Chapter 5 - Introduction to Sensors and Signal Processing

This chapter presents the fundamentals on sensors and signal processing, with emphasizes on Mechatronics and applications. Sensors are used to measure signals that present changes in the time domain, e.g. 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 found 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 signal processing, an analog-to-digital conversion (ADC) of the time signal is required at some stage, even if the Fourier transform is not used. When proper treatment and filtering approaches are not followed, important features in the signal may be attenuated and others may be falsely indicated. This chapter discusses how signals can be measured in order to avoid common pitfalls in signal acquisition and processing. The theoretical background is set in a comprehensive yet practical way.