Robotics

Modular ROVs quickly adapt to risky underwater missions

17th May 2021
Joe Bush

Underwater explorations and targeted missions have always been risky, time-consuming and costly. However, VideoRay tethered, underwater remotely operated vehicles (ROVs) are becoming ubiquitous for today’s toughest aquatic missions. From mine countermeasures and underwater search and rescue to port security and surveillance, VideoRay ROVs are helping reduce risk and achieve results faster and easier. Vicor’s portfolio of DC/DC power conversion modules are being used on the VideoRay Modular ROVs.

Where sustained, underwater inspection or exploration is required, the fleet of VideoRay ROVs is the safest and most effective way to maintain security, support salvage efforts and uncover secrets of the ocean. Video-equipped ROVs can reach hard-to-access underwater locations at extreme depths for extended periods. To be effective, ROVs require a robust, high density power delivery network (PDN) that enables the necessary thrust to withstand shifting ocean currents and provides a steady view of surroundings while having space for payloads to accomplish mission specific activities.

Founded in 1999, VideoRay is at the forefront of underwater ROV innovation and has established itself as a worldwide leader in observation-class underwater ROVs that are widely deployed across every continent. VideoRay underwater ROVs are optimised for a wide range of applications, including search and rescue, security and anti-terrorism, mine detonation, offshore oil and gas and windfarm infrastructure inspection, hull and pier inspection, aquatic research, and maritime.

VideoRay tethered underwater ROVs can be deployed for 24/7/365 operation at depths down to 305 metres (2,000m in float mode), with power supplied from the host platform or vessel. Also in development is a battery operated ROV that can sustain underwater operational up-time for up to eight hours, and allows for a slimmer, lighter tether devoted purely for video and communications transmission.

Adapting to any mission

Among its many innovations, VideoRay offers an interchangeable, modular component ROV system residing on a single intelligent network. The system provides an extremely flexible and customisable platform that can be easily adapted to specific missions, markets and payloads.

VideoRay ROVs are designed to handle missions with size, weight, and deployment speed constraints. They are also distinguished by powerful thrust, longer tether lengths, higher resolution video and interchangeable, modular systems.

Securing waterways and high traffic ports

VideoRay Defender systems have been carefully optimised to meet the exacting specifications of the US Navy explosive ordnance disposal (EOD) programme, whose mission is to help secure US waterways using ROVs to identify and neutralise underwater improvised explosive devices. Code-named the Blowfish Project, the ROVs require advanced integrated controls on the vehicles, allowing precision operations and multifunction manipulator arms calibrated to specific payloads.

As part of the EOD programme, the VideoRay Defender systems will be configured by the Navy for defence and security operations including very shallow water, littoral mine countermeasures, port security missions and hull and pier inspection.

From mine countermeasures and underwater search and rescue to port security and  surveillance, VideoRay ROVs are helping  reduce risk and achieve results faster and easier

Above: From mine countermeasures and underwater search and rescue to port security and surveillance, VideoRay ROVs are helping reduce risk and achieve results faster and easier

“The system will provide separation between EOD operators and underwater explosive threat hazards, while they mitigate the effects of those threats, without causing collateral damage to surrounding vessels and infrastructure,” said US Navy Lt. Cmdr. Michael Bailey, Programme Integrator for the Counter Improvised Threat Technologies Department. “Progress has enabled components of the Blowfish system to be integrated into a new ROV - the VideoRay Defender - which is destined to be part of a family of US Navy EOD response vehicles.”

Scaling for payloads and mission-specific protocols

To achieve advanced ROV capabilities, VideoRay requires a sophisticated power delivery network architecture that allows them to design ever-smaller ROVs with more power and greater manoeuvrability at greater depths. Among the many design factors at play is the modularity and power density of the onboard power components, the key to enabling the VideoRay scalable ROV portfolio of providing the flexibility to swap high performance modules to accommodate evolving requirements with the added agility to quickly and easily customise ROVs for customers.

The portfolio of Vicor DC/DC power conversion modules are well suited for the VideoRay design ethos, playing a pivotal role in the development path for current and future-generation ROVs. Leveraging a wide range of Vicor components, VideoRay relies on Vicor to meet exacting requirements for power density, efficiency and low EMI noise in a manner that reduces the need for bulky heat sinking systems and additional filtering. This enables a sleek, power-dense system design that allows for efficient cooling while preserving valuable board space for other value-add componentry.

High performance power for rugged missions

The high-efficiency, fixed-ratio Vicor BCM bus converter used in the VideoRay Pro 4 Main Controller uses high-voltage BCM modules in the top side power converters to help generate the tether voltage, with advanced heat sinking and active cooling for easy thermal management in a waterproof enclosure.

BCMs use the Vicor proprietary SAC (Sine Amplitude Converter) topology, an extremely efficient resonant-tank based DC/DC converter architecture, to accomplish bidirectional fixed-ratio DC/DC conversion. With input voltage ranges from 36 to 800V and transforming voltage by various K factors to support a wide range of applications, some BCMs also feature integrated PMBus telemetry, control and EMI filtering. BCMs can reach peak efficiencies of 98% with achieve power densities up to 2,400W/in³ and can have their inputs in parallel into high-power arrays and outputs connected in series and/or parallel to achieve even higher output voltages and/or currents than a single module.

Diminutive size and weight support precision manoeuvrability

One potential limitation to achieving greater underwater depth is the bulk of the high voltage tether. VideoRay was able to overcome this limitation by designing a thinner tether employing higher voltages that reduce power loss along the cable, akin to high voltage transmission lines. To do this, VideoRay employed Vicor DCM high voltage DC/DC converters.

These high density power modules provide a robust, compact, efficient and scalable solution to convert the high voltage power source to a low bus voltage to power the thrusters and onboard electronics at up to a few kilowatts. This power is necessary for the ROV to maintain a stable, stationary position in high water currents up to three or four knots. The high and wide input range of the converters is also important to allow for voltage droop along the very long, very thin tether.

VideoRay's family of underwater ROVs (remotely  operated vehicles) can be deployed on  specialising missions quickly because of their proprietary modular design system.  Different missions require modifications in size, weight, payload and power, which can be easily  accommodated, while still delivering top performance

Above: VideoRay's family of underwater ROVs (remotely operated vehicles) can be deployed on specialising missions quickly because of their proprietary modular design system. Different missions require modifications in size, weight, payload and power, which can be easily accommodated, while still delivering top performance

For battery powered ROVs, VideoRay is using the Vicor high power, high density, 97% efficient PRM buck-boost converters with constant-current and constant-voltage control for battery management. Featuring a zero-voltage switching (ZVS) architecture, PRM buck-boost regulators accommodate a wide input voltage range and provide a regulated, adjustable output voltage. PRMs can be used stand alone as non-isolated voltage regulators or combined with VTM current multipliers for an isolated or non-isolated DC/DC factorised power solution.

VideoRay is leveraging Vicor power components across its growing ROV portfolio in a manner that easily scales to meet evolving needs. Working together, VideoRay and Vicor have innovated a modular, high-density power delivery network architecture that enables VideoRay to develop smaller yet more powerful ROVs capable of operating continuously at great depths, with 24/7 run-time.

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