A theory of complexity, periodicity and the design axioms

被引:114
作者
Suh, NP [1 ]
机构
[1] MIT, Dept Mech Engn, Cambridge, MA 02139 USA
来源
RESEARCH IN ENGINEERING DESIGN-THEORY APPLICATIONS AND CONCURRENT ENGINEERING | 1999年 / 11卷 / 02期
关键词
axiomatic design; complexity; design axioms; periodicity;
D O I
10.1007/PL00003883
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
One of the topics that has received the attention of mathematicians scientists and engineers is the notion of complexity. The subject is still being debated, as it lades a common definition of complexity, concrete theories that can predict complex phenomena, and the mathematical tools that can deal with problems involving complexity. In axiomatic design, complexity is defined only when specific functional requirements or the exact nature of the query are defined. Complexity is defined as a measure of uncertainty in achieving a set of specific functions or functional requirements. Complexity is related to information, which is defined in terms of the probability of success of achieving the Functional Requirements (FRs). There are two classes of complexity: time-dependent complexity and time-independent complexity. There are two orthogonal components of time-independent complexity, i.e., real complexity and imaginary complexity. The vector sum is called absolute complexity. Real complexly of coupled design, is larger than that of uncoupled or decoupled designs. Imaginary complexity cart be reduced when the design matrix is known. As an example of time-independent imaginary complexity, the design of a printing machine based an xerography is discussed. There are two kinds of time-dependent real complexity: time-dependent combinatorial complexity and time-dependent periodic complexity. Using a robot-scheduling problem as an example, it is shown that a coupled design with a combinatorial complexity can be reduced to a decoupled design with periodic complexity The introduction of periodicity simplifies the design by making it deterministic, which requires much less information. Whenever a combinatorial complexity is converted to a periodic complexity, complexity and uncertainty is reduced and design simplified.
引用
收藏
页码:116 / 131
页数:16
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