University of Bristol demo robots monitor pipes with acoustic wave sensors

The team, led by Professor Bruce Drinkwater and Professor Anthony Croxford, developed an inspection procedure that allowed for the thorough examination of a three-meter steel pipe with various defects, including different-sized circular holes, a crack-like defect, and pits. This method, detailed in a study published in NDT and E International, utilises a network of independent robots, each carrying sensors capable of both emitting and receiving guided acoustic waves in pulse-echo mode.

The primary advantage of this approach is its minimal need for communication between robots, eliminating the necessity for synchronisation and potentially reducing data transfer costs through on-board processing. This reduction in communication requirements not only lowers the overall inspection costs but also improves efficiency. The inspection process is divided into two stages: defect detection and defect localisation.

Dr Jie Zhang, the lead author, highlights that while there are many robotic systems with integrated ultrasound sensors used for automated pipeline inspection, they often struggle with varying pipe cross-sections or complex network structures, leading to disruptions during inspection. This limitation makes them less suitable for general applications, being more tailored towards specific inspections of high-value assets like oil and gas pipelines.

The decreasing cost of mobile robots in recent years has opened up the possibility of deploying multiple robots for extensive area inspections. Dr Zhang's research explores how small inspection robots can be used for generic monitoring of structures, necessitating innovative inspection strategies, methodologies, and assessment procedures that are both cost-effective and efficient.

The study investigates the use of a network of robots, each equipped with a single omnidirectional guided acoustic wave transducer, considered for its simplicity and potential for integration into low-cost platforms. The employed methods are adaptable to various scenarios, enabling quick quantification of the impact of any detection or localisation method decisions. These techniques can be applied across different materials, pipe geometries, noise levels, or guided wave modes, facilitating a comprehensive exploration of sensor performance parameters, defect sizes and types, and operating modalities.

Furthermore, the team aims to assess the detection and localisation performance for specified inspection parameters, such as predicting the minimum detectable defect under certain probabilities of detection and false alarm.

The University of Bristol team is now looking to collaborate with industries to further develop their prototypes for practical pipe inspections. This project is part of the broader Pipebots initiative, funded by the UK's Engineering and Physical Sciences Research Council (EPSRC).