ME886.3 Topic 1: System and System Design (I)

1. ME886.3Topic 1: System and System Design (I)

2. What we design?

3. 1. What we design

4. 1. What we design

5. 1. What we design

6. 1. What we design • We design everything. Design is to create a thing that is not existed. Why we design?

7. 2. Why we design • 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.

8. 2. Why we design • 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 their value for 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. How we design?

9. 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.

10. 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. Everything is a system!

11. 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.

12. 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.

13. 4. Everything is a system 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. Function Behaviour State Structure Principle Context

14. 4. Everything is a system: an example 2 1 4 3 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.

15. State State variable (S) s State value (S=3) α 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 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

16. s α Constrained by the ground 4. Everything is a system: an example What governs the behavior, e.g., the relation between s and α ? 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

17. s α S=S(α) 4. Everything is a system: an example

18. 4. Everything is a system: an example Engine Context and function Engine

19. 4. Everything is a system: an example Context and function Context: 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

20. Zhang and Lin’s FCBPSS: System or Generic Model of Everything Function Context Behaviour Principle State Structure

21. FCBPSS makes design more systematic

22. FCBPSS-based design process Required function & context Required state & behavior Proposed structure Synthesis Synthesis Volume change –> displacement, rotation to translation Slider-crank linkage Compress the gas Analysis Analysis Evaluation The above applies to conceptual, embodiment, and detailed design

23. FCBPSS-based design process Required function & context Required state & behavior Proposed structure Synthesis Synthesis Volume change –> displacement, rotation to translation Slider-crank linkage Compress the gas Analysis Analysis Evaluation The above activity loop implies that design iterates

24. 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: • Change the required function • Change the required context (or constraint or condition) • Find new structures