Structure of underwater intervention manipulators in workspace constraint environment and architecture of their control system

To develop underwater intervention tools, it is necessary to start with the customer (e.g. oil company) needs. Tasks and capabilities form a 2D matrix. ROV subsystems provide a third dimension. The article discusses this third dimension of the reference framework, at the subsystem level, but focusses mainly on the manipulator subsystem and its control subsystem aiming at exploring problems of: What kind of manipulator structure is suitable for underwater-unmanned intervention in a limited workspace environment? What kind of control architecture for manipulator control is suitable for underwater unmanned manipulation? These questions are important to address because we expect to see more deepwater projects to arise with water depths that exclude the use of human divers. Under these circumstances we need flexible equipment to be able to perform work tasks which is not well known or defined in beforehand, and as well there is a need to perform tasks that are well defined but difficult to achieve (like path following operations which include both control of speed and position accuracy).