3D Mass

3DOF point mass without gravity

Collaboration diagram for 3D Mass:

Simulation of a mass point in three degrees of freedom without gravity. Implemented in class CMass.

\begin{eqnarray*} \dot{\vec{x_1}} &=& \vec{x_2} \\ \dot{\vec{x_2}} &=& \frac{\sum \vec{F}}{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
• \(m\) 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    = "Body/Mass"
  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, including gravity.

Output Ports

Name	Width	Description
Pos	3	Mass position.
Vel	3	Mass 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/Mass"  
        Name="M" 
        Scale="1"
        Mass="1"
        Material="Simple/Red"
    />
    
    
  </OBJECTS>
  
  <INTERCONNECTIONS>
    <Connection
        M.Force="10,0,0"
    />
  </INTERCONNECTIONS>
        
  <INITIALIZATION>
    <InitialCondition
        M.Pos="0,0,0"
        M.Vel="0,0,0"
    />
  </INITIALIZATION>
 
  <SIMULATION>
    <Timing TStart="0" TEnd="11.0"/>
    <Integrator Method="RK45_i" NumCores="1" LogStates="1" UseRSSNorm="0">
      <StepControl Step="0.001" StepMax="0.002" StepMin="0.00000001" AbsTol="1e-3" RelTol="1e-3"/>
    </Integrator>
  </SIMULATION>
  <OBSERVERS>
    <FileOutput TOutput="0, 1:1:10, 60 " Select="objects:all"/>
  </OBSERVERS>
</Contents>

This SimObject is referred to as Body/Mass