In Situ Plume Sensing With an Event-Based Vision Sensor (EVS) and AI Analysis
Author
Takatsuka, Susumu and Ueno, Hiroshi and Azumi, Hitoshi and Kawahara, Tomohiro and Koizumi, Akira
Abstract
In the vicinity of deep-sea mining collectors, highly turbid and turbulent environments are generated, raising concerns regarding the transport and ecological impacts of suspended particle plumes. However, conventional optical turbidity sensors and acoustic Doppler current profilers (ADCPs) have limited capability to resolve the highly dynamic and near-field plume processes occurring immediately around the collector.In this study, we directly observed the initial behavior of plume particles using an Event-based Vision Sensor (EVS) with millisecond-level temporal resolution. A field experiment was conducted during a collector operation in Saiki Bay, Japan, where an EVS was installed behind the collector to measure particle velocity vectors, flow direction distributions, fine-scale vortex structures, and particle size variations. Owing to its asynchronous event-based sensing principle, the EVS operates without saturation under highly turbid conditions and enables continuous tracking of rapid particle motion.The results show that particle velocities reached up to approximately 600 mm/s immediately after collector activation, accompanied by the formation of millimeter- to centimeter-scale vortical structures. Flow direction distributions varied markedly with operational modes, and particle size distributions rapidly simplified after operation ceased. In addition, some particles exhibited temporal variations in velocity, direction, and morphology, suggesting potential biological origin.These results demonstrate that EVS enables direct observation of near-field plume dynamics that are difficult to capture using conventional OBS or ADCP systems. Furthermore, horizontal dispersion measurements obtained by EVS complement settling characteristics derived from LISST-RTSSV, offering a pathway toward reducing uncertainties in initial plume conditions for environmental impact assessments.
