When talking torque measurement, ‘analogue’ or ‘digital’ become hardly required, being simply a matter of approach to operation, and that it must be the actual physical principles which are all-important.
Classification of sensors
In discussing sensing devices one must decide whether or not to classify them based on the physical property they utilize (including piezoelectric, photovoltaic, etc.) or according to the function they perform (including 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 would like to compare the merits of, say, two types of temperature sensors, if one has to look through separate sections on resistive, thermoelectric and semiconductor devices to create the comparison.
Alternatively, to try and differentiate devices by function often is commonly a relatively boring catalogue of numerous unrelated devices. The important thing on them is signals are transformed from one form to another one. It is additionally easy to discuss compression load cell from the functional viewpoint, under headings including length, temperature, etc., appropriate for somebody that actually would like to select or make use of a sensor for the application rather than just read around the subject.
The words ‘sensors’ and ‘transducers’ are both widely used within the description of measurement systems. The first kind is popular in the united states whereas the second is more often used in Europe. The choice of words in science is pretty important. In recent years we have seen a propensity to coin new words or 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 issue has become very apparent within the computer and microprocessor areas, where preciseness is particularly important, and can seriously confuse persons entering the topic.
The word ‘sensor’ is derived from sentire, meaning ‘to perceive’ and ‘transducer’ is from transducere meaning ‘to lead across’. A dictionary definition Chambers Twentieth Century) of ‘sensor’ is ‘a device that detects a big difference in a physical stimulus and turns it right into a signal which may be measured or recorded’; a corresponding concept of ‘transducer’ is ‘a device that transfers power in one system to another one within the same or perhaps in different form’.
A sensible distinction is by using ‘sensor’ for that sensing element itself, and ‘transducer’ for the sensing element plus any associated circuitry. For instance, thermistors are sensors, given that they react to a stimulus (changes its resistance with temperature), but only become transducers when connected in a bridge circuit to convert improvement in potential to deal with change in voltage, considering that the complete circuit then transduces through the thermal to the electrical domain. A solar cell is both a sensor and a transducer, since it responds to a stimulus (generates a current or voltage in response to radiation) as well as transducer from the radiant towards the electrical domain. It does not require any associated circuitry, though in practice an amplifier would usually be used. All transducers thus hkjrzk a sensor, and many (though not all) sensors will also be transducers.
The difference is quite small and once one actually uses a sensor (by making use of capability to it) it will become load cell. An interesting classification of devices can be accomplished by taking into consideration the many forms of energy or signal transfer.
The word ‘actuate’ means ‘to put in, or incite to, action’ and actuators are devices that make the display or observable output in a measurement system such as a light-emitting diode (LED) or moving coil meter. These are needless to say transducers used for output purposes, since they transduce from a single domain to another (ie. electrical to radiant for LEDs).