Virtual Environment for Ships and Ship-Mounted Cranes
Ali H. Nayfeh
Lance Arsenault, Dean Mook, and Ron KrizVirginia Polytechnic Institute
and State University
DURIP
Supported by the Office of Naval Research
Dr. Kam Ng, Technical Monitor
MURI on Nonlinear Active Control of Dynamical Systems
Supported by the
Office of Naval Research
Dr. Kam Ng
Technical Monitor
Objectives of the MURI
Develop a unified control methodology and control strategy for nonlinear dynamical systems and processes
• Develop controller architecture and control algorithms for both high- and low-level controls for undersea vehicles, shipboard crane operation, and large-scale power electronic systems
• Develop simulations of ship hydrodynamics and control methodologies that can be used to conceptualize advanced hull forms
Concentration Areas
Control Methodology & Controller Architecture
Control Algorithms
Unmanned UnderseaVehicles (UUV)
Shipboard Crane Operation
Power Electronics Building Blocks
(PEBB)
Ship Motion PredictionSimulation & Control
Simulator Objectives
• State-of-the-art physical models are used to develop a state-of- the-art Ship and Crane Simulator Testbed at the Virginia Tech CAVE
• Testbed serves as a platform for testing ship and crane technologies
• Testbed can be used to test the boresight of sensors and data-link margins
Virginia Tech CAVE
• Visual image generation system with three pipes– Image generation computer
– Head motion tracking system
• Image display system– Four high-resolution projectors
– Three projection walls and one projection floor
– Liquid crystal eyes stereoscopic system
• Sound simulation system• Six-degree-of-freedom motion base
CAVE Capability
• Computer-generated multi-sensory information is rear projected in stereo onto the walls and floor of the CAVE and viewed with stereo glasses
• Head motion tracking system allows the viewer to walk around the system
• The viewer could see what amounts to an action theatre of one or more ships– The theatre extends beyond the walls of the CAVE
• The viewer experiences all design variables in concert
• Engineers can create and evaluate system prototypes
Simulator Characteristics
• Moving platform– Simulates the motion of a ship
– Permits a virtual movement about and inspection of the ship and experiencing its motion in high sea states
• Crane operator functions in a highly realistic virtual environment complete with– High-fidelity 270 degree scene visualization
– Ambient sound
– Base motion
– Physical control console
– Chair and cupola
Visualization of Ship Motion and Control
• Large-amplitude (nonlinear) ship motion• Simulations of ship hydrodynamics• Motion control systems
– Anti-roll tanks– Anti-roll weights– Hull-mounted fins– Hull-mounted cavitating spoilers– Hybrid designs with rudder action and course
keeping• Evaluation of different hull designs
Destroyer Model in a Regular Head Sea-Only Pitch Motion is Directly Excited
Cargo Transfer at Sea
3D Uncontrolled Response• Animation
is faster than real time.
• 2° Roll at n.
• 1° Pitch at n.
• 1 ft Heave at 2n.
3D Controlled Response• Animation
is faster than real time.
• 2° Roll at n.
• 1° Pitch at n.
• 1 ft Heave at 2n.
3D Controlled ResponseSlew Maneuver• Animation
is faster than real time.
• 2° Roll at n.
• 1° Pitch at n.
• 1 ft Heave at 2n.
Experimental Demonstration
• Built 3-DOF Ship Motion Simulation Platform– General Pitch, Roll, and
Heave capability
– Sinusoidal excitations in present results
• Equipped 1/24th scale model of T-ACS crane (NSWC) with motor and cable
• Crane control executed on PC
Uncontrolled Response
• 1° Roll at n.
• 0.5° Pitch at n.
• 0.5 in Heave at 2n.
Controlled Response
• 1° Roll at n.
• 0.5° Pitch at n.
• 0.5 in Heave at 2n.
Controlled Response
• 2° Roll at n.
• 1° Pitch at n.
• 0.5 in Heave at 2n.
Controlled ResponseSlew Maneuver
• 1° Roll at n.
• 0.5° Pitch at n.
• 0.5 in Heave at 2n.
Controlled ResponseSlew Maneuver
• 2° Roll at n.
• 1° Pitch at n.
• 0.5 in Heave at 2n.
Motion Base
DTK Servermemory manager
SharedMemorysystem state
Motion Basecom motion base
Motion Basecontroller
command
base state
LAMPship dynamics
ship
Fun Filtermotion filter
motion
graphics Render
draw visual
Crane Modelcrane dynamics
crane
Crane Controloperator filter
Operator Inputjoysticks/buttons
joysticks
buttons
sensors
MotionTrackernon-magnetic
head
wand
*complete
Soundsimulator driven
SharedMemorysystem state
command
base state
ship
motion
graphics
crane
joysticks
buttons
head
wand
VT CAVE
Desktop simulator of the VR Crane Ship
Simulator
GUIs
emulate real devices
Powered byDIVERSE
Progress
• CAVE running in new building
•With motion base•Or flat floor•Crane motion
Platform for Testing Technologies
• Response of (individual and multiple) ships in a dynamic sea environment
• Integrated ship-motion prediction and control• Determination of how different hull forms operate
in various sea states • Control of cargo handling aboard ships in high sea
states • Animation and visualization of ship and crane
systems in a dynamic sea environment• Virtual prototyping of ships and cranes, including
the input of operators• Ship- and crane-operator training• Collaborative environment
http://thor.sv.vt.edu/crane/