Abstract
This paper provides a method of detecting cracks in concrete pillars by using an acceleration pickup. By giving a shock on the pillar with a hammer, several types of stationary waves generated in the pillar are observed with the sensor on one edge of the pillar. The method identifies the location of the cracks by modeling the sensor output as an output of a linear dynamic system with unknown parameters and applying a Kalman filter and the maximum likelihood method. Experiments show that two cracks in a concrete pillar of length 0.91m are detected within the localization error of 3～10mm.
