1. Chapter 2 - Overview of the Systems Engineering Design Process1 Aerospace Systems Engineering Chapter 2 - Overview of the Systems Engineering Design Process By Dr. Sartuk KARASOY Middle East Technical University skarasoy@metu.edu.tr The viewgraphs are mainly courtesy of Dr. Dennis Buede.

2. Chapter 2 - Overview of the Systems Engineering Design Process2 Key Terms System: set of components (subsystems, segments) acting together to achieve a set of common objectives via the accomplishment of a set of tasks. System Task or Function: set of functions that must be performed to achieve a specific objective. Human-designed System:  specially defined set of segments (hardware, software, physical entities, humans, facilities) acting as planned  via a set of interfaces, which are designed to connect the components,  to achieve a common mission or fundamental objective (i.e., a set of specially defined objectives),  subject to a set of constraints,  through the accomplishment of a predetermined set of functions.

3. Chapter 2 - Overview of the Systems Engineering Design Process3 External Systems & Context Figure 2.1

4. Chapter 2 - Overview of the Systems Engineering Design Process4 Functions of the Design Process Design FunctionMajor InputsMajor Outputs Define system-level design problem Develop system functional architecture Develop system physical architecture Develop system operational architecture Develop interface architecture Develop qualification system for the system Stakeholders’ inputs Originating requirements Operational concept Originating requirements Functional architecture Physical architecture Interface architecture Draft operational architecture Originating requirements Systems requirements Originating requirements Operational concept Functional Architecture Physical architecture Operational architecture Interface architecture Qualification system Design documentation Table 2.1

5. Chapter 2 - Overview of the Systems Engineering Design Process5 Functions of the System-Level Design Problem Design FunctionMajor InputsMajor Outputs Develop operational conceptStakeholders’ inputsOperational concept Define system boundary with external systems diagram Operational conceptSystem boundary, inputs, and outputs Develop system objectives hierarchy Operational concept Stakeholders’ inputs Objectives hierarchy Develop, analyze, and refine requirements (originating and system) Operational concept System boundary, inputs, and outputs Objectives hierarchy Stakeholders’ inputs Originating and systems requirements Ensure requirements feasibility Originating and systems requirements Systems engineering team’s inputs Design feasibility Define the test system requirements Originating and systems requirements Stakeholders’ inputs Test system requirements Obtain approval of system documentation Originating and systems requirements Originating and system requirements documents Table 2.2

6. Chapter 2 - Overview of the Systems Engineering Design Process6 Functions of the Integration & Qualification Process Design FunctionMajor InputsMajor Outputs Conduct early validationStakeholders’ inputs Operational concept Originating requirements Derived requirements Validated requirements Validated operational concept Conduct integration and verification testing Configuration items (CIs) Components Derived requirements Verification testing document Verified components and system Conduct system validation testing Verified system Originating requirements Stakeholders’ inputs Validation testing document Validated system Conduct system acceptance testing Validated system Acceptance test plan Stakeholders’ inputs Acceptance testing document Accepted system Table 2.3

7. Chapter 2 - Overview of the Systems Engineering Design Process7 Key Concepts Operational Concept: vision, mission requirements, & scenarios External Systems Diagram: meta-system Objectives Hierarchy: cost, schedule & performance measures of effectiveness Requirements –Input/output –Technology & System-wide –Trade-off –System Qualification

8. Chapter 2 - Overview of the Systems Engineering Design Process8 Key Concepts (Cont.) Function: transformation by system of inputs into outputs Items: inputs & outputs of a system Components: subset of a system Interfaces: connection resource between systems and components Verification: determination that physical design meets requirements Validation: determination that right system has been developed Acceptance: determination that stakeholders accept system

9. Chapter 2 - Overview of the Systems Engineering Design Process9 Elevator Scenarios 1. Passengers (including mobility, visually, and hearing challenged) request up service, receive feedback that their request was accepted, receive input that the elevator car is approaching and then that an entry opportunity is available, enter the elevator car, request a floor, receive feedback that their request was accepted, receive feedback that the door is closing, receive feedback about the floors at which the elevator is stopping, receive feedback that an exit opportunity is available at the desired floor, and exit the elevator with no physical impediments. 2. Passenger enters the elevator car, as described in scenario 1, but finds an emergency situation before an exit opportunity is presented, and notifies the police or health authorities using communication equipment that is part of the elevator. Elevator maintenance personnel create an exit opportunity. 3. A maintenance person needs to repair an individual elevator car; the maintenance person places the elevator system in “partial maintenance” mode so that the other cars can continue to pick up passengers while the car(s) in question is (are) being diagnosed, repaired, and tested. After completion, the maintenance person places the elevator system in “full operation” mode. Table 2.4

10. Chapter 2 - Overview of the Systems Engineering Design Process10 Elevator External Systems Diagram (IDEF0) Figure 2.2

11. Chapter 2 - Overview of the Systems Engineering Design Process11 Elevator Objectives Hierarchy Figure 2.3 Major performance, schedule and cost characteristics time quality availability operating cost …

12. Chapter 2 - Overview of the Systems Engineering Design Process12 Requirements Hierarchy Input/Output Requirements Input Output External Interface Functional System-wide & Technology Requirements Technology Suitability Cost Schedule Trade-off Requirements Cost Performance Cost-Performance Qualification Requirements Observance Verification Plan Validation Plan Acceptance Plan

13. Chapter 2 - Overview of the Systems Engineering Design Process13 Elevator Requirements (Sample) 4.3 Originating requirements 4.3.5 Operational phase requirements 4.3.5.1 Input/output requirements 4.3.5.1.1 Input requirements 4.3.5.1.1.1 Emergency support inputs 4.3.5.1.1.1.1 The system shall support manual overrides 4.3.5.1.1.1.2 The elevator system shall allow passengers with a designated pass key to assume complete control of an elevator car 4.3.5.1.2 Output requirements 4.3.5.1.2.1 Passenger environment outputs 4.3.5.1.2.1.1 The elevator car shall have adequate illumination. 4.3.5.1.4 Functional requirements 4.3.5.1.4.1 The elevator shall accept passenger requests and provide feedback. 4.3.5.1.4.2 The elevator shall move passengers between floors safely and comfortably. 4.3.5.1.4.3 The system shall control elevator cars efficiently. 4.3.5.1.4.4 The system shall enable effective maintenance and servicing. 4.3.5.2 System-wide and technology requirements 4.3.5.2.1 The system MTBF shall be greater than 1 year. The design goal is 1.5 years. Failure is defined to be a complete inability to carry passengers. 4.3.5.2.2 The system MTTR shall be less than 8 hours. The design goal is 4 hours. Repair means the system is returned to full operating capacity. Table 2.5

14. Chapter 2 - Overview of the Systems Engineering Design Process14 Elevator System Function Figure 2.4

15. Chapter 2 - Overview of the Systems Engineering Design Process15 Elevator Functional Decomposition Figure 2.5

16. Chapter 2 - Overview of the Systems Engineering Design Process16 Elevator Physical Architecture Figure 2.6

17. Chapter 2 - Overview of the Systems Engineering Design Process17 CORE: Systems Engineering Tool Entity – Relationship Database Classes – key concepts Relationships – architectures CORE Version 4.0 available in Aerospace Engineering Department Computer Lab