Underwater robots, especially remotely operated vehicles (ROVs), according to the US Navy’s UUV Master Plan, are defined as “a self-propelled submersible whose operation is fully autonomous (with pre-programmed or real-time adaptive mission control) or under minimal supervisory control and is not connected except possibly for data links with a fiber optic cable. “
More specifically, remotely operated underwater vehicles – typically known as ROVs – are robotic vehicles designed to perform different tasks in extreme conditions. These unmanned, submersible and self-propelled platforms whose control and energization, as well as the transmission in real time of the information collected, is carried out by means of an umbilical cable while they are operated from the surface by a specialist pilot.
The use of these vehicles has gained increasing importance in many underwater activities due to the low level of exposure that ROV pilots have compared to the risks associated with diving at great depths, confined spaces, high geographical altitudes and long times.
These vehicles are used for a wide variety of operations, from diver support to heavy underwater construction. The market is substantially segmented into four broad categories based on vehicle size and capabilities:
- Observation ROV: These vehicles range from the smallest micro-ROVs to vehicles that can weigh up to 100 kg. ROVs of this classification are generally limited to depths less than 300 m due to the weight of their components, the required power supply, and the strength of the hull, which imposes limitations on the size of the vehicle.
- Medium-size ROVs: These vehicles can weigh up to 1,000 kg. They are typically a more in-depth classification version of observation ones, with enough power delivery components, telemetry options, and helmets capable of achieving greater depths, as well as umbilical lengths.
- Work Class ROVs: Vehicles in this category are generally heavy electromechanical vehicles that run on high voltage circuits. The power delivered to the vehicle from the surface is generally immediately switched to mechanical (hydraulic) power on the vehicle itself for locomotion, as all necessary tools and handling functions are in place.
- Special-purpose vehicles: these are vehicles that are not included in the main categories of ROVs because they are not designed to navigate, but to carry out special tasks under water such as digging trenches or burying elements.
Advantages of using ROVs
Broadly speaking, underwater robots play an important role in the offshore oil and gas industry, underwater asset management, defense, maritime search and rescue, oceanographic research, underwater archeology and environmental monitoring. The emerging field of deep-sea mining will drive ROV capabilities to unprecedented levels. The development of underwater robotics is an active research and development field with a promising industrial application, as it represents a sustainable solution for inspection, characterization, intervention and remediation that minimizes risks and intervention times.
There are an extensive number of benefits inherent to the use of remotely operated vehicles, including:
- In the case of confined spaces (tunnels, pipes, caverns, etc.), the ability to inspect from a single access point
- In the context of structures for conducting water for human consumption or electricity generation, it prevents the emptying of tunnels and pipes, allowing a detailed diagnosis of their condition to be obtained, eliminating the high risk of collapse associated with extreme changes in pressure conditions.
- Minimizes or completely eliminates the requirement for divers to enter confined spaces, further allowing the ability to operate without limits imposed by autonomy
- It represents a great tool for the periodic inspection of underwater assets and evaluating variations attributable to corrosion processes, fouling, geological activity, loss of flow due to accumulated sediments, detachments or deformations, among others.
- All information collected is geo-referenced, so the position of the elements and registered features is precisely known.
- Compact ROV equipment allows access to spaces with diameters from 50 cm
- The generated models allow the study sites to be fully evaluated, unlike filmic or photographic records
- The sonar technology used allows to achieve detailed characterization and modeling even in low or no visibility conditions