<!-- GENERATED by tools/generators/itemDocsEmitter.py from definitions/ - do not edit -->
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(sec-item-sensornode)=
# SensorNode

A sensor attached to a node, which measures one of the output variables of the node.

## Parameters

The parameters of the item; in a dictionary, its type is 'Node':

| name | type | size | default | description |
|---|---|---|---|---|
| **name** | String |  | '' | sensor's unique name |
| **nodeNumber** | NodeIndex |  | invalid (-1) | node number to which sensor is attached to |
| **writeToFile** | Bool |  | True | True: write sensor output to file; flag is ignored (interpreted as False), if fileName='' |
| **fileName** | String |  | '' | directory and file name for sensor file output; empty: no file is written; a relative name is placed in `exudyn.config.outputDirectory` if that is set; the directory is created if it does not exist |
| **outputVariableType** | OutputVariableType |  | OutputVariableType::_None | OutputVariableType for sensor |
| **storeInternal** | Bool |  | False | true: store sensor data in memory (faster, but may consume large amounts of memory); false: internal storage not available |
| **visualization** | VSensorNode |  |  | parameters for visualization of item |

## Visualization parameters

The parameters of `VSensorNode`, given as `visualization`:

| name | type | size | default | description |
|---|---|---|---|---|
| **show** | Bool |  | True | set true, if item is shown in visualization and false if it is not shown |

## Drawing

Drawn as [all sensors](#sec-drawing-sensors).
(description-sensornode)=
## Detailed description

### Attached to

The node `nodeNumber`: every node, with {ref}`ODE2 <ODE2>`, {ref}`ODE1 <ODE1>` or other coordinates.

### Measures

`outputVariableType` is one of the output variables of the node, as its page lists them under
**Output variables** - `Position`, `Velocity`, `Coordinates`, and for a rigid body node also
`RotationMatrix`, `AngularVelocity` and the like. The frame is the one the node page gives for the
variable.

(miniexample-sensornode)=
## Mini example


```python
#the position of a node, stored during the simulation
node = mbs.AddNode(NodePoint(referenceCoordinates=[0,0,0], initialVelocities=[1,0,0]))
mbs.AddObject(ObjectMassPoint(nodeNumber=node, mass=1))
sNode = mbs.AddSensor(SensorNode(nodeNumber=node, outputVariableType=exu.OutputVariableType.Position,
                                 storeInternal=True, writeToFile=False))

mbs.Assemble()
mbs.SolveDynamic()

#rows [t, x, y, z]; the last row at t=1
data = mbs.GetSensorStoredData(sNode)
exu.sys['testResult'] = data[-1,0] + data[-1,1] #1+1
```


Examples (Ex) and TestModels (TM) that show this item, with weblink to github: [`plotSensorExamples.py`](https://github.com/jgerstmayr/EXUDYN/blob/master/python/Examples/plotSensorExamples.py) (Ex), [`sensorUserFunctionTest.py`](https://github.com/jgerstmayr/EXUDYN/blob/master/python/TestModels/sensorUserFunctionTest.py) (TM), [`springDamperUserFunctionTest.py`](https://github.com/jgerstmayr/EXUDYN/blob/master/python/TestModels/springDamperUserFunctionTest.py) (TM), [`rigidBodyCOMtest.py`](https://github.com/jgerstmayr/EXUDYN/blob/master/python/TestModels/rigidBodyCOMtest.py) (TM), [`plotSensorTest.py`](https://github.com/jgerstmayr/EXUDYN/blob/master/python/TestModels/plotSensorTest.py) (TM)