Systems Engineering in Aerospace and Defense

1
Systems Engineering in Aerospace and Defense

• By
• Don Bruyere
• Sr. Principal Electrical Engineer

2
Overview

• Answering Key Questions
• Organizational Structures in Aerospace
• Requirements Flow Model
• Developmental Model
• Engineering Support Organizations
• Overview of Risk Management

3
Key Questions of Systems Engineering
Effort
Martin, J. N.. Systems Engineering Handbook A
Process for Developing Systems and Products CRC
Press, Boston, Mass 2000 p. 13
4
Different Types of Business Organizations
President
President
Control Systems Analysis
Physical Design
Sensor Systems Development
Systems Engineering
Commercial Systems
Ground Systems
Weapons Systems
Functional Organization
Space Systems
Product Line Organization
C4I Systems
5
Aerospace Leans Primarily Towards Matrix
Organizations(Mixture of Product Line and
Functional Organization)
President
Control Systems Analysis
Physical Design
Sensor Systems Development
Systems Engineering
Commercial Systems
Ground Systems
Weapons Systems
Space Systems
C4I Systems
6
Strategic Competencies for Functional
Organizations Depends on Role in Engineering
Design
President
Control Systems Analysis
Physical Design
Sensor Systems Development
Systems Engineering
Commercial Systems
Ground Systems
Weapons Systems
Space Systems
C4I Systems

• ASIC Designer
• RF or Optical Mechanical
• Cir Board Materials

Grady, J. O.. Systems Validation and
Verification CRC Press, Boston, Mass 1997 p.
6
7
Classical Method of Requirements Flow
Customer Requirements
High Level Specification
Control System Specification
Com Link Specification
Sensor Specification
Propulsion Section Specification
INS Spec
Processor Spec
Boost Section Specification
Sustain Section Specification
GPS Spec
Software Spec
IR Sub Spec
8
Understanding Customer Requirements Requires
Dialog
Customer Requirement
Iterative Process During Concept Development
High Level Specification
Control System Specification
Com Link Specification
Sensor Specification
Propulsion Section Specification
INS Spec
Processor Spec
Boost Section Specification
Sustain Section Specification
GPS Spec
Software Spec
IR Sub Spec
9
System Level Requirements Drive Sub-System
Requirements
High Level Specification
Control System Specification
Sensor Specification
Com Link Specification
Propulsion Section Specification

• Design Trades
• Make in House vs. Buy Outside vs Reuse of
  Existing Technology
• Modeling (Fin. Elem. Anal., Fluid Flow Anal.,
  Thermal Models, Spice, Stereo Lith.)
• Drives Choices in Development Tools (Commonality
  Towards Legacy)
• Begins Development of Derived Requirements
• Further Derived from Primary Source Requirement
• Results from Choosing a Specific Implementation
• Requirements Must Be
• Necessary
• Traceable to Highest Level Requirement
• Measurable
• Verifiable
• Achievable

10
Classic Development Model for Sub-Component
Review Cycle
System Requirements Review
Critical Design Review
Preliminary Design Review
Operational Evaluation Technical Evaluation
Formal Qualification Testing
Functional Configuration Audit
Peer Review(s)
Bruyere,D. Sizing Throughput Requirements on
Real-Time Systems Embedded Systems Programming
p. 96-112
11
Subsystem Requirement Flow Begins Definition of
Design Modularity and Associated Interfaces
System
Customer Requirement
Modularity of Design and Well Defined Interfaces
Become Important in Paralleling Development Tasks
Propulsion
IR Tracker
GPS
Com Link
High Level Specification
Control Sec
Integration
Control System Specification
Com Link Specification
Sensor Specification
Propulsion Section Specification
INS Spec
Processor Spec
Boost Section Specification
Sustain Section Specification
GPS Spec
Software Spec
IR Sub Spec
12
Requirements Flow for Critical Items Sometimes
Accelerated
Customer Requirement
High Level Specification
Control System Specification
Com Link Specification
Sensor Specification
Propulsion Section Specification
INS Spec
Processor Spec
Boost Section Specification
Sustain Section Specification
GPS Spec
Software Spec
IR Subsystem Spec
13
Typical High Level Requirements

