<!-- GENERATED by tools/generators/examplesDocsEmitter.py from python/ - do not edit -->
(testmodels-coordinatespringdamperextvelocityoffsettest)=
# coordinateSpringDamperExtVelocityOffsetTest.py

You can view and download this file on Github: [coordinateSpringDamperExtVelocityOffsetTest.py](https://github.com/jgerstmayr/EXUDYN/tree/master/python/TestModels/coordinateSpringDamperExtVelocityOffsetTest.py)

```{code-block} python
:linenos:

#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# This is an EXUDYN example
#
# Details:  The velocityOffset of ObjectConnectorCoordinateSpringDamperExt in the built-in force law
#           k*(q - x_off) + d*(v - v_off) (#2867): a mass on a damper to the ground, started at rest, is driven by the
#           damper to the velocity v_off - after many time constants m/d its velocity is v_off.
#
# Author:   Johannes Gerstmayr
# Date:     2026-10-07
#
# Copyright:This file is part of Exudyn. Exudyn is free software. You can redistribute it and/or modify it under the terms of the Exudyn license. See 'LICENSE.txt' for more details.
#
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

import exudyn as exu
from exudyn.utilities import * #includes itemInterface and rigidBodyUtilities

testIsActive = exu.sys.get('testIsActive', False)

mass, damping, velocityOffset = 1., 50., 0.7

SC = exu.SystemContainer()
mbs = SC.AddSystem()
nGround = mbs.AddNode(NodePointGround())
node = mbs.AddNode(Node1D(referenceCoordinates=[0], initialCoordinates=[0], initialVelocities=[0]))
mbs.AddObject(ObjectMass1D(nodeNumber=node, mass=mass))
mGround = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=nGround, coordinate=0))
mNode = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=node, coordinate=0))
nData = mbs.AddNode(NodeGenericData(numberOfDataCoordinates=3, initialCoordinates=[0,0,0]))
mbs.AddObject(ObjectConnectorCoordinateSpringDamperExt(markerNumbers=[mGround, mNode], nodeNumber=nData,
                                                       stiffness=0, damping=damping, velocityOffset=velocityOffset))
mbs.Assemble()

simulationSettings = exu.SimulationSettings()
simulationSettings.timeIntegration.numberOfSteps = 1000
simulationSettings.timeIntegration.endTime = 1 #50 time constants m/d
simulationSettings.timeIntegration.verboseMode = 0
simulationSettings.solution.file.write = False
mbs.SolveDynamic(simulationSettings)

velocity = mbs.GetNodeOutput(node, exu.OutputVariableType.Coordinates_t) #a float, one coordinate
exu.Print('velocity', velocity, ', expected', velocityOffset)
errors = int(abs(velocity - velocityOffset) > 1e-8)
exu.Print('coordinateSpringDamperExtVelocityOffsetTest: errors', errors)
u = errors + velocity
exu.Print('solution of coordinateSpringDamperExtVelocityOffsetTest=', u)
exu.sys['testResult'] = u
```