MarkerNodeCoordinate

A node-Marker attached to a ODE2 coordinate of a node; this marker allows to connect a coordinate-based constraint or connector to a nodal coordinate (also NodeGround); for ODE1 coordinates use MarkerNodeODE1Coordinate.

Interface

Provides: Coordinate
Connectors, constraints and loads that can use it: ObjectConnectorCoordinateSpringDamper, ObjectConnectorCoordinateSpringDamperExt, ObjectConnectorCoordinate, ObjectContactCoordinate, LoadCoordinate

Parameters

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

name	type	default	description
name	String	‘’	marker’s unique name
nodeNumber	NodeIndex	invalid (-1)	node number to which marker is attached to
coordinate	UInt	invalid (-1)	coordinate of node to which marker is attached to; must be given: the default is only a placeholder
visualization	VMarkerNodeCoordinate		parameters for visualization of item

Visualization parameters

VMarkerNodeCoordinate has no parameters.

Drawing

The item draws nothing.

Detailed description

Marker quantities

quantity	symbol	as computed
coordinate	\(c = q_i\)	the current ODE2 coordinate `coordinate` \(= i\) of the node, without its reference value
its velocity	\(\dot c = \dot q_i\)	the time derivative of that coordinate

Jacobians

\(\Jm = \ev_i\tp\), a row of the unit matrix: a force \(f\) acts on coordinate \(i\) only, \(Q_i = f\).

On a node without ODE2 coordinates - NodePointGround - the coordinate is zero and the Jacobian empty, so nothing acts: this is the ground side of a CoordinateSpringDamper or a CoordinateConstraint.

Mini example

#one coordinate of a node: a coordinate spring between the ground node and a 1D mass
node = mbs.AddNode(Node1D(referenceCoordinates=[0]))
mbs.AddObject(ObjectMass1D(nodeNumber=node, mass=1))
mCoord = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=node, coordinate=0))
mGround = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=nGround, coordinate=0))
mbs.AddObject(ObjectConnectorCoordinateSpringDamper(markerNumbers=[mGround, mCoord], stiffness=100))
mbs.AddLoad(LoadCoordinate(markerNumber=mCoord, load=10))

mbs.Assemble()
mbs.SolveStatic()

#the spring is stretched by F/k
exu.sys['testResult'] = mbs.GetNodeOutput(node, exu.OutputVariableType.Coordinates) #0.1

Examples (Ex) and TestModels (TM) that show this item, with weblink to github: tutorialSpringDamper.py (Ex), coordinateSpringDamper.py (Ex), SliderCrank.py (Ex), plotSensorExamples.py (Ex), SpringDamperMassUserFunction.py (Ex)