Method for Measuring RPM of Fan by Using IR-UWB Radar

Continuous monitoring of the speed of fans in terms of rotations per minute (RPM) can offer several benefits such as fault diagnostics, the prognostics, and the amount of offered propulsion. Traditional methods rely on contact based measurement approaches where sensors are often installed on the fans. This study presents a non-contact method for RPM measurement based on the impulse radio ultra-wideband (IR-UWB) radar. Using radar, the fan position is first extracted and Fast Fourier Transform (FFT) is computed. Afterwards, the RPM of the fan was measured by extracting the peak in frequency domain. Using the proposed framework, the RPM of an electric fan was measured simultaneously by radars positioned at
$\mathbf{0}$
degree, 45 degrees and 90 degrees relative to the fan. The performance was compared with reference sensor and Mean Absolute Error (MAE), Root Mean Squared Error (RMSE) and Mean Absolute Percentage Error (MAPE) were reported. For radar at 0, 45 and 90 degrees, a Mean Absolute Percentage Error (MAPE) of 0.65%, 0.69% and 0.66% was observed for highest speed level of fan. Moreover, it was seen that radar positioned at 90 degrees can provide more accurate measurements, when compared to 0 degree and 45 degrees, irrespective of the speed of the fan.