KDD has developed an Autonomous Underwater Vehicle (AUV) AQUA EXPLORER 2 (AE2), the primary mission of which is to inspect buried underwater cables and to survey the seafloor. As AE2 has no tether cables between the vehicle and mother vessel, no large onboard equipment such as cable handling drums are needed. AE2 can therefore be operated from a small vessel, which drastically lowers the operation cost. AE2 communicates with the mother vessel through acoustic links. The onboard operator can monitor the status of the vehicle and the image of the seafloor through the acoustic link, and also can control the vehicle. Two sea tests were successfully performed. In these sea tests, AE2 succeeded in tracking an actual underwater cable laid in the Pacific Ocean. AE2 was also used to survey the seafloor for the construction of a new optical telecommunication cable system surrounding Japan. AE2 is also expected to be used in various underwater inspections other than cable inspection. This paper summarizes AE2 equipment and operation and also describes results of sea tests
Underwater telecommunications cable networks are expanding very rapidly making their installation and maintenance even more essential. This is especially true in shallow water where cables must be buried to avoid being damaged by fishing gear or boat anchors. Inspection of the sea floor prior to laying the cables and inspection of the buried cable is also essential for maintaining correct cable operation. Generally, remotely operated vehicles (or ROV) are used for cable inspection. However deep water inspection requires heavy duty ROVs and a large mother vessel which makes the cost of inspection extremely high. The authors believe that AUVs promise an inexpensive means for cable inspection. We previously developed a prototype AUV AE-1000 and succeeded in demonstrating its cable-tracking capability.