6-DOF trawl door

Simulation of a trawl door in six degrees of freedom.

Collaboration diagram for 6-DOF trawl door:

Author

Karl-Johan Reite

Date

21.04.2008 KJR: Initial version.

Simulation of a trawl door in six degrees of freedom. This model includes a fairly complex model of the hydrodynamic forces and the fastening points of the warp and the bridles. It is also based on unit quaternions for translation between different coordinate systems, to avoid the singularity problem of Euler angles.

Todo:

Fix missing resource "traaldoer", and change Mesh in example file. Also make a more complete example file.

Complete documentation (What is Force1, Force2 and Force3?).

Note

Unlike many other simObjects, the parameter Mesh does not take the extension .mesh. The parameter must therefore be set as e.g. "fhSphere" instead of "fhSphere.mesh"

For the time being, the parameter Mesh needs to b set as "fhSpere", in the input file. The trawldoor will be visualized as a white elliptical sphere.

Example configuration excerpt

<Lib LibName                 = "fishery"
   SimObject                 = "Trawl/TrawlDoor"
   Name                      = "Door"
   Mass                      = "3400"
   Area                      = "8"
   AR                        = "3"
   MaxLiftCoeff              = "1.6"
   DragCoeffAtMaxLift        = "0.5"
   IsPort                    = "1"
   WarpPos                   = "0.25, -0.3, -0.2"
   LBPos                     = "-1.5, 0.3,  2.0"
   UBPos                     = "-1.5, 0.3, -2.0"
   COG                       = "0, 0, 0.7"
   Mesh                      = "fhSphere"
   Curvature                 = "3.0"
   VisualizationScale        = "1"
/>

Todo:

Add config details

Input Ports

Name	Width	Description
Force1	3	Description here.
Force2	3	Description here.
Force3	3	Description here.

Output Ports

Name	Width	Description
Pos1	3	Position.
Pos2	3	Position.
Pos3	3	Position.
Vel1	3	Velocity.
Vel2	3	Velocity.
Vel3	3	Velocity.

Configuration parameters

Name	Width	Description
Mass	1	Mass of trawl door.
Density	1	Density of trawl door (Default: 7900).
Area	1	Area of trawl door.
Curvature	1	Description here.
IsPort	1	Description here.
Rho	1	Density of sea water (Default: 1025).
AR	1	Description here (Default: 1.4).
MaxLiftCoeff	1	Description here (Default: 1.9).
DragCoeffAtMaxLift	1	Description here (Default: 0.84).
WarpPos	3	Description here.
LBPos	3	Description here.
UBPos	3	Description here.
COG	3	Description here.
VisualizationScale	1	Description here (Default: 1).
LengthScale	1	Description here.
BreadthScale	1	Description here.
CurvatureScale	1	Description here.
Mesh	1	Description here (Default: fhSphere.mesh).

Initial conditions

Name	Width	Description
Pos	3	Position (Default: "0,0,0").
Quater	4	Quaternion (Default: "1,0,0,0").
LocalVel	3	Local velocity (Default: "0,0,0").
Omega	3	Description here (Default: "0,0,0").

Full example file

<Contents>
   <OBJECTS>
      <Lib
         LibName                   = "base"
         SimObject                 = "Environment/Basic"
         Name                      = "Env"
         MeanDepth                 = "190"
         BottomRoughness           = "5"
         SurfaceTextureScale       = "1000"
         BottomTextureScale        = "15"
         BottomStructureScale      = "50"
         TerrainRadius             = "1000"
         SurfaceDepth              = "0"
         NumTerrainRings           = "170"
      />
      <Lib
         LibName                   = "fishery"
         SimObject                 = "Trawl/TrawlDoor"
         Name                      = "Door"
         Density                   = "7900"
         Mass                      = "3400"
         Area                      = "8"
         Curvature                 = "3.0"
         IsPort                    = "1"
         Rho                       = "1025"
         AR                        = "3"
         MaxLiftCoeff              = "1.6"
         DragCoeffAtMaxLift        = "0.5"
         WarpPos                   = "0.25, -0.3, -0.2"
         LBPos                     = "-1.5, 0.3,  2.0"
         UBPos                     = "-1.5, 0.3, -2.0"
         COG                       = "0, 0, 0.7"
         VisualizationScale        = "0.01"
         Mesh                      = "trawl_doors/traaldoer"
      />
   </OBJECTS>
 
   <INTERCONNECTIONS>
      <Connection
         Env.CurrentVel = "2.5,0,0"
         Door.Force1    = "0,0,0"
         Door.Force2    = "0,0,0"
         Door.Force3    = "0,0,0"
      />
   </INTERCONNECTIONS>
 
   <INITIALIZATION>
      <InitialCondition
         Door.Pos    = "0,0,20"
         Door.Quater = "0,0,0,1"
      />
   </INITIALIZATION>
 
   <INTEGRATION>
      <Engine
         IntegratorMethod           ="2"
         NumCores                   ="1"
         TOutput                    ="0, 1, 30"
         LogStates                  ="1"
         stepsize                   ="0"
         HMax                       ="0.002"
         HMin                       ="0.00000001"
         AbsTol                     ="1e-3"
         RelTol                     ="1e-3"
         UseRSSNormInsteadOfInfNorm ="0"
         FileOutput                 ="objects:all"
      />
   </INTEGRATION>
</Contents>

This SimObject is referred to as Trawl/TrawlDoor