6 DOF cable

Class containing a cable with six degrees of freedom.

Collaboration diagram for 6 DOF cable:

Author

Jørgen Haavind Jensen

Date

21.06.2011 JHJ: Initial version.

Todo:

Complete documentation of conf. params and check example file (coribo? Baumgarte?).

Example configuration excerpt

<Lib
  LibName            = "marine_elements"
  SimObject          = "RbCable/6DofCable"
  Name               = "C"
  Length             = "20"
  numElements        = "7"
  Alpha              = "1.0"
  Beta               = "1.0"
  Epsilon            = "0.0001"
  Weight             = "200"
  Radius             = "0.01"
  Damping_Tangential = "0.01"
  Damping_Normal     = "1.2"
/>

Input Ports

Name	Width	Description
posA	3	Position of end point A.
posB	3	Position of end point B.
velA	3	Velocity of end point A.
velB	3	Velocity of end point B.

Output Ports

Name	Width	Description
ForceA	3	The force acting on end point A.
ForceB	3	The force acting on end point B.

Configuration parameters

Name	Width	Description
Length	1	Length of cable
numElements	1	Number of internal mass elements.
Alpha	1	...
Beta	1	...
Epsilon	1	...
Weight	1	Weight of the cable.
Radius	1	Radius of the cable.
Damping_Tangential	1	Tangential damping coefficient.
Damping_Normal	1	Normal damping coefficient.

Initial conditions

Name	Width	Description
pos<i>	3	Position of point \(i \in {1\cdots\text{numElements}}\).
vel<i>	3	Velocity of point \(i \in {1\cdots\text{numElements}}\).
theta<i>	4	Orientation in quaternion of point \(i \in {1\cdots\text{numElements}}\)..
omega<i>	3	Angular velocity in rad per second of point \(i \in {1\cdots\text{numElements}}\)..

Full example file

<Contents>
   <OBJECTS>
      <Lib 
         LibName         = "base"
         SimObject       = "DefaultEnvironment"
         Name            = "Environment"
         Seadepth        = "500"
         Density         = "1000"
         CurrentVelocity = "1,0,0"
      />
 
      <Lib
         LibName            = "marine_elements"
         SimObject          = "RbCable/6DofCable"
         Name               = "C"
         Length             = "20"
         numElements        = "7"
         Alpha              = "1"
         Beta               = "1"
         Epsilon            = "1e-6"
         Weight             = "200"
         Radius             = "0.01"
         Damping_Tangential = "0.01"
         Damping_Normal     = "1.2"
      />
   </OBJECTS>
 
   <INTERCONNECTIONS>
      <Connection
         C.posA = "0,0,0"
         C.posB = "0,0.1,5.0"   
         C.velA = "0,0,0"
         C.velB = "0,0,0"
      />
   </INTERCONNECTIONS>
 
   <INITIALIZATION>
      <InitialCondition
      />
   </INITIALIZATION>
 
   <INTEGRATION>
      <Engine
         IntegratorMethod           = "2"
         NumCores                   = "1"
         TOutput                    = "0, 1, 10"
         LogStates                  = "0"
         Stepsize                   = "1e-4"
         HMax                       = "100"
         HMin                       = "1e-6"
         AbsTol                     = "1e-7"
         RelTol                     = "1e-7"
         UseRSSNormInsteadOfInfNorm = "0"
         FileOutput                 = "objects:states"
      />
   </INTEGRATION>
</Contents>