TMR4225 Marine Operations, 2004.03.11 ROV systems: Umbilical Control system MINERVA drag characteristics STEALTH hydrodynamic characteristics ROV simulators Future challenges

ROV umbilicals Vessel motion and induced motion at upper end of umbilical Umbilical geometry resulting from depth varying current Use of buoyance and weight elements to obtain a S-form to reduce umbilical forces on the ROV Induced transverse vibrations of umbilical Forces and motions at lower end of umbilical

MINERVA tests Drag tests,varying speed Drag test, varying angle of attack Full scale tests Use of vehicle to generate input to parametric identification of mathematical model characteristics A possible project involving NTNU, Marine Cybernetics and Sperre? Exercise no.5 includes comparison of own calculations with model test results for MINERVA

STEALTH 3000 characteristics Dimensions Length: 3.2 m Breadth: 1.9 m Depth: 1.9 m 7 horizontal and 3 vertical thrusters Thruster pull and speed values: 1200kgf forward/aft, 5 knots forward, 3 knots reverse 500 kgf lateral, 2 knots lateral 1000 kgf vertical, 2.4 knots vertical

Hydrodynamic analysis of STEALTH MSc thesis on ”Manoeuvrability for ROV in a deep water tie-in operation” Simplified geometries used when estimating added mass coefficients based on work by Faltinsen and Øritsland for various shapes of rectangular bodies Quadratic damping coefficients used, corrections made for rounding of corners based on Hoerner curves Maximum speed as a function of heading angle has been calculated using simplified thruster model

ROV operational challenges Surface vessel motion Crane tip motion Umbilical geometry and forces ROV hydrodynamic characteristics Influence of sea bottom Interference from subsea structures ROV control systems

ROV simulator – systems requirements System requirements give DESIGN IMPLICATIONS with respect to: Simulation software Computer hardware architecture Mechanical packaging See article by Smallwood et. al. for more information A New Remotely Operated Underwater Vehicle for Dynamics and Control Research

System requirement - Example Simulate a variety of ROV design configurations for both military and commercial mission applications DESIGN IMPLICATIONS for simulation software: Sensor databases must include a wide range of underwater objects Modular model for ROV hydrodynamics Standard protocols for information exchange between modules DESIGN IMPLICATIONS for mechanical packaging System must be reconfigurable to replicate a wide range of control/operator console layouts.

Buzz group question no. 1: List functional requirements for a ROV simulator to be used for accessability studies Student responses: Easy integration of different kinds of underwater structures Easy implementation of different ROVs Easy implementation of different types of sensors Realistic model of umbilical Catalogue of error modes and related what –if statements Ability to simulate realistic environmental conditions, such as reduced visability and varying sonar conditions

Buzz group question no. 1 (cont): Realistic simulation of different navigation systems Obstacle recognition and handling Easy input interface for parametres related to ROV geometry, environment, navigation systems and different work tools Realistic model for calculation of ROV motion Good interface for presentation of ROV position and motion, including available control forces (Graphical User Interface, GUI)

Simulator design A modular design will make it easy to change modules for different subsystems of a ROV, subsea structures etc The simulator should allow both real time and fast time simulation High Level Architecture (HLA) is used for defence simulators to allow different modules to communicate through predefined protocols Marine Cybernetics uses: SH**2iL as their structure for simulators (Software-Hardware-Human-in-the-Loop)

Simulator design (cont.) Check http://www.marinecybernetics.com for their modular simulator concept or http://www.generalrobotics.co.uk/rovsimrecent.htm http://rovolution.co.uk/GRLMATIS.htm

Necessary improvements for advanced ROV operations 3D navigational tools 3D based planning tools Digital, visual ”online” reporting Realistic simulator training for pilots Access verification using simulator during the engineering phase of a subsea operation involving ROVs Central placed special control room

Challenges for future ROV operations Better visualization for pilot situational awareness Better planning of operations, for instance through use of simulator in the engineering design and development of operational procedures Better reporting system, including automatic functions to reduce the workload of the ROV pilot Closer co-operation between ROV pilot and subsea system experts in a central on shore operations control centre

Oceaneering - ongoing work MIMIC Modular Integrated Man-Machine Interaction and Control VSIS Virtual Subsea Intervention Solution