Instrument based on MEMS accelerometer for vibration and unbalance analysis in rotating machines

Abstract

The present work shows a low-cost instrument, based on MEMS accelerometer, specially designed to analyse unbalance in rotating machines. The acceleration signals, acquired using a sample rate of 817 Hz in two perpendicular axes at a free wheel shaft, were used to analyze the shaft vibration in the frequency domain by its Fast Fourier Transform (FFT). These signals from orthogonal accelerometers are also used to calculate the shaft unbalance. The instrument prototype was mounted on the shaft of a bicycle wheel, freely rotating at 120 rpm. Composing the characterization apparatus, some weights were introduced at the endings of a rim spokes to simulate a mechanical wheel unbalance. The experimental results show that both: vibration and unbalance can be measured successfully.