No abstract

ResumenEste artículo presenta una arquitectura para el diseño conceptual de vehícu-los subacuáticos operados remotamente (ROV). La arquitectura propuesta está basada en una revisión extensa de literatura y la experiencia obtenida durante 20 años con el desarrollo de tres sistemas ROV diseñados para misiones de inspección subacuática. El ROV se divide en cinco subsistemas: vehículo, estación en superficie, interfaz superficie/vehículo, sistema de control y software. Para cada uno de estos subsistemas se definen funciones y tareas, se enuncian componentes, se establecen interrelaciones con otros subsistemas y se plantean alternativas comúnmente utilizadas. La delimitación de los subsistemas desde el diseño conceptual busca evitar problemas en las fases avanzadas del desarrollo del sistema robótico de exploración.Palabras clave: diseño de ROV; exploración subacuática; sistema robótico de exploración; vehículos submarinos autónomos

This work addresses the experimental study of the forces exerted during the extraction of sediment samples using push corers. The study aims to measure push and pull forces under different deployment conditions for corer speed and coring depth using sand, sandy silt and silt as sediment. To guarantee a repeatable automated process, a KUKA KR6 robot manipulator was used to extract the sample. The forces were measured using a bidirectional S-type load cell. The required data is extracted from the robot’s internal variables log and from the load cell’s data acquisition system. The raw data is processed to develop simplified models for the forces using linear regression which are further analyzed and tested. Finally, the results obtained are discussed in the context of core sampling and practical conclusions are drawn from the experiments.

Knowing whether a remotely operated vehicle (ROV) is able to operate at certain foreknown environmental conditions is a question relevant to different actors during the vehicle’s life cycle: during design stages, buying an ROV, planning operations, and performing an operation. This work addresses a framework to assess motion feasibility in ROVs by using the concept of ROV-dynamic positioning capability (ROV-DPCap). Within the proposed framework, the ROV-DPCap number is defined to measure motion capability, and ROV-DPCap plots are used to illustrate results, for quasi-static standard (L2) and site-specific (L2s) conditions, and dynamic standard (L3) and site-specific (L3s) conditions. Data are computed by steady-state or time-domain simulations from the ROV model, depending on the desired analysis. To illustrate the use of the framework, numerical examples for L2 and L2s motion feasibility analyses for NTNU’s ROV Minerva are provided. Motion feasibility can be used to know whether an ROV is appropriately designed for a specific operation and choose the appropriate one for a certain need, for instance, when designing the DP system components or planning an operation from the environmental data and ROV-specific information. As expected, predictions can be improved when more detailed information about the ROV appears; the same framework can be used to provide more detailed answers to motion feasibility-related questions. The results are likely to be straightforwardly understood by people whose work/training is ROV related and can interpret the graphic results for different operation scenarios.

Dynamic Positioning (DP) capability studies are used to assess if a vessel has sufficient thrust capacity to withstand environmental loads while keeping its position and orientation at a specified set-point or path. These studies are usually performed on ships and other DP-controlled surface vessels; consequently, standards and procedures for these are widely known. In this work, a methodology for conducting a DP capability study for Remotely Operated Vehicles (ROV) is presented. Due to the nature of ROV operations, a DP capability study should include different features that are not common to surface vessels. In this case, an ROV connected to a surface vessel through a tether is considered. During operation, the tether is subject to varying current loads that are accumulated along the water column and transferred to the vehicle. Therefore, the ROVs thrusters must be able to withstand, in addition to its own drag, three-dimensional loads due to three-dimensional currents and umbilical-related loads. To illustrate the methodology, two case studies are considered: the DP capability of an ROV that has to operate in the Colombian Caribbean and an existing ROV operating in the North Sea.