Transcript Ingen lysbildetittel

TMR4225 Marine Operations,
2007.02.15
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Hydrodynamics of ROVs – Stealth 3000
Simulation as a tool for operational validation
ROV pilot training
Final comments on subsea vehicles
ROV operational goals
• Visual inspection
– Inspection of underwater structures
– Observation of ongoing work tasks on subsea structures
– Biological observation
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Different types of mechanical inspection
Non destructive testing
Mechanical work
Biological sampling, water column and bottom
Flow characteristics for standard
operations
• ROV
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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
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 portstarboard symmetry
• See section 4.6 of lecture note for ROV motion equation
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Other forces
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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:
– Breadth:
– Depth:
3.2 m
1.9 m
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
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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
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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
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-HardwareHuman-in-the-Loop)
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Simulator design (cont.)
• Check
– http://www.marinecybernetics.com
– for their modular simulator concept
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– 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
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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/
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:
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•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
Necessary improvements for advanced
ROV operations
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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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FUTURE ROV OPERATIONS
”New” Concepts – ROV operations
 AUV technology / AUV operations
 WROV operations
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FUTURE ROV OPERATIONS
Work ROV operations
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Optimisation of power efficiency
Absolute requirement for deeper water
Fully electric systems
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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
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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
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FUTURE ROV OPERATIONS
More efficient Work ROV operations
 MIMIC
Modular Integrated Man-machine Interaction and
Control
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 VSIS
Virtual Subsea Intervention Solution
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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
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FUTURE ROV OPERATIONS
MIMIC
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FUTURE ROV OPERATIONS
MIMIC
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FUTURE ROV OPERATIONS
MIMIC
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FUTURE ROV OPERATIONS
MIMIC
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FUTURE ROV OPERATIONS
MIMIC
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FUTURE ROV OPERATIONS
MIMIC
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FUTURE ROV OPERATIONS
VSIS
Virtual Subsea Intervention Solution
ROV training
Central control
room? simulator.
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FUTURE ROV OPERATIONS
MIMIC
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MIMIC TEST ONB SCARABEO#5
Mimic – data flow chart
STAVANGER/STJØRDAL
SCARABEO 5
Telephone
MIMIC /
OST ROV
simulator
Sensors
MIMIC
DGPS
ROV System
3D Model
Database
3D Model
Database
Ethernet
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HiPaP
Plan/
Report
Database
ROV parameters
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
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