ABSTRACT
SUMMARY This chapter presents the fundamentals of sensors and signal processing with an emphasis on mechatronics and applications. Sensors are used to measure signals that present changes in the time domain, for example, waveforms or digital steps. Different technologies have been developed over the years in order to sense many different physical quantities, such as temperature, flow, force, acceleration, position, sound pressure, and intensity of light, among others. Because of their varying nature, all these quantities may be measured under the form of waveforms. However, waveforms-which are analog signals —are often difficult to interpret in the time domain, and a transformation into the frequency domain is required. The Fourier transform still is the most popular technique used today for converting a time signal into a frequency spectrum. Nevertheless, in
5.5.3 Displacement Transducers ................................................................................... 184 5.5.3.1 LVDT ......................................................................................................... 184 5.5.3.2 Laser .......................................................................................................... 186 5.5.3.3 Proximity Probes ..................................................................................... 187 5.5.3.4 MEMS Sensors ......................................................................................... 188
5.5.4 Strain Gauges .......................................................................................................... 189 5.5.5 Load Cells ............................................................................................................... 193
5.5.5.1 Piezoelectric Force Transducers ............................................................ 193 5.5.5.2 Strain Gauge-Based Load Cells ............................................................ 195 5.5.5.3 Calibration of a Pair Force Transducer versus Accelerometer ......... 197
5.5.6 Temperature Sensors ............................................................................................. 198 5.5.6.1 Thermocouple .......................................................................................... 199 5.5.6.2 Thermistors and Resistance Thermometers ....................................... 199 5.5.6.3 Bimetallic Thermometers .......................................................................200 5.5.6.4 Infrared Sensors ......................................................................................200
