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/