A Novel Use of Normally Autonomous Subsea Drones in Direct ROV Mode for Shallow Water Pipeline Surveys

Abstract This paper describes an innovative method of undertaking pipeline and seabed surveys by adapting an otherwise autonomous underwater inspection drone (UID) to operate in a tether-less human-operated ROV mode which can be launched and recovered and operated remotely at a long distance from a lay vessel, or small support vessel, without need for a large Multi-role Support Vessel (MSV). A normally-autonomous subsea drone is adapted by using a surface buoy with a small data cable to the vehicle and with telemetry to enable direct control with real-time data and video feed to a nearby vessel or a remote control centre via Wi-Fi, cellular or satellite link. The vehicle is fitted with its standard integral onboard survey sensors such as Mult-Beam Echosounder Sonar, dual CathX Ocean UHD camera system, enabling geolocation and 3D point-cloud reconstruction and metrology if required, multi-sensor leak detection, optical automatic pipe-tracking and Inertial Navigation System, hydrography sensors; USBL acoustic position for independent positional information. The advantages of operating the UID in human-operated ROV mode over a classic ROV are: Disconnects the vehicle from the offshore platform or support vessel. Meaning that the vehicle can be operated in direct human operated ROV mode from long distance by way of Wi-Fi, 4G/5G cellular network or by satellite comms from the buoy.The surface buoy, in conjunction with USBL transponders on both the vehicle and the buoy enables independent visual and acoustic tracking from a nearby vessel, thus alleviating any security concerns.The dual UHD camera system (by CathX Ocean) enables extremely high-definition video quality as well as photogrammetric acquisition of geo-referenced point-cloud data, thus enabling highly accurate metrology and 3D model reconstruction.The built-in MBES system in combination with the point-cloud video data can be overlaid to provide a multi-source seabed and pipeline/structure geo-referenced image.The autonomous nature of the drone can allow it to automatically acquire and maintain track of the target pipeline or structure, reducing the need for skilled human navigation.Provides a technological and regulatory pathway to eventual full autonomous operations if desired.Can operate as a "force multiplier" by allowing parallel working in an area with say a conventional ROV or USV. The adaptation for use of UID/AUV in ROV mode combines many of the technical advantages of the autonomous drone such as significantly better video and data acquisition as well as the elimination of large support vess ls to be in close proximity, with the advantages of real-time control and video / data acquisition, whilst also addressing many security concerns related to remote underwater vehicles.