Multi-aperture beamforming for automated large structure inspection using ultrasonic phased arrays

Increasing the inspection quality and speed is essential in manufacturing applications, especially for large structures (e.g. modern aircrafts). Traditional ultrasonic manual scanning can be comprehensive, but lacks repeatability and is time-consuming. Several robotic non-destructive testing systems have been developed in recent years. Although high inspection rates have been achieved by the use of robotic arms, there is the need to furtherly increase the inspection speeds, to cope with the current industrial demands. For systems delivering robotic ultrasonic inspection through phased array probes, the current bottleneck is given by the time required to electrically fire all elements of the phased array probes, which limits the maximum scanning speed of the automated manipulators. This paper discusses the development of a multi-aperture beamforming method to focus the beam with multiple focusing points at a single firing. This work investigates this approach and the influence of different aperture excitations on the data quality. Experiments have been carried out using a 5MHz 32-element phased array probe manipulated by a KUKA robot. The results highlight the possibility to significantly improve the speed of automated inspection compared to linear beamforming, without compromising the inspection quality.