When talking torque measurement, ‘analogue’ or ‘digital’ become hardly important, being simply a matter of approach to operation, and that it is the underlying physical principles which can be all-important.
Classification of sensors
In discussing sensing devices one has to decide if you should classify them according to the physical property they use (including piezoelectric, photovoltaic, etc.) or according to the function they perform (such as measurement of length, temperature, etc.). Inside the former case you can present a reasonably integrated take a look at the sensing process, yet it is just a little disconcerting when one desires to compare the merits of, say, 2 kinds of temperature sensors, if one has to look through separate sections on resistive, thermoelectric and semiconductor devices to make the comparison.
Alternatively, to try and differentiate devices by function often is usually a relatively boring catalogue of numerous unrelated devices. The main thing about the subject is signals are transformed from a single form to another. It is also easy to discuss compression load cell from your functional viewpoint, under headings like length, temperature, etc., appropriate for somebody who actually would like to select or use a sensor for a particular application as opposed to just read round the subject.
The phrase ‘sensors’ and ‘transducers’ both are popular within the description of measurement systems. The former is popular in the united states whereas the latter is a lot more often used in Europe. The option of words in science is rather important. Recently we have seen an inclination to coin new words or misuse (or misspell) existing words, and this can lead to considerable ambiguity and misunderstanding, and is likely to diminish the preciseness from the language. The challenge has been very apparent inside the computer and microprocessor areas, where preciseness is extremely important, and may seriously confuse persons entering the subject.
The term ‘sensor’ hails 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 big difference in a physical stimulus and turns it into a signal which can be measured or recorded’; a corresponding concept of ‘transducer’ is ‘a device that transfers power from a single system to another one within the same or in different form’.
A smart distinction is to apply ‘sensor’ for that sensing element itself, and ‘transducer’ for that sensing element plus any associated circuitry. For example, thermistors are sensors, since they respond to a stimulus (changes its resistance with temperature), only become transducers when connected in a bridge circuit to transform improvement in effectiveness against alternation in voltage, because the complete circuit then transduces through the thermal for the electrical domain. A solar cell is both a sensor and a transducer, because it responds to a stimulus (creates a current or voltage in response to radiation) and in addition transducer from the radiant for the electrical domain. It can not require any associated circuitry, though in practice an amplifier would usually be used. All transducers thus hkjrzk a sensor, and lots of (though not every) sensors are also transducers.
The distinction is quite small, and as soon as one actually utilizes a sensor (by making use of power to it) it will become weight sensor. A fascinating classification of devices can be accomplished by taking into consideration the various forms of energy or signal transfer.
The phrase ‘actuate’ means ‘to put into, or incite to, action’ and actuators are devices that make the display or observable output in a measurement system like a light-emitting diode (LED) or moving coil meter. These are of course transducers used for output purposes, because they transduce from a single domain to another (ie. electrical to radiant for LEDs).