Polygonal Shapes Reconstruction from Acoustic Echoes Using a Mobile Sensor and Beamforming

Abstract

Mapping a structure, such as a metal plate in a ship hull, using acoustic echoes typically requires making assumptions on its shape (e.g. rectangular). This work introduces a more general approach based on beamforming to recover the geometry of arbitrary polygonal-shaped bounded areas from acoustic reflections. Our method only requires a single omni-directional emitter-receiver acoustic device mounted on a mobile platform. We apply beamforming to the acoustic measurements in the geometrical boundary space. We subsequently retrieve the edges from the beamforming results via the minimization of a regularized cost criterion, using a simulated annealing optimizer. We also design a boundary rejection criterion so that their exact number can be recovered based only on a specified upper bound. We assess our method on different geometries in a simulation environment and a real-world setting using ultrasonic guided waves measurements. The results demonstrate that it is efficient for achieving the targeted objectives.