Application of morphological operators as envelope extractors for impulsive-type periodic signals

Impulsive-type periodic signals characterise the vibration response of machines subjected to frequent defects or wear of typical machine parts, like bearings or gears. Processing of the above signals entirely in the time domain is considered, using morphological analysis. The basic morphological operators (dilation, erosion, opening, closing) are used for construction of the envelope of impulsive-type periodic vibration signals. The effect of the type of the morphological operator and of the structuring element on the shape of the envelope is examined, The basic idea is to extract information from the time-domain shape of the signal, corresponding to the initial impulse series. The procedure is evaluated using simulated impulsive signals, as well as vibration signals, measured on two defective bearings of an industrial installation, which presents, respectively, an outer race fault and an inner race fault. (C) 2003 Published by Elsevier Science Ltd.