Kalman HydroBall

Hydrodynamic ball with Kalman filtering capabilities.

Collaboration diagram for Kalman HydroBall:

KalmanHydroBall inherits from both HydroBall and KalmanObject, so that it is applicable for Kalman filtering. It has all the setup HydroBall has, with additional inputs and parameters defined below.

Author

Joakim Haugen

Example configuration excerpt

<Lib
  LibName    = "fhsim_base"
  SimObject  = "Kalman/Example/HydroBall"
  Name       = "Ball"
  Radius     = "1"
  Density    = "2000"
 
  MeasurementNoise     = "1"
  PositionUncertainty  = "5e-4"
  VelocityUncertainty  = "1e-6"
  InitialDiagP         = "1e-3,1e-3,1e-3,1e-4,1e-4,1e-4"
/>
<Connection
  Ball.ExternForce = "Cable.ForceB"
  Ball.Current     = "Current.State"
/>
<Connection
  Ball.MeasuredPosition = "0,0,18.8"
/>
<InitialCondition
  Ball.Position = "0,19,0"
  Ball.Velocity = "0,0,0"
/>

Input Ports

Name	Width	Description
ExternForce	3	External forces acting on the ball, e.g. from other SimObjects.
Current	3	The uniform current of the surrounding water.
MeasuredPosition	3	The measurement of its position.

Output Ports

Name	Width	Description
Position	3	The position of the centroid of the ball.
Velocity	3	The linear velocity of the ball.

Configuration parameters

Name	Width	Description
Radius	1	Radius of the ball [meter].
Density	1	Density of the ball [kg/m^3].
MeasurementNoise	1	Noise variance for the position measurement [m^2].
PositionUncertainty	1	Variance of the position [m^2].
VelocityUncertainty	1	Variance of the velocity [(m/s)^2].
InitialDiagP	6	Estimation error variance at initial time [diag([m^2, m^2, m^2], (m/s)^2, (m/s)^2, (m/s)^2])].

Initial conditions

Name	Width	Description
Position	3	-.
Velocity	3	-.

Full example file

<Contents>
  <OBJECTS>
    <Lib
      LibName = "fhsim_base"
      SimObject = "Kalman/ZeroDynamics"
      Name = "Current"
      Dimension = "3"
      P0 = "5e-2,5e-2,1e-4"
      Q = "1e-4,1e-4,1e-5"
    />
    <Lib
      LibName = "fhsim_base"
      SimObject = "Kalman/Example/HydroBall"
      Name = "Ball"
      Radius = "1.0"
      Density = "1100"
 
      MeasurementNoise    = "1"
      PositionUncertainty  = "5e-4"
      VelocityUncertainty  = "1e-6"
      InitialDiagP         = "1e-3,1e-3,1e-3,1e-3,1e-3,1e-3"
    />
    <Lib
      LibName = "fhsim_base"
      SimObject = "Kalman/Example/HydroCable"
      Name = "Cable"
      Diameter = "0.02"
      Density = "2000"
      Modulus = "20"
      Length = "20"
      InternalPoints = "2"
 
      ElementPositionUncertainty   = "5e-4"
      ElementVelocityUncertainty   = "1e-6"
      ElementInitialDiagP     = "1e-3,1e-3,1e-3,1e-3,1e-3,1e-3"
    />
  </OBJECTS>
 
  <INTERCONNECTIONS>
 
    <Connection
      Ball.ExternForce = "Cable.ForceB"
      Ball.Current     = "Current.State"
    />
 
    <Connection
      Cable.PositionA = "0,0,0"
      Cable.PositionB = "Ball.Position"
      Cable.VelocityA = "0,0,0"
      Cable.VelocityB = "Ball.Velocity"
      Cable.Current   = "Current.State"
    />
 
    <Connection
      Ball.MeasuredPosition = "0,0,18.8"
    />
  </INTERCONNECTIONS>
 
  <INITIALIZATION>
    <InitialCondition
    Ball.Position = "0,19,0"
    Ball.Velocity = "0,0,0"
    Current.State = "0,0,0"
    />
  </INITIALIZATION>
 
  <INTEGRATION>
    <Engine
    IntegratorMethod="0"
    NumCores="1"
    TOutput="0, 0:1e-1:Inf, 150"
    stepsize ="2e-4"
    HMin="0.5"
    FileOutput="objects:ports"
  />
 
  </INTEGRATION>
</Contents>

This SimObject is referred to as Kalman/Example/HydroBall