A high frequency wide field of view ultrasonic sensor for short range collision avoidance applications on intervention class underwater vehicles

In this thesis a novel sensor design for intervention class AUVs and UUVs is described. The objective of this study is the development of sensor solutions that facilitate autonomous or remote guidance of underwater vehicles in close proximity to marine platforms, the seafloor or other hazards. In particular, this study addresses the need for improved sensing within the working envelope of intervention class vehicles. A literature review of the state-of-the-art in collision avoidance sensors identifies a number of performance and design shortfalls with currently available sensors as applied to intervention class UUVs and AUVs generally. This thesis then focuses on addressing these sensing shortfalls and in so doing strives to remove a practical impediment to the realisation of viable intervention AUVs. The sensor developed tested and evaluated provides a low-cost solution based on ultrasonic sensing principles. The new sensor design is characterised by a wide-angle spatial transmission pattern, good range resolution, short minimum detection range and fast response time. In target applications such as station keeping, docking and close quarters collision avoidance where reliable sensor coverage in the working envelope of a vehicle is of critical importance to vehicle safety, multiple ‘short range’ sensors with overlapping detection patterns can be used to augment data obtained using conventional ‘long range’ sonar and vision sensors.