Visual and Autonomous Survey of Hydrothermal Vents Using a Hovering‐Type AUV: Launching Hobalin Into the Western Offshore of Kumejima Island

Abstract

Autonomous underwater vehicles (AUVs) have become promising tools for marine geological surveys to collect information such as the topography of the seafloor and the location of hydrothermal plumes. Visual surveys and sampling are mainly conducted using human-occupied vehicles or remotely operated vehicles. To obtain detailed visual data more efficiently, a hovering-type AUV (Hobalin), which has the novel ability to autonomously navigate within a vent field, was developed to explore hydrothermal deposits. This vehicle was deployed in an active hydrothermal vent field located in the western offshore of Kumejima Island at a depth of approximately 1,400 m. Visual observations were performed with submillimeter image resolution via low-altitude navigation using still cameras. Moreover, a height estimation method for chimney structures was proposed utilizing an obstacle avoidance system composed of a sheet laser and a forward-looking camera with hovering maneuver capability. It was determined that hovering-type AUVs can facilitate the effective survey of hydrothermal vents and the acquired data can be utilized for subsequent sampling by human-occupied vehicles and remotely operated vehicles.

Development Timeline of the Autonomous Underwater Vehicle in Japan

“…In the national project Cross-ministerial Strategic Innovation Promotion Program [f] (SIP), which started in 2014, simultaneous operation of multiple AUVs was one of the major targets of technological achievement. Four new cruising AUVs and one hovering AUV, named Hobalin [18] (Fig. 15), were built.…”

Real-time detection of deep-sea hydrothermal plume based on machine vision and deep learning

“…In the past few years, AUV has played an essential role in the exploration of hydrothermal fields (German et al, 2008;Kumagai et al, 2010;Minami and Ohara, 2020). To obtain detailed visual data about seafloor hydrothermal activity more efficiently, Okamoto et al (2019) developed a hovering-type AUV named Hobalin to perform visual observations with submillimeter image resolution using still cameras. However, the shutters of the still cameras were triggered every 4 seconds and the images captured were then analyzed by experts after the recovery of the AUV.…”

On the Adaptation of an AUV into a Dedicated Platform for Close Range Imaging Survey Missions

“…Methods for improving the capabilities of AUVs' during autonomous visual mapping and survey missions were also recently introduced [14,15], and new concepts of low cost AUVs for close-to-seabed and high-resolution imaging in shallow water have been proposed [16,17]. Mature AUVs are currently being employed in visual surveys of archaeological sites [18], hydrothermal vents [19], coral reefs [20] and benthic communities [21].…”

“…Hovering type AUVs are optimized for precise motion control at low speed, mainly by employing several thrusters for motion control. Such AUVs are commonly designed with an ROV-like frame such as the Hobalin AUV [19] or with multiple streamlined hulls such as the Girona 500 [22], SeaBED [2], ABE [23] and TriMARES [24]. Operation of multiple-hull-shaped AUVs, however, may be cumbersome in a vicinity adjacent to a cluttered seabed or complex objects such as shipwrecks or coral reefs.…”