• Mission Definition
• Operational Environment
• Vibration
• Electro Magnetic Interference
• Weather (Salt water, desert heat, altitude
  pressure vs. air conditioned room)
• Interfaces to Outside
• Mounting
• Power Requirements
• Data I/O
• Physical Constraints
• Outer Dimension
• Weight Limitations
• Center of Gravity
• Per Unit Cost Goals Requirements

Customer Requirement
High Level Specification

• Performance Requirements
• Envelope
• Range(s)
• Adverse Conditions
• Operational Contingencies
• ilities
• Producability
• Reliability
• Survivability
• Safety
• Logistics

14
Typical Sub System Level Requirements
Customer Requirement
High Level Specification
Control System Specification
Com Link Specification
Sensor Specification
Propulsion Section Specification

• Responsiveness
• Stability
• Performance Envelope

• Range
• EP
• Directionality
• Resolution

• Range
• EP
• Directionality

• Specific Impulse
• Multi Phase
• Liquid vs. Solid (Main.)
• Safety

15
Sub-System Level Trades that Affect System Level
Requirements
Customer Requirement
Cost as an Independent Variable
High Level Specification

Control System Specification
Com Link Specification
Sensor Specification
Propulsion Section Specification

• Responsiveness
• Stability
• Performance Envelope

• Range
• EP
• Directionality
• Resolution

• Range
• EP
• Directionality

• Specific Impulse
• Multi Phase
• Liquid vs. Solid (Main.)
• Safety (IM)

16
Sub-System Level Trades that Affect System Level
Requirements(Continued)
Customer Requirement
More Cost Effective to Take Producability Into
Account Up Front
High Level Specification
Control System Specification
Com Link Specification
Sensor Specification
Propulsion Section Specification

• Responsiveness
• Stability
• Performance Envelope

• Range
• EP
• Directionality
• Resolution

• Range
• EP
• Directionality

• Specific Impulse
• Multi Phase
• Liquid vs. Solid (Main.)
• Safety (IM)

17
Interdependency of Sub-Component Requirements
To H/W Reqs

• Processor Requirements
• Throughput
• I/O Ports
• Memory Sizing
• Buss Bandwidth

IR Tracker
Optics
Servo
A good software developer has got to know his
limitations
Software
Processor
(Dirty) Harry Callihan, Magnum Force
Integration
18
Organizations That Work With Engineering to Help
Ensure Product and Process Stability/Consistency

• Quality Assurance
• Hardware
• Production
• Assembly and Critical Item Inspection
• Approve Design, Drawing and Planning Changes
• Ensure Design Changes are Requallified
• Development
• Process Oversight
• Software
• Process Enforcement
• Verification Oversight
• Configuration Management
• Identifies and Tracks Changes that Affect Product
  Form, Fit, and/or Function
• Becomes More Critical With Items that Employ
  Embedded Processors or Field Reprogrammable
  Devices

Separate CIs?
FPGA
Flash
mP
19
Managing Risk

• Risk Has Two Elements
• Probability
• Undesirable Consequences
• Mitigation Plan - Actions to Minimize Risk
• Contingency Plan - Minimizes Consequences

Vocabulary
Risk
Probability the chance that a given event will
occur if its a sure thing, then its a problem
(not a risk)
Consequence A risk impacts Performance,
Schedule, or Development, Unit, or Operations
Support Cost
20
Summary

• Primarily Matrix (Team Based) Organizations
• Historically Top Down Approach For Requirements
  Flow
• New Methods Are Being Experimented With
• Maintain Requirements Traceability Throughout
  Process
• Sub-Component Requirement Interdependency
  Unavoidable
• Rely on Engineering Support Organizations To Help
  Ensure Product and Process Consistency
• Risk Management Performed Formally at Program
  Level