instrument science[′in·strə·mənt ‚sī·əns]
The systematically organized body of general concepts and principles underlying the design, analysis, and application of instruments and instrument systems.
Instruments are very diverse in function and form. They differ according to measurands, range of magnitudes and the dynamic variations of the measurand, required accuracy, and nature and environment of application. Equally diverse is the range of technologies that can be used to realize a particular instrument function. To enable this information to be handled in such a way that it can be usefully applied to the design, analysis, or application of instruments, it must be organized on the basis of a systematic framework of general concepts and principles. This framework is termed instrument science.
The basis of instrument science is: first, the consideration of instruments as members of the general class of information machines; and second, an analysis and synthesis of the instruments as systems, applying the principles of system engineering.
There exists a wide class of machines whose function is to acquire, process, and feed out information. This class includes measuring instruments, control apparatus, communication equipment, and computers. These machines function by the transformation of an input physical variable into an output variable in such a way that the output is functionally related to the input. Thus the output carries information about the input. This basic principle of functioning determines the general features of the analysis and synthesis of information machines. See Computer, Control systems, Electrical communications
Instruments and indeed other forms of information machines are conveniently analyzed and synthesized as systems. A system is a set of interconnected components functioning as a unit. There is a set of general principles and techniques for treating complex entities as systems. It is known as the systems approach, and is based on the decomposition of the complex whole into individual components. The individual components are considered in the first instance in terms of function rather than form.
Considering systems, such as instruments, as structures of functional building blocks makes clear that a very wide variety of instruments can be constructed from a much smaller variety of building blocks organized into a small variety of basic structures, such as a chain or loop connection. Further, it makes clear that apparently different systems—say, electrical and mechanical, or physical and biological—are essentially analogous. See Systems analysis, Systems engineering