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ME886.3

Topic 1: System and System Design (I)

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What we design?

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1. What we design

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1. What we design

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1. What we design

My dream living room

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1. What we design

Courtesy to a friend of mine in China (N. Ouyang)

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1. What we design

We design everything. Design is to create a thing that is not existed.

Why we design?

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Why we design?

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Design things for purpose and there are three purposes:

1. Function: design a thing that can assist in a human’s activities.

2. Comfort: design a thing humans can feel comfortable with when interacting with the thing.3. Emotion: design a thing humans can change their emotion when interacting with the thing.

Things designed will have a mixture of function, comfort, and emotion.

The difference between design of an arts product and design of a non-arts product lies in that arts design is only for the purpose of emotion.

2. Why we design

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2. Why we design – cook is a design

Function: meet hungry and provide nutrition.Comfort: size and mechanical property of cookies.Emotion: graceful, clean, simple, light, positive, delicate.

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Different non-arts products can have different emphases on function, comfort and emotion. For example, for products such as industrial robots, their functions are more emphasized than human’s comfort or emotion. However, fashion products may put more emphasis on human’s emotion.

For non-arts products or products design, 80% of the total cost of a product is determined at the design stage.

2. Why we design

How we design?

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How we design?

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3. How we design

Explore and develop design science and technology.

First, unify the things to be designed; that is to say, having a theory to describe everything using one formalism – system.

Second, be aware of the nature of design which is: (a) open-ended, (b) empirical, and (c) iterative.

It is (a) because device technology and device are evolving, and constraints (conditions to function) keep changing.

It is (b) because design is an action of humans, the process of which has yet to be fully automated.

It is (c) because of the limitation of humans.

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Everything is a system!

To have a knowledge that is useful to design all these

different objects, we need to find a unified understanding of

everything, that is to system.

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4. Everything is a system

The goal is to find commonalities for various things we will be designing.

It can be achieved by viewing them as a system. Roughly, a system is

composed of a set of components. For example, a class room is

composed of chairs, tables, and electric facilities. This may be viewed as

an attribute of a system called “system is decomposable”.

The decomposable attribute of a thing is called the structural

attribute of the thing; or simply say, everything has a structure.

Putting together the commonalities of everything with a name that is

system. So the system is a generic everything or a generic model of

everything.

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4. Everything is a system

A model of X is not X. That is to say, a system or generic model of everything is just an abstraction of everything but not everything.

System of everything = system’s view of everything = generic model of everything.

A system or generic model includes the following common attributes: structure, state, behavior, principle, context, function.

FCBPSS Framework

Lin, Y and Zhang, WJ, 2004. “Towards a novel interface design framework: function-behavior-state paradigm,” International Journal of Human Computer Studies, Vol. 61, No. 3, pp. 259-297.

PrincipleContext

BehaviourFunction State

Structure

4. Everything is a system

Structure: a set of elements with their relationships. For example, 1 connects with 2, 2 connects with 3, 3 connects with 4, 4 connects with 1, but 2 and 4 have no direction connection, etc.

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1

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4. Everything is a system: an example

State

α

s

State variable (S)

State value (S=3)

There are many state variables or states for a system depending on your purpose or interest in a particular aspect of the system (e.g., kinematics, etc.). For instance, the stress in the component could also be a state, as if interest is in whether the system is broken or not

System behavior: the relation between the state variables (e.g., s=s(α))

System dynamic behavior: changes in states with respect to time. For example, α is a function of time, t, so s will be a function of t

4. Everything is a system: an example

Constrained by the ground

α

s

Principle: Polygon keep closure if the assembly is of integrity

Procedure: Step 1: assign vector to each edge of the polygon. Step 2: define vector with concerned state variables. Step 3: use math language to express the principle

What governs the behavior, e.g., the relation between s and α ?

4. Everything is a system: an example

021

iii seelel α

s

sll coscos 21

0sinsin 21 llS=S(α)

4. Everything is a system: an example

Context and function

Engine

Engine4. Everything is a system: example 1

Context and functionContext: The pre-condition, post-condition, and environment where a structure is placed.

Function: The usefulness of a structure with respect to the human, ecological, and technical system

Sewing machine

4. Everything is a system: example 2

Zhang and Lin’s FCBPSS: System or Generic Model of Everything

Principle

Context

Behaviour

Function

State

Structure

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FCBPSS makes design

more systematic

FCBPSS-based design process

Required function & context

Required state & behavior

Proposed structure

Compress the gas

Volume change –> displacement, rotation to translation

Slider-crank linkage

Synthesis Synthesis

AnalysisAnalysis

The above applies to conceptual, embodiment, and detailed design

Evaluation

FCBPSS-based design process

Required function & context

Required state & behavior

Proposed structure

Compress the gas

Volume change –> displacement, rotation to translation

Slider-crank linkage

Synthesis Synthesis

AnalysisAnalysis

The above activity loop implies that design iterates

Evaluation

FCBPSS-based design process

Required function & context

Required state & behavior

Proposed structure

When the evaluation shows unsatisfactory with the required function with context, there may be several options to adjust:

1.Change the required function2.Change the required context (or constraint or condition)3.Find new structures