As for differential transformers (i.e., LVDT and RVDT) transient displacement signals of a resolver can be extracted by demodulating its modulated outputs. This is accomplished by filtering out the carrier signal, thereby extracting the modulating signal. The two output signals uo1 and uo2 of a resolver are termed quadrature signals. Suppose that the carrier (primary) signal is
Some typical applications are:
1. Measurement and control of the gap between a robotic welding torch head and the work surface
2. Gauging the thickness of metal plates in manufacturing operations (e.g., rolling and forming)
3. Detecting surface irregularities in machined parts
4. Angular speed measurement at steady state, by counting the number of rotations per unit time
5. Measurement of vibration in rotating machinery, gears, bearings, etc.
6. Level detection (e.g., in the filling and chemical process industries)
7. Monitoring of bearing assembly processes
Some mutual-induction displacement transducers use the relative motion between the primary coil and the secondary coil to produce a change in flux linkage. Two such devices are the resolver and the synchrotransformer.
These are not variable-reluctance transducers because they do not employ a ferromagnetic moving element.