Visualisation and simulation are distinct technologies with different but complementary applications. Visualisation ranges from a simple graphic of a field to a complex graphic model in which objects can be moved around relative to each other by an operator, and can be imaged in both 2D and 3D. Visualisations can show live data input, so GPS and USBL inputs give the position of a support vessel and its ROV or a pipelay barge and its anchor lines making it possible for operations such as tracking an ROV's manoeuvres near a subsea template or monitoring touchdown during cable or pipeline deployment to be shown in realtime.
Simulation, on the other hand, rather than just showing inputs, incorporates a physics engine so objects move in response to their environment, in complex water currents and swell for instance, and may also include user interactive inputs in parallel. An ROV trainer simulates the subsea environment that pilots must fly through and presents complex situations where the pilot's decisions directly affect the outcome.
General Robotics' ROVolution simulator reproduces the ‘actual' subsea conditions that an ROV pilot must deal with. A key aspect is the hydrodynamic modelling of objects in the water, so that the simulator responds to the controls just like its real counterpart, with behaviour based on real physical properties: mass, density, drag, including currents and ROV speed, sonar input, and the forces acting on the tether and the ROV. Different visibility conditions can also be simulated, with varying light levels, water fogging and suspended particles.
ROVolution uses standard PCs running Windows XP for ROV pilot training, manipulator operator training, subsea task planning, and access simulation. ROVolution is available as an off-the-shelf product for basic training of ROV pilots, typically set up to simulate an industry-standard Triton ROV with Titan and RigMaster manipulators. For more advanced training on specific ROVs, GRL can integrate ROVolution to work with a range of control consoles to precisely simulate a wide range of ROVs.
Norwegian subsea intervention specialist DeepOcean uses ROVolution to train pilots for its KystDesign Installer and Supporter ROVs, working from vessels and offshore platforms in the North Sea and the Mediterranean.
DeepOcean initially relied on recruiting experienced ROV pilots and then crosstraining them on the Installers offshore, but this became too slow and expensive. GRL was commissioned to adapt its generic ROVolution simulator for the Installer ROVs.Working with KystDesign and DeepOcean, GRL took the command signals from the Installer control console and linked them to the ROVolution simulator so trainees could sit at their usual control console and operate standard controls. At the same time, the simulator feeds back the ROV waterdepth, altitude and attitude into the pilot's console, with simulated views through the ROV's cameras, so they feel as though they are flying an actual Installer in the field.
It takes a new pilot, with no prior ROV experience, around two years of training to gain DeepOcean's certificate of competence. Typically, the cost of operating a ROV support vessel is over £3000/h. Using the ROVolution simulator, trainees notch up the hours far more quickly and less expensively than using the Installers offshore - not always the best place to test novice pilots.
DeepOcean plans to extend its use of ROVolution to learning new tasks and scenarios, particularly job simulations, so pilots are familiar with the work to be done before they go offshore.
Late last year, General Robotics won an order from Sonsub for a second ROVolution simulator for use in training pilottechnicians specifically for the Italian subsea contractor's own Innovator ROVs. The simulator has been installed at Sonsub's new advanced training centre in Aberdeen, and integration with an Innovator console is to be completed by March.
There is currently a clear trend that sees visualisation and simulation tools being increasingly used in ROV and other offshore operations, for both task planning and crew training. In the future, engineering tools and planning tools are likely to continue to converge, so not only will the deployment of equipment to the seabed be visualised taking in live inputs, but control and simulation will come together to allow the operator to respond to events and drive what happens in the real world.
Such developments promise huge benefits not just in improved training and reduced operation timescales but in greater operational predictability and reliability, leading in turn to improved safety, lower costs and lower environmental impact in all offshore tasks.
by Jason Tisdall
About the author
Jason Tisdall moved up to the post of managing director of General Robotics in 2006, following a two-year stint as the Milton Keynes, UK-based company's director of business development. He was awarded a PhD by University College, London, for his thesis on force control of subsea manipulators.
© 2007 Offshore Engineer