Engineering Cybernetics

by: Hsue-shen Tsien

Details

Year: 1954Description

Pages: 289

Publisher: McGraw-Hill Book Company, Inc. New York

The celebrated physicist and mathematician A. M. Ampere coined the word cybernétique to mean the science of civil government. Ampere's grandiose scheme of political sciences has not, and perhaps never will, come to fruition. In the meantime, conflict between governments with the use of force greatly accelerated the development of another branch of science, the science of control and guidance of mechanical and electrical systems.

It is thus perhaps ironical that Ampere's word should be borrowed by N. Wiener to name this new science, so important to modern warfare. The " cybernetics " of Wiener is the science of organization of mechanical and electrical components for stability and purposeful actions. A distinguishing feature of this new science is the total absence of considerations of energy, heat, and efficiency, which are so important in other natural sciences. In fact, the primary concern of cybernetics is on the qualitative aspects of the interrelations among the various components of a system and the synthetic behavior of the complete mechanism.

The purpose of " Engineering Cybernetics" is then to study those parts of the broad science of cybernetics which have direct engineering applications in designing controlled or guided systems. It certainly includes such topics usually treated in books on servomechanisms. But a wider range of topics is only one difference between engineering cybernetics and servomechanisms engineering. A deeper and thus more important difference lies in the fact that engineering cybernetics is an engineering science, while servomechanisms engineering is an engineering practice. An engineering science aims to organize the design principles used in engineering practice into a discipline and thus to exhibit the similarities between different areas of engineering practice and to emphasize the power of fundamental concepts. In short, an engineering science is predominated by theoretical analysis and very often uses the tool of advanced mathematics. A glance at the contents of this book makes this quite evident. The detailed construction and design of the components of the system the actual implementation of the theory are

almost never discussed. No gadget is mentioned.

What is the justification of this separation of the theory from the practice ? With knowledge of the very existence of various engineering sciences and their recent rapid development, such justification seems hardly necessary. Moreover, a specific example could be cited: Fluid mechanics exists as an engineering science separate from the practice of aerodynamics engineers, hydraulic engineers, meteorologists, and many others who use the results of investigations in fluid mechanics in their daily work. In fact, without fluid mechanists, the understanding and the utilization of supersonic flows would certainly be greatly delayed, to say the least. Therefore, the justification of establishing engineering cybernetics as an engineering science lies in the possibility that looking at things in broad outline and in an organized way often leads to fruitful new avenues of approach to old problems and gives new, unexpected vistas. At the present stage of multifarious developments in control and guidance engineering, there is a very real advantage in trying to grasp the full potentialities of this new science by a comprehensive survey of the whole field.

Therefore a discussion on engineering cybernetics should cover reasonably well all aspects of the science expected to have engineering applications and, in particular, should not avoid a topic for the mere reason of mathematical difficulties. This is all the more true when one realizes that the mathematical difficulties of any subject are usually quite artificial. With a little ^interpretation, the matter could generally be brought down to the level of a research engineer. The mathematical level of this book is then that of a student who has had a course in elements of mathematical analysis. Knowledge of complex integration, variational calculus, and ordinary differential equations forms the prerequisite for the study. On the other hand, no rigorous and elegant mathematical argument is introduced if a heuristic discussion suffices. Hence to the practicing electronics specialist, the treatment here must appear to be excessively " long-hair' but to a mathematician interested in this field, the treatment here may well appear to be amateurish. If indeed these are the only criticisms, then, with all due respect to them, the author shall feel that he has not failed in what he aimed to do.

Laplace transform, phase plane, root locus, power spectrum, optimalizing control, frequency response, RC circuit, servo, linear system, analog computer, unit circle, switching line, linear group, correlation function, However, phase space, probability distribution, mean deviation, limit cycle, nondimensional

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