When talking aerospace sensors, ‘analogue’ or ‘digital’ become hardly necessary, being simply a matter of method of operation, and that it is the actual physical principles that are all-important.
Classification of sensors. In discussing sensing devices one has to decide whether or not to classify them according to the physical property they normally use (such as piezoelectric, photovoltaic, etc.) or according to the function they perform (such as measurement of length, temperature, etc.). In the former case you can present a reasonably integrated view of the sensing process, however it is a bit disconcerting when one desires to compare the merits of, say, 2 kinds of 3 Axis Load Cell, if one has to look over separate sections on resistive, thermoelectric and semiconductor devices to make the comparison.
Alternatively, to try to differentiate devices by function often is commonly a relatively boring catalogue of numerous unrelated devices. The important thing on them is signals are transformed in one form to another. It is also possible to discuss Rotary Torque Sensor from your functional viewpoint, under headings such as length, temperature, etc., ideal for someone who actually wants to select or utilize a sensor for the application as opposed to just read around the subject.
The phrase ‘sensors’ and ‘transducers’ both are commonly used in the description of measurement systems. The former is popular in the united states whereas the second is a lot more often used in Europe. The option of words in science is rather important. Recently we have seen a propensity to coin new words or even to misuse (or misspell) existing words, and this can lead to considerable ambiguity and misunderstanding, and is likely to diminish the preciseness in the language. The challenge has become very apparent inside the computer and microprocessor areas, where preciseness is particularly important, and can seriously confuse persons entering the subject.
The phrase ‘sensor’ comes from sentire, meaning ‘to perceive’ and ‘transducer’ comes from transducere meaning ‘to lead across’. A dictionary definition Chambers 20th Century of ‘sensor’ is ‘a device that detects a change in a physical stimulus and turns it in to a signal which is often measured or recorded’; a corresponding concept of ‘transducer’ is ‘a device that transfers power from a single system to another inside the same or even in different form’.
An intelligent distinction is to apply ‘sensor’ for that sensing element itself, and ‘transducer’ for that sensing element plus any associated circuitry. For instance, thermistors are sensors, since they react to a stimulus (changes its resistance with temperature), but only become transducers when connected in a bridge circuit to transform improvement in potential to deal with alternation in voltage, because the complete circuit then transduces from your thermal to the electrical domain. A solar cell is both a sensor and a transducer, as it responds to some stimulus (creates a current or voltage in reaction to radiation) and also transducer through the radiant to the electrical domain. It does not require any associated circuitry, though in reality an amplifier would usually be applied. All transducers thus contain a sensor, and several (though not all) sensors are also transducers.
The distinction is pretty small, and as soon as one actually works with a sensor (by applying power to it) it becomes S Type Load Cell. A fascinating classification of devices can be achieved by thinking about the various hdjjdy of energy or signal transfer.
The phrase ‘actuate’ means ‘to placed into, or incite to, action’ and actuators are devices that produce the display or observable output in a measurement system such as a light-emitting diode (LED) or moving coil meter. These are obviously transducers used for output purposes, given that they transduce from a single domain to a different (ie. electrical to radiant for LEDs).