design a astronaut support vehicle that is compatible with Constellation architecture and supports exploration objectives To design and develop a function prototype of the ASUMD for field testing in support of project design activities To disseminate information on ASUMD feasibility and utility to decision makers at NASA and elsewhere *(feel free come up with a better name...) 16

17 ASUMD Program Objectives Design a robotic rover capable of performing both autonomous and human-assistant tasks for lunar exploration Examine possible requirements for operational performance (e.g., range, speed, payload, capabilities) to maximize the likelihood of program approval and field utility The rover must be capable of launching on an Altair landing vehicle with minimal impact to critical down-payload 17

18 Requirements Document The bible of the design and development process Lists (clearly, unambiguously, numerically) what is required to successfully complete the program Requirements flow-down results in successively finer levels of detail May be subject to change as state of knowledge grows Critical tool for maintaining program budgets 18

19 Akin s Laws of Spacecraft Design - #13 Design is based on requirements. There's no justification for designing something one bit "better" than the requirements dictate. 19

20 Interface Control Documents Used to clearly specify interfaces (mechanical, electrical, data, etc.) between mating systems Critical since systems may not be fit-checked until assembled on-orbit! Success of a program may be driven by careful choices of interfaces KISS principle holds here ( keep it simple, stupid ) 20

21 Akin s Laws of Spacecraft Design - #15 (Shea's Law) The ability to improve a design occurs primarily at the interfaces. This is also the prime location for screwing it up. 21

22 Work Breakdown Structures Detailed outline of all tasks required to develop and operate the system Successively finer levels of detail Program (e.g., Constellation Program) Project (Lunar Exploration) Mission (Lunar Sortie Exploration) System (Pressurized Rover) Subsystem (Life Support System) Assembly (CO 2 Scrubber System) Subassembly, Component, Part,... 22

23 NASA Standard WBS Levels 1 & 2 23

24 Standard WBS for JPL Mission WBS Levels Project Management 01 Project Mgmnt Project Sys Eng 02 Project Sys Eng Mission Assurance 03 MA Mgmnt Science 04 Science Mgmnt Project Name Payload 05 P/L Mgmnt Flight System 06 Spacecraft Contract Mission Ops System 07 Mission Ops Mgmnt Launch System 08 Launch Services Business Mgmnt Mission & Nav Design System Safety Science Team P/L Sys Eng Flt Sys Mgmnt MOS Sys Eng Risk Mgmnt Project SW Eng Environments Sci Data Support Instrument Flt Sys - Sys Eng Ground Data Sys Project Plng Spt Information Systems Reliability Sci Investigatio & Ops Spt Instrument N Power Subsys Operations Review Support Config Mgmnt EEE Parts Eng Sci Environment Characterization Common P/L Systems Command & Data S/s MOS V&V Facilities Planetary Protection HW Q&A Education & Outreach P/L I&T Telecomm Subsys Foreign Travel/ITAR Launch Sys Eng SW Q&A Mechanical Subsys Project V&V Contamination Control Thermal Subsys SW IV&V Propulsion Subsys GN&C Subsys Spacecraft Flt SW Testbeds Spacecraft assembly test & verification ENAE 483/788D - Principles 06.12of Space Systems Design

25 Detail in JPL Flight Systems Column 1. Spacecraft Contract 2. Flight Systems Management 3. Flight Systems - Systems Engineering 4. Power Systems 5. Command and Data Handling Systems 6. Telecommunications Systems 7. Mechanical Systems 8. Thermal Systems 9. Propulsion Systems 10.Guidance, Navigation, and Control Systems 11.Spacecraft Flight Software 12.Testbeds 13.Spacecraft Assembly, Test, and Verification 25

26 Akin s Laws of Spacecraft Design - #24 It's called a "Work Breakdown Structure" because the Work remaining will grow until you have a Breakdown, unless you enforce some Structure on it. 26

27 Technology Readiness Levels TRL 9 TRL 8 TRL 7 TRL 6 TRL 5 TRL 4 TRL 3 TRL 2 TRL 1 Actual system flight proven through successful mission operations Actual system completed and flight qualified through test and demonstration System prototype demonstration in the real environment System/subsystem model or prototype demonstration in a relevant environment Component and/or breadboard validation in relevant environment Component and/or breadboard validation in laboratory environment Analytical and experimental critical function and/or characteristic proof-of-concept Technology concept and/or application formulated Basic principles observed and reported 27

28 PERT* Charts Task Title Task Duration Slack Time Earliest Starting Date Earliest Completion Date *Program Evaluation and Review Technique 28

