1 tmr4225 marine operations, 2007.02.15 lecture content: –hydrodynamics of rovs – stealth 3000...

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TMR4225 Marine Operations, 2007.02.15

• Lecture content:– Hydrodynamics of ROVs – Stealth 3000

– Simulation as a tool for operational validation

– ROV pilot training

– Final comments on subsea vehicles

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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

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Flow characteristics for standard operations

• ROV– Non-streamlined body

– Mostly turbulent flow due to separation on edges

– Low speed

– Large angles of attack; have to be able to operate in cross current

– Different characteristics for up and down motion

– Complex flow due to interacting thrusters

– Umbilical drag can be high for operations at large depths

– Tether management system can be used to remove umbilical

induced motion of ROV

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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

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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

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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

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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

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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

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ROV operational challenges

• Surface vessel motion

• Crane tip motion

• Umbilical geometry and forces

• Operational foot-print

• ROV hydrodynamic characteristics– Influence of sea bottom

– Interference from subsea structures

• ROV control systems

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ROV operational phases

• Pre launch• Launching• Penetration of wave surface (splash zone)• Transit to work space• Entering work space, homing in on work task• Completing work task• Leaving work space• Transit to surface/Moving to next work space• Penetration of surface• Hook-up, lifting, securing on deck

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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

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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.

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Buzz group question no. 1:

• List functional requirements for a ROV simulator to be used for accessability studies

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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

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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)

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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)

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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

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New Marine ROV Simulator Launched

12/11/2006

Marine Simulation LLC announced the release of ROVsim, an affordable, physics accurate, and visually realistic Remotely Operated Vehicle (ROV) simulator. Using state of the art technologies originally developed for the video game industry and over 2 decades of hands-on industry experience, ROVsim is optimized to simulate a wide range of mission variables: from

changing currents and visibility, tether and collision problems, to electronics and gear failures. Potential simulated missions include: harbor security, hull inspections, dam and bridge inspections, deep water drilling and cable work,

law enforcement / evidence recovery, scientific data collection, tunnel / pipeline inspections, marine archeology and underwater rescue. ROVsim is

designed to operate on low-cost personal computers as well as “off the shelf” components and is available for both Microsoft Windows and Apple OS X

operating systems. A free demo version is available for download from Marine Simulation LLC's website www.marinesimulation.com/

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Downloads

Demo versions of vSHIP™ and ROVsim™ are available as free downloads. Select a link below for an automated form to contact us. Please complete this form, click on "submit" and we will reply by email within 24 hours with download instructions.

http://www.marinesimulation.com/downloads.html

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ROVSIM info

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Simulation benefits:

•Computer simulation of subsea operations has repeatedly proved itself, in the real world, as a means of driving up profit with the following direct benefits:

•Quickly generate visualisations of complex scenarios for training and marketing. •Repeatable and quantifiable training in a completely safe environment. •Early identification of design and implementation errors. •Simulator trained operators outperform other operators, both in speed and quality. •Users access powerful, physics-based simulation using our mature, in-house mathematics engine, that delivers ‘as real’ behaviour

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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

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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

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Oceaneering - ongoing work

• MIMIC– Modular Integrated Man-Machine Interaction and

Control

• VSIS– Virtual Subsea Intervention Solution

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””New” Concepts – ROV operationsNew” Concepts – ROV operations

AUV technology / AUV operationsAUV technology / AUV operations

WROV operationsWROV operations

FUTURE ROV OPERATIONS

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Work ROV operationsWork ROV operations

Optimisation of power efficiencyOptimisation of power efficiencyAbsolute requirement for deeper waterAbsolute requirement for deeper water

Fully electric systemsFully electric systems


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Work ROV operationsWork ROV operations

More efficient, Advanced intervention tasks More efficient, Advanced intervention tasks requires:requires:

Better vizualisationBetter vizualisation

Better planningBetter planning

Better reporting systemsBetter reporting systems

More trainingMore training

Access verificationsAccess verifications

Central controlCentral control


How can this be acheived?

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Advanced intervention tasksAdvanced intervention tasks3D Navigation tools3D Navigation tools

3D based planning tool3D based planning tool

Digital, visual ”online” reportingDigital, visual ”online” reporting

Realistic Simulator trainingRealistic Simulator training

Access verifications in Simulator during Access verifications in Simulator during engineering/planning of operationengineering/planning of operation

Central placed spesial control stationsCentral placed spesial control stations


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More efficient Work ROV operationsMore efficient Work ROV operations


MIMICMIMIC

Modular Integrated Man-machine Interaction and Control

+ VSISVSIS

Virtual Subsea Intervention Solution

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More efficient Work ROV operationsMore efficient Work ROV operations


MIMICMIMIC

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

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MIMICMIMIC

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MIMICMIMIC

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MIMICMIMIC

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MIMICMIMIC

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MIMICMIMIC

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MIMICMIMIC

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VSISVSISVirtual Subsea Intervention Solution

ROV training simulator. Central control room?

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MIMICMIMIC

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MIMIC TEST ONB SCARABEO#5

MIMICSensors

ROV System

3D ModelDatabase

Plan/ Report

Database

MIMIC / OST ROV simulator

STAVANGER/STJØRDAL SCARABEO 5

3D ModelDatabase

HiPaP

DGPS

Video

Mimic coord.

Telephone

ROV parametersEthern

et

Mimic – data flow chart

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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

1 tmr4225 marine operations, 2007.02.15 lecture content: –hydrodynamics of rovs – stealth 3000...

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