Examples of the Design of Measurement Systems
In this final chapter, we describe the needs for, the systems design philosophies and the means of realizing systems used for measurement-a self-nulling, microdegree polarimeter to measure glucose in bioreactors; the location and intensity of partial discharges in the insulation of coaxial, high voltage, power cables; design of a closed loop, constant phase, pulsed laser velocimeter; design of capacitive sensors for the detection of hidden objects. These four systems have been chosen to illustrate certain design principles, as well as to describe diverse, measurement systems. The author and his graduate students have designed and developed these unique
measurement systems. Therefore, their designs reflect their personal bias toward certain circuit architectures and manufacturers’ components. It is well appreciated that systems design in electrical engineering is an art as well as a science. The designer must balance criteria on system performance with cost and ease of manufacturing, safety, system reliability, ergonomics, aesthetics and environmental concerns. There are often several designs that can lead to the same end product, and no clear set of factors appears to favor one design over the others. It is in these fuzzy cases that a designer has greater freedom to show personal preferences (i.e. exhibit his or her ‘design style’). In the first design example given below, we describe the need for, the design approach
to, the specifications for, and a critique of, the performance of a partial discharge measurement system.