Dynamic Positioning Simulator - TU .Dynamic Positioning Simulator Dynamic Positioning Simulator Professional

  • View
    221

  • Download
    0

Embed Size (px)

Text of Dynamic Positioning Simulator - TU .Dynamic Positioning Simulator Dynamic Positioning Simulator...

  • Dynamic Positioning Simulator

    Dynamic Positioning SimulatorProfessional Training Tool

    Jalitha Wills

    TU Delft / VSTEP

    8 juni 2007

    Jalitha Wills Dynamic Positioning Simulator 1 / 24

  • Dynamic Positioning Simulator

    About VSTEP

    VSTEP: Virtual Safety Training & Education Platform;Locations: Rotterdam (headquarters), Oxford;Development teams in India, China and Eastern Europe;3 subjects: Scenario Training, Procedure Training and TrainingSimulator;Simulator game: Ship Simulator.

    Jalitha Wills Dynamic Positioning Simulator 2 / 24

  • Dynamic Positioning Simulator

    Outline

    1 Dynamic Positioning

    2 Hydrodynamics

    3 Modeling

    4 Future Goals

    Jalitha Wills Dynamic Positioning Simulator 3 / 24

  • Dynamic Positioning Simulator

    Dynamic Positioning

    Definitions

    A means of holding a vessel in relatively fixed positionwith respect to the ocean floor, without using anchorsaccomplished by two or more propulsive devicescontrolled by inputs from sonic instruments on the seabottom and on the vessel, by gyrocompass, by satellitenavigation or by other means.

    Jalitha Wills Dynamic Positioning Simulator 4 / 24

  • Dynamic Positioning Simulator

    Dynamic Positioning

    What is Dynamic Positioning?

    Different operational modes:

    manual/joystick mode

    auto-heading mode

    auto-position mode

    auto area position mode

    autopilot mode

    Jalitha Wills Dynamic Positioning Simulator 5 / 24

  • Dynamic Positioning Simulator

    Dynamic Positioning

    Why Dynamic Positioning?

    Advantages Dynamic Positioning:

    No tugboats needed;

    Offshore set-up is quick;

    Power saving;

    Precision situations more easily.

    Jalitha Wills Dynamic Positioning Simulator 6 / 24

  • Dynamic Positioning Simulator

    Dynamic Positioning

    Dynamic Positioning Training

    Test cases:

    Learn the system, joystick steering;

    Failure of the system;

    Erroneous input from sensors;

    Extreme weather situations.

    Jalitha Wills Dynamic Positioning Simulator 7 / 24

  • Dynamic Positioning Simulator

    Dynamic Positioning

    Mathematical Model behind Dynamic Positioning

    Jalitha Wills Dynamic Positioning Simulator 8 / 24

  • Dynamic Positioning Simulator

    Hydrodynamics

    Coordinate System

    Jalitha Wills Dynamic Positioning Simulator 9 / 24

  • Dynamic Positioning Simulator

    Hydrodynamics

    Forces on Ship: Current Force

    Fc =

    (12V

    2c CXc (c)ATS

    12V

    2c CYc (c)ALS

    )Mc =

    1

    2V 2c CMc (c)ALSL

    With: density of water, Vc current velocity, c current direction,ATS submerged transverse projected area, ALS submergedlongitudinal projected area, L length of ship, Cc(c) currentcoefficient.

    Jalitha Wills Dynamic Positioning Simulator 10 / 24

  • Dynamic Positioning Simulator

    Hydrodynamics

    Forces on Ship: Wind Force

    Fw =

    (12airV

    2rwCXw (rw )AT

    12airV

    2rwCYw (rw )AL

    )Mw =

    1

    2airV

    2rwCMw (rw )ALL

    With: air density of air, Vrw relative wind velocity, rw relativewind direction, AT transverse projected wind area, AL longitudinalprojected wind area, L length of ship, Cw (rw ) wind coefficient.

    Vw (z) = Vw (z = 10m) ( z

    10

    ) 18

    With: Vw (z = 10m) velocity at 10m.

    Jalitha Wills Dynamic Positioning Simulator 11 / 24

  • Dynamic Positioning Simulator

    Hydrodynamics

    Forces on Ship: Wave Force

    Fwd =

    (CXwd (wd , fwd)

    18gH

    21/3L

    CYwd (wd , fwd)18gH

    21/3L

    )Mwd = CMwd (wd , fwd)

    1

    8gH21/3L

    2

    With: density of water, wd wave direction, fwd regular wavefrequency, Cwd(wd , fwd) wave drift coefficient, g gravitycoefficient, H1/3 significant wave height and L length of ship.

    Jalitha Wills Dynamic Positioning Simulator 12 / 24

  • Dynamic Positioning Simulator

    Hydrodynamics

    Thrusters

    Jalitha Wills Dynamic Positioning Simulator 13 / 24

  • Dynamic Positioning Simulator

    Hydrodynamics

    Thruster Force

    Thrust : T = CTn2D4

    Torque : Q = CQn2D5

    With: density of water, n rpm, D diameter of propeller, CTthrust coefficient and CQ torque coefficient.

    Jalitha Wills Dynamic Positioning Simulator 14 / 24

  • Dynamic Positioning Simulator

    Modeling

    A First Model

    Limitations:

    Thruster force defined as x-force and y -force;

    No max thruster force;

    No moment for external force;

    No penalty for reverse thrust;

    Ship as pointmass;

    Only force calculation, no sailing yet;

    Inertia thrusters and ship.

