When talking aerospace sensors, ‘analogue’ or ‘digital’ become hardly necessary, being simply a matter of approach to operation, and that it is the underlying physical principles which are all-important.
Classification of sensors. In discussing sensing devices one must decide if you should classify them according to the physical property they use (such as piezoelectric, photovoltaic, etc.) or based on the function they perform (like measurement of length, temperature, etc.). Inside the former case you can present a reasonably integrated view of the sensing process, but it is just a little disconcerting when one wishes to compare the merits of, say, two kinds of Multi Axis Load Cell, if one has to examine separate sections on resistive, thermoelectric and semiconductor devices to help make the comparison.
Alternatively, to attempt to differentiate devices by function often is commonly a relatively boring catalogue of numerous unrelated devices. The main thing about them is signals are transformed from a single form to a different. Additionally it is possible to discuss Torque Transducer from the functional viewpoint, under headings such as length, temperature, etc., suitable for somebody that actually desires to select or use a sensor for a particular application as opposed to just read around the subject.
The text ‘sensors’ and ‘transducers’ are generally popular within the description of measurement systems. The first kind is popular in the USA whereas the second is a lot more often used in Europe. The choice of words in science is pretty important. In recent years there has been a propensity to coin new words or misuse (or misspell) existing words, and this may lead to considerable ambiguity and misunderstanding, and tends to diminish the preciseness of the language. The matter continues to be very apparent inside the computer and microprocessor areas, where preciseness is especially important, and will seriously confuse persons entering the niche.
The term ‘sensor’ comes from sentire, meaning ‘to perceive’ and ‘transducer’ originates 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 can be measured or recorded’; a corresponding concept of ‘transducer’ is ‘a device that transfers power from one system to another one in the same or in different form’.
An intelligent distinction is to apply ‘sensor’ for that sensing element itself, and ‘transducer’ for the sensing element plus any associated circuitry. As an example, thermistors are sensors, because they respond to a stimulus (changes its resistance with temperature), only become transducers when connected in a bridge circuit to convert change in potential to deal with alternation in voltage, since the complete circuit then transduces through the thermal to the electrical domain. A solar cell is both a sensor and a transducer, because it responds to your stimulus (produces a current or voltage in response to radiation) as well as transducer through the radiant for the electrical domain. It can not require any associated circuitry, though in reality an amplifier would usually be applied. All transducers thus include a sensor, and lots of (though its not all) sensors can also be transducers.
The difference is pretty small and the moment one actually works with a sensor (by applying power to it) it might be Miniature Force Sensor. An interesting classification of devices may be accomplished by considering the various hdjjdy of energy or signal transfer.
The term ‘actuate’ means ‘to put into, or incite to, action’ and actuators are devices that produce the display or observable output in a measurement system like a light-emitting diode (LED) or moving coil meter. They are obviously transducers employed for output purposes, since they transduce in one domain to another one (ie. electrical to radiant for LEDs).