3D Body

3DOF rigid body with gravity

Collaboration diagram for 3D Body:

Simulation of a rigid body in three degrees of freedom with gravity. Implemented in class C3DBody.

\begin{eqnarray*} \dot{\vec{x_1}} &=& \vec{x_2} \\ \dot{\vec{x_2}} &=& \frac{\sum \vec{F} + m\vec{g}}{m} \end{eqnarray*}

where

• \(\vec{x_1}\) is the position of the mass object
• \(\vec{x_2}\) is the velocity of the mass object
• \(\sum \vec{F}\) is the sum of the forces acting on the mass object
• \(\vec{g}\) is the gravitational acceleration vector
• \(m\) is the mass of the mass object

Author

Karl-Johan Reite

Date

01.01.2006 KJR: Initial version.

18.02.2011 KJR: Rewritten to new version of FhSim.

Example configuration excerpt

<Lib
  LibName      = "fhsim_base"
  SimObject    = "Ball/3DBody"
  Name         = "M"
/>
...
<Connection
  M.Force="0,0,0"
/>
...
<InitialCondition
  M.Pos="0,0,0"
  M.Vel="0,0,0"
/>

Input Ports

Name	Width	Description
Force	3	The total force acting on the mass, except gravity.

Output Ports

Name	Width	Description
Pos	3	Body position.
Vel	3	Body velocity.

Configuration parameters

Name	Width	Description
Mass	1	Mass of the object in kg.
Material	1	The visualization material of the mass, specified by its name.
Mesh	1	The visualization mesh (geometry) of the mass, specified by its filename. (Default: fhSphere.mesh)
Scale	1	Scaling of the mesh; defaults to 1 (Visualization).

Initial conditions

Name	Width	Description
Pos	3	3D position [m].
Vel	3	3D velocity [m/s].

Full example file

<Contents>
  <OBJECTS>
    
    <Lib
        LibName="base" 
        SimObject="Body/3DBody"  
        Name="M" 
        Scale="1"
        Mass="1"
        Material="Simple/Red"
    />
 
  </OBJECTS>
  
  <INTERCONNECTIONS>
    <Connection
    M.Force="0,0,0"
    />
  </INTERCONNECTIONS>
 
  <INITIALIZATION>
    <InitialCondition
    M.Pos="0,0,0"
    M.Vel="0,0,0"
    />
  </INITIALIZATION>
 
  <INTEGRATION>
    <Engine
    IntegratorMethod="2"
    NumCores="1"
    TOutput="0, 0:1:10, 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 Body/3DBody