Displacement and Velocity Measurements

Why do we need instrumentation? Because our human senses are inadequate. Vibratory displacements, for instance, may be only a few micro-inches, far too small for our fingertips to sense reliably. Yet we need to know dynamic displacements. Quoting William Thomson (Lord Kelvin): When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind. It may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science.
Our measurement systems need to be accurate. Our measurements should be repeatable. They should avoid bias. In many situations we need not only precision but may also need remote and automatic sensing and control. Some environments are too severe for human tolerance. Some events are too brief for our senses, nerve pathways and brains. Finally, legal, financial and/or engineering need for measurements may exist.

6.1 Why do we need instrumentation?

6.2 Analogy with humans
6.3 How do we describe an events severity?
6.4 Linearity
6.5 Distributions
6.6 Importance of measurement certainty
6.7 Metrology terms 6
6.8 Its ok to question the lab
6.9 Visual displacement indicators
6.10 Displacement sensors and recorders
6.11 Non-contact displacement-sensing lasers
6.12 Velocity sensors
6.13 Vibration switches
6.14 Conclusions