29 The Critical Path and Slack Time 29

30 The Critical Path and Slack Time 30

31 Cascading Slack Time 31

32 Gantt* Charts ID Task Name D u r a t i o n S t a r t F i n i s h P r e d e c 1 Design Robot 4w Tue 9/3/02 Mon 9/30/02 2 Build Head 6w Tue 10/1/02 Mon 11/11/ Build Body 4w Tue 10/1/02 Mon 10/28/ Build Legs 3w Tue 10/1/02 Mon 10/21/ Assemble 2w Tue 11/12/02 Mon 11/25/02 2,3,4 September O c t o b e r N o v e m b e r 9/1 9/8 9/15 9/22 9/29 10/6 10/13 10/20 10/27 11/3 11/10 11/17 11/24 12/1 *developed by Charles Gantt in

33 Some Pitfalls of Project Management 33

34 Akin s Laws of Spacecraft Design - #23 The schedule you develop will seem like a complete work of fiction up until the time your customer fires you for not meeting it. 34

35 Design Reference Missions Description of canonical mission(s) for use in design processes Could take the form of a narrative, storyboard, pictogram, timeline, or combination thereof Greater degree of detail where needed (e.g., surface operations) Created by eventual users of the system ( stakeholders ) very early in development cycle 35

36 Concept of Operations Description of how the proposed system will accomplish the design reference mission(s) Will appear to be similar to DRM, but is a product of the design, rather than a driving requirement Frequently referred to as CONOPS, showing DOD origins 36

37 Space Systems Architecture Description of physical hardware, processes, and operations to perform DRM Term is used widely (e.g., software architecture, mission architecture, planning architecture ), but refers to basic configuration decisions Generally result of significant trade studies to compare options 37

38 ESAS Final Architecture/CONOPS 38

39 Earned Value Management Consider a simple program with four two-month tasks that are expected to cost various amounts $4 M $10 M $6 M $8 M $2M $7M $8M $7M $4M Planned monthly costs Months 39

40 Program Cost Accounting Traditionally monitored by burn rate - cumulative expenditures with time 25 Costs ($M) Cumulative Months 40

41 Earned Value Management - Month 1 In the first month, you complete 60% of task 1 and 10% of task 2 Actual costs for month 1 = $3 M EV=$3.4 M $4 M EV(1)=0.6*4=$2.4 M $10 M EV(2)=0.1*10=$1 M $6 M $8 M Months 41

42 Earned Value Management - Month 2 In the second month, you complete 100% of task 1 and 60% of task 2 Actual costs for month 2 = $10 M EV=$10 M $4 M EV(1)=1.0*4=$4 M $10 M EV(2)=0.6*10=$6 M $6 M $8 M Months 42

43 Earned Value Management - Month 3 In the third month, you complete 100% of task 1, 80% of task 2, and 40% of task 3 Actual costs for month 3 = $16 M EV=$14.4 M $4 M EV(1)=1.0*4=$4 M $10 M EV(2)=0.8*10=$8 M $6 M EV(3)=0.4*6=$2.4 M $8 M Months 43

44 Program Cost Accounting - Tracking Plotting actual costs vs. time shows how money is spent, but doesn t tell anything about how much work has been accomplished Costs ($M) Cumulative Actual Months 44

45 Program Cost Accounting - Tracking Earned value tracks accomplishments against their planned costs Variation shows schedule performance Costs ($M) Cumulative Earned Value Months 45

46 Program Cost Accounting - Tracking Comparing earned value to actual costs shows apples to apples comparison of money spent and value achieved Costs ($M) Cumulative Earned Value Actual Months 46

47 Decision Analysis Tools A number of different approaches exist, e.g. Pugh Matrices Quality Function Deployment Analytic Hierarchy Process Generally provide a way to make decisions where no single clear analytical metric exists - quantifying opinions Allows use of subjective rankings between criteria to create numerical weightings Not a substitute for rigorous analysis! 47

48 Risk Matrix 48

49 References (Available on Web Site) NASA Systems Engineering Handbook - SP June, 1995 [2.3 Mb, 164 pgs.] (Obsolete, but nice description of NASA's systems engineering approach) NASA Systems Engineering Processes and Requirements - NPR A - March 26, 2007 [3.6 Mb, 97 pgs.] (Current version - pages are almost impossible to read without a magnifying glass) NASA Space Flight Program and Project Management Requirements - NPR D - March 6, 2007 [2.7 Mb, 50 pgs.] (Current version - pages are almost impossible to read without a magnifying glass) NASA Program and Project Management Processes and Requirements - NPR C - March 22, 2005 [1.9 Mb, 174 pgs.] (Older, superceded version, but includes more figures and is readable by mere mortals) NASA Goddard Space Flight Center Procedures and Guidelines: Systems Engineering - GPG B [1.7 Mb, 31 pgs.] NASA Goddard Space Flight Center Mission Design Processes (The "Green Book") [860 Kb, 54 pgs.] 49