Development of a Floating LBL System and a Lightweight ROV for Sky to Water System

We have been developing a system for environmental research on shallow coastal waters. This is intended to monitor the global problem of coral reef bleaching. Our system consists of a multi-copter, a small ROV, and a USV that relays ROV-land communication. The ROV is stored in the USV and it is transported by the multi-copter. We call this system as Sky to Water System. By transporting these from land or ship by multi-copters, it is intended to investigate a wider area in a shorter time than divers do. These devices are carried by a multi-copter and can be dropped and recovered at any point on the sea by a lifting equipment that can be freely separated by a pilot's manipulation. The lifting equipment consists of a device with a working tip (we call it “probe”) attached to the multi-copter and a fixing device (we call it “funnel”) attached to the USV. Docking and detachment between the multi-copter and the USV are performed by inserting this probe into the funnel. So far, we have conducted several experiments on transportation of the device from land to water, and confirmed that the ROV can be transported if it is small, and that the separation mechanism works well. The floating LBL consists of at least three USVs that from a baseline of LBL. Each USV has a GNSS, an ultrasound receiver and a wireless communication device. By measuring the distance between the floating USVs and the distance between each USV and the ROV, the underwater coordinate can be determined real time. In this paper, we will explain the total concept of the sky to water system, especially about the newly fabricated light weight ROV and the floating LBL system with experimental result of underwater coordinate detection at sea.