连杆机构英文文献和中文翻译(10)

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The implementation of both Dixon's and Suh's approaches to the design process is somewhat complicated. The interested reader is referred to the literature cited in the bib- liography to this chapter for more complete information.

1.7 MULTIPLE SOLUTIONS

Note that by the nature of the design process, there is not anyone correct answer or so- lution to any design problem. Unlike the structured "engineering textbook" problems, which most students are used to, there is no right answer "in the back of the book" for any real design problem. * There are as many potential solutions as there are designers willing to attempt them. Some solutions will be better than others, but many will work. Some will not! There is no "one right answer" in design engineering, which is what makes it interesting. The only way to determine the relative merits of various potential design solutions is by thorough analysis, which usually will include physical testing of constructed prototypes. Because this is a very expensive process, it is desirable to do as much analysis on paper, or in the computer, as possible before actually building the de- vice. Where feasible, mathematical models of the design, or parts of the design, should be created. These may take many forms, depending on the type of physical system in- volved. In the design of mechanisms and machines it is usually possible to write the equations for the rigid-body dynamics of the system, and solve them in "closed form" with (or without) a computer. Accounting for the elastic deformations of the members of the mechanism or machine usually requires more complicated approaches using finite difference techniques or the finite element method (FEM).

1.8 HUMAN FACTORS ENGINEERING

With few exceptions, all machines are designed to be used by humans. Even robots must be programmed by a human. Human factors engineering is the study of the human- machine interaction and is defined as an applied science that coordinates the design of devices, systems, and physical working conditions with the capacities and requirements of the worker. The machine designer must be aware of this subject and design devices to "fit the man" rather than expect the man to adapt to fit the machine. The term ergonom-

* A student once commented that "Life is an odd-numbered problem." This (slow) author had to ask for an explanation, which was: "The answer is not in the back of the book."

ics is synonymous with human factors engineering. We often see reference to the good or bad ergonomics of an automobile interior or a household appliance. A machine de- signed with poor ergonomics will be uncomfortable and tiring to use and may even be dangerous. (Have you programmed your VCR lately, or set its clock?)