lecture systems thinking

8/17/2019 Lecture Systems Thinking

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AE 424 Aerospace Systems Engineering

Víctor Cámara

Facultad de Ingeniería

Universidad Autónoma de Chihuahua

This lecture was developed based on the NASA systems engineering course

AE 424 Aerospace Systems Engineering - Introduction


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System

Definition of System:

A system is a set of interacting or interdependent componentsworking together toward some common objective or purpose.

A system is composed of components, attributes, and relationships defined as:

a) Components are the operating parts of a system consisting of input,

process, and output.

b) Attributes are properties of a system, which characterize the system.

c)Relationships are the links between components and attributes.

A group of components of a system can themselves be another system

which is usually called subsystem. Each system can be a part or subsystemof a larger system.

A system and its components can be physical or nonphysical (e.g., softwaresystem, policy system).



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System

Classification of Systems:

Natural systems: solar system, river system, human body, food chain, etc.

Man-made systems: space station, satellite, aircraft, internet, banking system,

etc. Physical systems: a satellite, a vehicle, a railway system, etc.

Conceptual systems: a urban plan, an operating system, a language system, etc.

Static systems: having system structure but without activity such as a highway

network. Dynamic systems: having system structure with activities such as a traffic system.

Open systems: allows information, energy, and matter to cross its boundaries

such as business organizations and animals.

Closed systems: do not interact significantly with their environments such as

highway systems.

Both the open and closed systems exhibit the property of entropy which is a degree ofdisorganization in a system. A decrease in entropy occurs as order occurs. Human-madesystems are mostly intended to decrease entropy – creation of more orderly states fromless orderly states.

An example of exceptions is a weapon.



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Systems Thinkers …

• See the whole picture

• See the forest and the trees

• View from different perspectives

• Look for interdependencies

• Understand different models

• Think long term

• “Go wide” in thinking about cause and effectrelationships

• Think about potential benefits (opportunities) as well

as about unintended consequences (risks)• Focus on problem solving, not finding blame



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Systems Thinking – Why is it Important?

To understand and manage therequirements, and to develop the solution,we have to understand how it fits into thelarger system of which it is a part.

To get the ability to divide ComplexSystems into less complicated subsystems

AE 424 Aerospace Systems Engineering – Introduction


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COMPLEXITY

Complexity calls for:

– Division of labor – Division of knowledge (multidisciplinary projects)


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Systems Thinking – Why is it Important?

“Problems cannot be solved by the same level of thinking that created them.”

Albert Einstein

“Never forget that the system beingaddressed by one group of engineers isthe subsystem of another group and

the super-system of yet a third group.”* * Dennis M. Buede, The Engineering Design of Systems, 2000, John

Wiley & Sons.

As systems engineers, we must

consider products above, peerproducts, and subordinate products.



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Example of an Aerospace System

Space Shuttle Shuttle and launch vehicle



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Example of a System of Systems

A satellite with three enabling systems

Satellite of GPS Enabling

Interest System

Comun Enabling

System

Launch Vehicle Enabling System

AE 424 Aerospace Systems Engineering - Introduction 10


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Original Reasons for Systems Engineering

Systems of pieces built by differentsubsystem groups did not performas expected

• Often broke at the interfaces

Problems emerged and desired properties were not

realized when subsystems designed independently

were integrated

Managers and chief engineers tended to payattention ONLY to areas in which they were skilled

Developed systems were not usable

Cost overruns, schedule delays,Performance problems



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What Does “Systems Thinking” Involve?

1. Understanding the systemrequirements regardless of the

position of one’s product in thesystem decomposition hierarchy

2. Assessing the impact of systemrequirements on the subsystem

for which one is responsible

3. Assessing the impact of subsystemconstraints on the system

4. Assessing the impact of thesubsystem’s requirements on lowerlevel products before selecting asubsystem concept



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More and Better Systems Engineers

Why?

Trends in the development and design of newaerospace systems require more systemsengineering.

Large aerospace projects struggle with cost,schedule and technical performance.

Demographics - aging workforce and skill retention.

New aerospace systems are larger and/or morecomplex - requiring a higher percentage of systemsengineers.


R t T d i th D i d D l t


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Response to Trends in the Design and Developmentof New Aerospace Systems

New aerospace systems are more likely to have:

Technology development

A variety of subsystem technical maturities

Consider and reuse existing designs

Consider and incorporate COTS subsystems or components

Mandated implementations or subsystem vendors

Greater dependence on system models for design decisions

More stakeholders and institutional partners

More customer oversight and non-advocate review

‘System-of-systems’ requirements More people - project sizes are growing

Physically distributed design and manufacturing teams


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NASA and Industry Call For More and Better


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NASA and Industry Call For More and Better

Systems Engineers

All of the factors identified by NASA that contributed to program failure and significant cost overrun are systemsengineering factors, e.g.,

1) Inadequate requirements management

2) Poor systems engineering processes

3) Inadequate heritage design analyses in early phases

4) Inadequate systems-level risk management

Reference: NASA, Office of Program Analysis and Evaluation, Systems Engineering and InstitutionalTransitions Study, April 5, 2006. Reproduced in National Academies book - Building a Better NASAWorkforce: Meeting the Workforce Needs for the National Vision for Space Exploration.


lecture systems thinking

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