A fast tracking algorithm for estimating ultrasonic signal time of flight in drilled shafts using Active Shape Models

Drilled shaft is an important substructure foundation in building construction. A drilled shaft needs to be placed precisely in high accuracy and satisfy the diameter precision requirement. In order to measure the verticality and the diameter of a shaft, the M-superimposed Gaussian Echoes Model (GEM) is used to estimate the time of flight (TOF) of ultrasound. Compared to the conventional threshold and cross-correlation based methods, GEM method has higher resolution and higher signal-to-noise ratio. However, the GEM method is computational expensive. In this paper, we propose an Active Shape Models (ASMs) tracking based algorithm to estimate the time of flight (TOF) of the ultrasound testing inside a cylindrical container. It extracts the pattern of the first several arriving peaks and troughs in a more flexible way with better efficiency than GEM.