The 360° Freedom of Movement Concept

Background

Founding members of the Ocean Modules management team pioneered the 360° Freedom of Movement Concept for underwater vehicles 30 years ago. This concept lead to internationally renowned products such as the Sea-Owl, Sea-Eagle and Double Eagle vehicles that made SAAB Underwater Systems a leading ROV manufacturer.

In the years since, the technology has been implemented all over the globe, from the Royal Australian Navy’s Huon Class Mine Hunters to DeepOcean Norway’s brand-new fleet of Ocean Modules V8 range vehicles.

The V8 Sii is the third-generation 360° ROV. A unique control system allows unlimited rotation around any axis with maintained platform stability,. These features have been proven tremendously advantageous for tasks such as hull inspections, wreck documentation, underwater equipment repair, video and sonar recording and tool operation.

What makes it different?

Traditional ROV design places the buoyancy material at the top of the vehicle and ballast at the bottom, in order to create a stable platform.

This is an easy solution, but leads to a number of issues in real-world operational scenarios, where environmental forces, tether drag, limited maneuverability and limited ease of use all contribute to making operation difficult or even impossible under common conditions.

The Ocean Modules V8 range of vehicles are the only inspection class vehicles on the market placing the center of gravity and center of buoyancy in the middle of the vehicle, making it inherently unstable.

Stability is created artificially, using eight vectored thrusters, an advanced control system and feedback from precise sensors. This means that the vehicle can hold any position with unlimited pitch and roll indefinitely.

The capability to rotate 360 degrees in any dimension while maintaining platform stability allows an operator to conduct sonar and video inspections following the profile of sea floor, ship hull or subsea structure.

Intuitive Control

The choice of two operating modes, Horizon Relative and Body Relative, makes piloting even more intuitive. In the first, all movement is relative the surface, ideal for following surfaces such as the sea floor, a dam wall or a ship hull, regardless of the orientation of the vehicle. In the second, all movement is relative to the body of the vehicle, ideal for tracking a moving object with the camera, or using mounted tools, such as a manipulator.

Since the sonar, cameras, lights and mounted tools, such as a manipulator or sampler, are always aligned, there is no need for separate pan and tilt controls, reducing the cognitive stress on the operator, and thereby the risk of losing sight of the object being tracked.

Compact and Flexible

Joystick control does not translate directly to thruster movement, but is instead interpreted by the control system, for the most maneuverable and precise operation possible.

Another benefit of the V8 trademark maneuverability is the ability to obtain a correct sonar profile despite twists and turns, and of course the ability to enter tighter spaces.

Dynamic Automatic Adjustment of Heading, Pitch and Roll

The eight vectored thrusters allow equal thrust to be applied in any direction.

This greatly increases the vehicle's ability to maintain stability even when dealing with currents or significant tether drag, such as during extreme tunnel inspections, compared to a traditional ROV.

The V8 Sii has inspected pipes up to 1800 meters in length in the water system underneath Berlin, and performed inspections up to 2400 meters into nuclear power plant cooling water tunnels, without using any type of special tether management device.