SensorMarker

A sensor attached to a marker, which measures what the marker provides, in the current configuration.

Parameters

The parameters of the item; in a dictionary, its type is ‘Marker’:

name	type	default	description
name	String	‘’	sensor’s unique name
markerNumber	MarkerIndex	invalid (-1)	marker 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; output variables are only possible according to markertype, see general description of SensorMarker
storeInternal	Bool	False	true: store sensor data in memory (faster, but may consume large amounts of memory); false: internal storage not available
visualization	VSensorMarker		parameters for visualization of item

Visualization parameters

The parameters of VSensorMarker, 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.

Detailed description

Attached to

The marker markerNumber, any kind of marker.

Measures

What the marker provides, which depends on its types; the coordinates only in the current configuration:

the marker provides	`outputVariableType` can be
a position (`MarkerBodyPosition`, `MarkerNodePosition`, …)	`Position`, `Displacement`, `Velocity`
an orientation (`MarkerBodyRigid`, `MarkerNodeRigid`, …)	in addition `RotationMatrix`, `Rotation`, `AngularVelocity`, `AngularVelocityLocal`, `HomogeneousTransformation`
coordinates (`MarkerNodeCoordinate`, `MarkerNodeCoordinates`, …)	`Coordinates`, `Coordinates_t`
a relative coordinate of two bodies	`Coordinates`, `Coordinates_t`

Markers have no output variables of their own, which is why this sensor lists them here.

Mini example

#what a marker provides, here the velocity of a point of a body
node = mbs.AddNode(NodePoint(referenceCoordinates=[0,0,0], initialVelocities=[0,2,0]))
body = mbs.AddObject(ObjectMassPoint(nodeNumber=node, mass=1))
mBody = mbs.AddMarker(MarkerBodyPosition(bodyNumber=body, localPosition=[0,0,0]))
mbs.AddLoad(LoadForceVector(markerNumber=mBody, loadVector=[0,-1,0]))
sVelocity = mbs.AddSensor(SensorMarker(markerNumber=mBody, outputVariableType=exu.OutputVariableType.Velocity,
                                       storeInternal=True, writeToFile=False))

mbs.Assemble()
mbs.SolveDynamic()

#v = v0 + F/m*t at t=1
exu.sys['testResult'] = mbs.GetSensorValues(sVelocity)[1] #1

Examples (Ex) and TestModels (TM) that show this item, with weblink to github: plotSensorTest.py (TM), pendulumFriction.py (TM)