Answer Happy

A triboelectric sensor with a single strip electrode in combination with the auto correlation signal processing algorithm and a microcontroller is used to measure the rotational speed of a dielectric shaft. (a) Sketch a block diagram showing the main elements of the rotational speed measurement system. [4 marks] (b) Explain the sensing mechanism of the triboelectric sensor and why the performance of the measurement system deteriorates under wet conditions. [4 marks] (c) With the aid of suitable equations, explain the principle of auto-correlation signal processing and how as it is applied to the rotational speed measurement. [3 marks] (d) Make a rough sketch of the auto-correlation function of the signal from the triboelectric sensor, given that the rotational speed is 1200 RPM (Revolutions Per Minute) and the first peak corresponding to the period of the signal is 0.90.