    Jalitha Wills Dynamic Positioning Simulator 15 / 24

  • Dynamic Positioning Simulator

    Modeling

    Solution

    Algorithm - (1/3)

    1 Calculate necessary thruster forces:Force x-direction: Fx = Fxdemand Fxwind Fxcurrent FxwaveForce y -direction: Fy = Fydemand Fywind Fycurrent FywaveMoment: M = Mdemand Mwind Mcurrent Mwave

    2 Now it must hold:Fx =

    ni=1 (Fx)i

    Fy =n

    i=1 (Fy )iM =

    ni=1 (yi (Fx)i + xi (Fy )i )

    Jalitha Wills Dynamic Positioning Simulator 16 / 24

  • Dynamic Positioning Simulator

    Modeling

    Solution

    Algorithm - (1/3)

    1 Calculate necessary thruster forces:Force x-direction: Fx = Fxdemand Fxwind Fxcurrent FxwaveForce y -direction: Fy = Fydemand Fywind Fycurrent FywaveMoment: M = Mdemand Mwind Mcurrent Mwave

    2 Now it must hold:Fx =

    ni=1 (Fx)i

    Fy =n

    i=1 (Fy )iM =

    ni=1 (yi (Fx)i + xi (Fy )i )

    Jalitha Wills Dynamic Positioning Simulator 16 / 24

  • Dynamic Positioning Simulator

    Modeling

    Solution

    Algorithm - (2/3)

    3 Express Fxn and Fyn in other variables:(Fx)n = Fx

    n1i=1 (Fx)i

    (Fy )n = Fy n1

    i=1 (Fy )i

    4 With this and moment equation:

    (Fy )n1 =M+ynFxxnFy

    xn1xn +n1

    i=1

    (yiyn

    xn1xn (Fx)i)

    +n2i=1

    (xnxi

    xn1xn (Fy )i)

    Jalitha Wills Dynamic Positioning Simulator 17 / 24

  • Dynamic Positioning Simulator

    Modeling

    Solution

    Algorithm - (2/3)

    3 Express Fxn and Fyn in other variables:(Fx)n = Fx

    n1i=1 (Fx)i

    (Fy )n = Fy n1

    i=1 (Fy )i4 With this and moment equation:

    (Fy )n1 =M+ynFxxnFy

    xn1xn +n1

    i=1

    (yiyn

    xn1xn (Fx)i)

    +n2i=1

    (xnxi

    xn1xn (Fy )i)

    Jalitha Wills Dynamic Positioning Simulator 17 / 24

  • Dynamic Positioning Simulator

    Modeling

    Solution

    Algorithm - (3/3)

    5 Total power:g((Fx)1, . . . , (Fx)n1, (Fy )1, . . . , (Fy )n2) =n

    i=1

    (Fx)2i + (Fy )

    2i

    6 Minimize this total power with Method of Steepest Descentwith Linesearch.

    Jalitha Wills Dynamic Positioning Simulator 18 / 24

  • Dynamic Positioning Simulator

    Modeling

    Steepest Descent with Linesearch

    Searching for = opt s.t. f (xold f ) is minimal.

    Algorithm

    1 Start with min = 0 and max = 1.Calculate fi = f (x

    old if (xold)) with i = {min,max}.IF fmax > fmin: STOP.ELSE: min = max ; max = 2 max .fmin = fmax ; fmax = f (x

    old maxf (xold)).REPEAT.

    Now: min opt max .

    2 Find opt in the interval:

    IF ||min max || : STOP.ELSE: Split interval in two s.t. opt remains between min andmax .REPEAT.

    Jalitha Wills Dynamic Positioning Simulator 19 / 24

  • Dynamic Positioning Simulator

    Modeling

    Steepest Descent with Linesearch

    Searching for = opt s.t. f (xold f ) is minimal.

    Algorithm

    1 Start with min = 0 and max = 1.Calculate fi = f (x

    old if (xold)) with i = {min,max}.IF fmax > fmin: STOP.ELSE: min = max ; max = 2 max .fmin = fmax ; fmax = f (x

    old maxf (xold)).REPEAT.

    Now: min opt max .2 Find opt in the interval:

    IF ||min max || : STOP.ELSE: Split interval in two s.t. opt remains between min andmax .REPEAT.

    Jalitha Wills Dynamic Positioning Simulator 19 / 24

  • Dynamic Positioning Simulator

    Modeling

    Results

    Minimal power is: 58.7518; Positions: (-6,-50); (6,-50)Forces: (-4.1,-34.167); (-2.9,24.167)

    Jalitha Wills Dynamic Positioning Simulator 20 / 24

  • Dynamic Positioning Simulator

    Modeling

    Results

    Minimal power is: 12.3296; Positions: (-6,-50); (6,-50); (0,25)Forces: (-1,339,-3.325); (-1.16,-1.377); (-4.511,5.298)

    Jalitha Wills Dynamic Positioning Simulator 21 / 24

  • Dynamic Positioning Simulator

    Modeling

    Results

    Minimal power is: 12.2234

    Jalitha Wills Dynamic Positioning Simulator 22 / 24

  • Dynamic Positioning Simulator

    Future Goals

    Future Goals

    1 More realism;

    2 Transition Matlab C++;3 Sailing the ship;

    4 Test cases.

    Jalitha Wills Dynamic Positioning Simulator 23 / 24

  • Dynamic Positioning Simulator

    Questions?

    Questions?

    Jalitha Wills Dynamic Positioning Simulator 24 / 24

    Dynamic PositioningHydrodynamicsModelingFuture GoalsQuestions?