Synthetic aperture guided wave imaging using a mobile sensor platform

Miniature robotic vehicles are receiving increasing attention for use in Non-Destructive Evaluation (NDE) due to their attractiveness in terms of cost, safety and their accessibility to areas where manual inspection is not practical. Under ideal conditions, ultrasonic guided waves can propagate for significant distances across structures (10's meters) enabling rapid inspection of large areas. Furthermore guided waves can be generated by non-contact transducers which offers the possibility of couplant-free ultrasonic inspection. Combining non-contact guided wave transducers with mobile sensor platforms offers a unique opportunity for rapid reconfigurable inspection of large structures. This paper presents a two stage strategy for the inspection of structures made up of a series of plates sections, such as gas storage tanks. The first stage identifies the robot's position relative to the plate section on which it sits. The second stage inspects the plate using a synthetic array created from a series of measurements take across the width of the plate section.