Development of Thrusters and underwater connectors and their applications in ROVs

Abstract

Remotely Operated Underwater Vehicles (ROVs) are intended for observation and exploration of aquatic environments, such as inspection of reservoirs, submerged structures, oil and gas pipelines, support for maintenance of scientific equipment in riverbeds and oceans bed, as well as other activities in places with difficult access to humans. Equipped with cameras, they are operated by remote control by a team located on a nearby vessel and are able to send information about the vehicle as well as real-time images of the area where the ROV is located. An ROV consists basically of thrusters, connectors, several actuators, sensors, cameras, umbilical cable for communication, control electronics and its frame. The ROVs offered in the domestic market are imported. Besides the high price, subject to our import taxes, they present problems related to the high cost of maintenance, as well as the difficulty of replacing its elements. The group's experience identified three major technological bottlenecks in the development of a mid-sized inspection ROV: thrusters, umbilical cable and connectors. Reasonable quality thrusters are expensive and difficult to aquire. Cheaper thrusters have questionable performance and negative impact on umbilical and vehicle size. Another important bottleneck to be researched refers to the replacement of connectors and the umbilical cord, whose import difficulty is an important barrier to the development of ROVs and marinized equipment in general. The data transmission system must be feasible over longer distances. The main objective of the research is to develop national electrical thrusters, underwater connectors and umbilical cables to be used in inspections made ROVs. For the execution of this project, the ROV Mandí II was taken as reference. It was developed in the Laboratory of Unmanned Vehicles of the Polytechnic School of the University of São Paulo by members of the company Tétis Tecnologia Aquática. The starting point to use the ROV Mandí II thrusters, which are imported, as reference since they provide satisfactory power and compactness to the vehicle. The design proposed in this project selects the main components of the thruster so as to produce slightly better thrust than that produced by the imported and equivalent sized thruster. For the development of the connectors, given the depths involved in ROV applications, lower cost manufacturing processes, ie machining and transfer molding, will be adopted. The umbilical cord, already specified, will be ordered from a national company already identified. For this, will be investigated communication improvements between ROV and surface. Specifically, the application of VDSL2 technology will be addressed, in order to increase the communication distance, which is regularly limited by 100m using the Ethernet protocol. Expected results for this project include the development of a thruster prototype, connectors and umbilical cables capable of operating at a minimum depth of 200m.The project results will enable the company not only to supply underwater thrusters, but also to technical support and ROV maintenance on national soil. (AU)