Page 641 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

642 CHAPTER 23 The Future of ROV Technology
Logic driven
Clearly, the future is logic-driven circuits. The tasks to be performed in such a circuit are any number of items such as turning valves, pulling and installing flying leads, inspecting assets for integrity, installing new nodes, and the like. The evolution will follow the development of shore- based controls in the following areas:
1. Placingthelogiccircuitsonto/intotheasset/nodeitself:Thispathfollowsthedevelopmentof shore-based controls changing the subsea wellhead from a valve panel or hydraulic control board to an intelligent control node. The wellhead will sense variations in pressures/temperatures along with gas/fluid phase, H2S contamination, hydrate formation, sand or water mix, and the like. Based on this sensory feedback, controls will be activated for manipulating valves and restrictions, thus inhibiting hydrate formation (assuring fluid flow), circling unwanted by-products back to the formation, and protecting infrastructure from damage at the wellhead or node.
2. Placing the logic circuit into the service vehicles: As the saying goes in the robotics industry, “Man in the loop is so yesterday.” The vehicle will communicate with the intelligent node (#1 above) to take over for operations that cannot be performed by the node itself. This involves further inspection or manipulation such as pulling leads, hot-stabbing chemicals/fluids, or other IRM and drill support tasks.
3. Development of messaging commands for assigning goal-oriented tasking to remote nodes and vehicles: To operate a full control system, a grand traffic cop must control the flow of the various nodes toward some higher logic, thus assuring the overall goals of the system are achieved (i.e., the entire field flows as designed). Such high-level commands typically do not tell the robot how to control itself but only to achieve a certain goal-oriented task such as “There is a decrease in flow on subsea processing facility A; therefore, Robot 23-5, execute subroutine 35B to inspect flowline 43A from Node 23 to Node 24 for flow of hydrocarbons.” The robot will awaken, undock, fly the requisite route, and then re-dock and report its findings to the central computer (and power down per its onboard logic). The central computer will use its findings to determine the next step in the flow assurance process.
Structurally compliant or free-traveling vehicles
This discussion focuses upon the vehicles within the system; therefore, the requirements of the
vehicles will depend upon the locomotive method:
1. Make the node switchable: As mentioned above, this method places the logic circuit on the specific asset. This does not require a vehicle in order to function, but will be able to communicate with the vehicle toward achieving a specific goal.
2. Structurally compliant vehicles: This method places the vehicle in semipermanent contact (much like a caterpillar or squirrel follows a branch) with the asset (e.g., a subsea oil riser), allowing the vehicle the ability to follow the assets without the excessive energy and navigational requirements of a free-traveling (i.e., autonomous) vehicle.
3. Bottom-crawlingvehicles:Thisvehiclecrawlsthebottomoneitherasubseatrack/railsystem(much like a railroad track between two terminals) or free-traveling via vehicle-mounted tracks/wheels.
4. Free-swimming vehicles: These vehicles are “free-flying,” neither attached to the structure nor to the bottom. These autonomous vehicles require a substantial amount of energy and logical processing for station-keeping, end-effecter manipulation, as well as navigation.