Simple Pendulum Model

Source Notebook

Model of a simple pendulum

Examples

Basic Examples (2) 

Retrieve the model:

In[1]:=
ResourceData[\!\(\*
TagBox["\"\<Simple Pendulum Model\>\"",
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\)]
Out[1]=

The icon:

In[2]:=
ResourceData[\!\(\*
TagBox["\"\<Simple Pendulum Model\>\"",
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\), "Icon"]
Out[2]=

Scope & Additional Elements (4) 

Available content elements:

In[3]:=
\!\(\*
TagBox[
RowBox[{"ResourceObject", "[", "\"\<Simple Pendulum Model\>\"", "]"}],
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\)["ContentElements"]
Out[3]=

The available model types:

In[4]:=
ResourceData[\!\(\*
TagBox["\"\<Simple Pendulum Model\>\"",
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\), "AvailableModelTypes"]
Out[4]=

The operating point:

In[5]:=
ResourceData[\!\(\*
TagBox["\"\<Simple Pendulum Model\>\"",
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\), "OperatingPoint"]
Out[5]=

The parameters:

In[6]:=
ResourceData[\!\(\*
TagBox["\"\<Simple Pendulum Model\>\"",
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\), "Parameters"]
Out[6]=

Analysis (3) 

The linear models about the two equilibrium positions for the set of parameter values:
In[7]:=
{ssm0, ssm180} = Table[ResourceData[\!\(\*
TagBox["\"\<Simple Pendulum Model\>\"",
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\), "StateSpaceModel"] /. {\[CapitalTheta] -> ang}, {ang, {0, \[Pi]}}] /. ResourceData[\!\(\*
TagBox["\"\<Simple Pendulum Model\>\"",
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\), "Parameters"]
Out[7]=
The response of the model linearized around 0 is stable, while the one around 180° is unstable:
In[8]:=
Grid[{Table[
   Plot[Evaluate@
     OutputResponse[{sys, {179 °, 0}}, {0}, {t, 0, 20}], {t, 0, 20}, PlotRange -> All], {sys, {ssm0, ssm180}}]}, Spacings -> 2]
Out[8]=

The affine model shows the pendulum reaching the stable equilibrium position from the unstable position:

In[9]:=
OutputResponse[{ResourceData[\!\(\*
TagBox["\"\<Simple Pendulum Model\>\"",
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\)] /. \[CapitalTheta] -> \[Pi] /. ResourceData[\!\(\*
TagBox["\"\<Simple Pendulum Model\>\"",
#& ,
BoxID -> "ResourceTag-Simple Pendulum Model-Input",
AutoDelete->True]\), "Parameters"], {179 °, 0}}, {0}, {t, 0, 20}];
Plot[%, {t, 0, 20}, PlotRange -> All]
Out[10]=

Suba Thomas, "Simple Pendulum Model" from the Wolfram Data Repository (2025)  

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