Lecture no. 4, 2005.05.09 ROV characteristics ROV types/classes Work tasks for ROVs Some work ROVs NTNU’s Minerva vehicle ROV simulators for engineering studies ROV simulators for operator training Review of underwater vehicle topics

ROV overview ROV: Remotely Operated Vehicle with umbilical connection to mother vessel Umbilical is used for power transfer to the vehicle and for communication between it and its pilot

ROV types/classes A common classification is: Low cost observation ROV (electric) Small observation ROV (electric) Large observation/light work ROV (electric) Ultra-deep observation/sampling ROV (electric) Medium light/medium work ROV (electro/hydraulic) Large heavy work/large payload ROV (electro/hydraulic) Ultra-deep heavy work/large payload ROV (electro/hydraulic)

Examples of ROVs Check organisational web sites http://www.rov.org http://www.rov.net http://www.rovworld.com http://www.diveweb.com/rovs/features/uv-wi99.01.htm Check suppliers and operators websites: http://www.kystdesign.no http://www.sperre-as.com http://www.oceaneering.com http://www.stoltoffshore.com

NTNU ROV Minerva NTNU has bought an ROV for biological research 2 Dr. ing studies have been allocated to develop tools and procedures for scientific use of the ROV For more info see the web site: http://www.ivt.ntnu.no/imt/minerva

Minerva ROV

ROV operational goals Visual inspection Inspection of underwater structures Observation of ongoing work tasks on subsea structures Biological observation Different types of mechanical inspection Non destructive testing Mechanical work Biological sampling, water column and bottom

Equation of motion for ROVs 6 degree of freedom (6DOF) model No defined steady state motion as a baseline for development of motion equations ROVs are usually asymmetrical up-down and fore-aft As far as possible the ROVs are designed for port-starboard symmetry See section 4.6 of lecture note for ROV motion equation

Hydrodynamic added mass/moment of inertia 6 x 6 matrix Non-diagonal terms exists Terms may have different values for positive and negative accelerations, especially for heave and pitch motion Ideal fluid sink-source methods can be used Motion decay tests can be used to find some terms Generalized Planar Motion Mechanism tests can be used to find all terms Simplified 2D crossections can be used to estimate some of the terms

Velocity dependent forces (drag and lift) Non linear terms are important Streamlining of bouyancy elements influence both drag and lift forces and moments Motion decay tests can be used to find some drag terms Generalized Planar Motion Mechanism tests can be used to find all terms

ROV umbilicals Vessel motion and indusced motion at the upper end of the umbilical Umbilical geometry resulting from depth varying current Use of buoyancy 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 Exercise no. 6 includes comparison of own calculations with model test results for MINERVA

Minerva 1:5 scale model test

Minerva 1:5 scale model test

Other forces Gravity and buoyancy forces and moments Thruster forces and moments Control forces from any additional control units Umbilical forces Environmental forces Interaction forces from bottom and/or sea bed structures

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 (Activity not included in lecture)

Student responses 2004 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), 2004: 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

FUTURE ROV OPERATIONS ”New” Concepts – ROV operations AUV technology / AUV operations WROV operations

FUTURE ROV OPERATIONS Work ROV operations Optimisation of power efficiency Absolute requirement for deeper water Fully electric systems

FUTURE ROV OPERATIONS Work ROV operations More efficient, Advanced intervention tasks requires: Better vizualisation Better planning Better reporting systems More training Access verifications Central control How can this be acheived?

FUTURE ROV OPERATIONS Advanced intervention tasks 3D Navigation tools 3D based planning tool Digital, visual ”online” reporting Realistic Simulator training Access verifications in Simulator during engineering/planning of operation Central placed spesial control stations

FUTURE ROV OPERATIONS More efficient Work ROV operations MIMIC VSIS + Modular Integrated Man-machine Interaction and Control + VSIS Virtual Subsea Intervention Solution

FUTURE ROV OPERATIONS More efficient Work ROV operations MIMIC Realtime 3D positioning system for ROV operations Built in, activity work plan Generate work-status reports Easy to construct and edit activity work plans View active task functions

FUTURE ROV OPERATIONS MIMIC

FUTURE ROV OPERATIONS MIMIC

FUTURE ROV OPERATIONS MIMIC

FUTURE ROV OPERATIONS MIMIC

FUTURE ROV OPERATIONS MIMIC

FUTURE ROV OPERATIONS MIMIC

FUTURE ROV OPERATIONS VSIS Virtual Subsea Intervention Solution ROV training simulator. Central control room?

FUTURE ROV OPERATIONS MIMIC

MIMIC / OST ROV simulator MIMIC TEST ONB SCARABEO#5 Mimic – data flow chart STAVANGER/STJØRDAL SCARABEO 5 Telephone HiPaP MIMIC / OST ROV simulator MIMIC Sensors DGPS ROV System 3D Model Database 3D Model Database Plan/ Report Database ROV parameters Ethernet Video Mimic coord.

Summary ROV Observation platform to support topside operators performing complex subsea work tasks Workhorse for installation and maintenance tasks Tether management system is a must for ”workhorse” ROVs ROV simulators are important for studies of accessability on subsea structures (engineering simulator) ROV simulators are used for ROV pilot training