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

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

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

#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# This is an EXUDYN example
#
# Details:  An inactive connector (activeConnector = False) adds no force, and reports none (#984):
#           each penalty connector and contact between the ground and a rigid body that is displaced,
#           rotated and moving, built once inactive - its Force, ForceLocal, Torque and TorqueLocal
#           output must be zero - and once active, where they are not.
#
# Author:   Johannes Gerstmayr
# Date:     2026-10-05
#
# 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

import numpy as np

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

forceTypes = [exu.OutputVariableType.Force, exu.OutputVariableType.ForceLocal,
              exu.OutputVariableType.Torque, exu.OutputVariableType.TorqueLocal]


def DataNode(mbs, n):
    #the first data coordinate of the contacts is the gap of the last step: negative, in contact
    return mbs.AddNode(NodeGenericData(numberOfDataCoordinates=n, initialCoordinates=[-0.1]+[0]*(n-1)))


#each connector between a ground marker and a body marker (rigid or coordinate), with a force where it is active
connectors = {
    'SpringDamper': lambda mbs, mG, mB, cG, cB, active: mbs.AddObject(SpringDamper(markerNumbers=[mG, mB],
        stiffness=100, damping=1, referenceLength=1, activeConnector=active)),
    'CartesianSpringDamper': lambda mbs, mG, mB, cG, cB, active: mbs.AddObject(CartesianSpringDamper(
        markerNumbers=[mG, mB], stiffness=[100]*3, damping=[1]*3, activeConnector=active)),
    'RigidBodySpringDamper': lambda mbs, mG, mB, cG, cB, active: mbs.AddObject(RigidBodySpringDamper(
        markerNumbers=[mG, mB], stiffness=100*np.eye(6), damping=np.eye(6), activeConnector=active)),
    'TorsionalSpringDamper': lambda mbs, mG, mB, cG, cB, active: mbs.AddObject(TorsionalSpringDamper(
        markerNumbers=[mG, mB], stiffness=100, damping=1, activeConnector=active)),
    'LinearSpringDamper': lambda mbs, mG, mB, cG, cB, active: mbs.AddObject(LinearSpringDamper(
        markerNumbers=[mG, mB], stiffness=100, damping=1, activeConnector=active)),
    'CoordinateSpringDamper': lambda mbs, mG, mB, cG, cB, active: mbs.AddObject(CoordinateSpringDamper(
        markerNumbers=[cG, cB], stiffness=100, damping=1, activeConnector=active)),
    'ConnectorGravity': lambda mbs, mG, mB, cG, cB, active: mbs.AddObject(ObjectConnectorGravity(
        markerNumbers=[mG, mB], mass0=1e10, mass1=1, activeConnector=active)),
    'ContactSphereSphere': lambda mbs, mG, mB, cG, cB, active: mbs.AddObject(ObjectContactSphereSphere(
        markerNumbers=[mG, mB], nodeNumber=DataNode(mbs, 4), spheresRadii=[1, 1], contactStiffness=100,
        contactDamping=1, dynamicFriction=0.2, activeConnector=active)),
    'ContactSphereTriangle': lambda mbs, mG, mB, cG, cB, active: mbs.AddObject(ObjectContactSphereTriangle(
        markerNumbers=[mB, mG], nodeNumber=DataNode(mbs, 4), sphereRadius=1,
        trianglePoints=exu.Vector3DList([[0, -2, 0], [3, -2, 0], [0, 2, 0]]), contactStiffness=100,
        contactDamping=1, dynamicFriction=0.2, activeConnector=active)),
    }


def ForceOutputs(build, active):
    """the norms of the force and torque outputs a connector has, as a dict"""
    SC = exu.SystemContainer()
    mbs = SC.AddSystem()
    oGround = mbs.AddObject(ObjectGround())
    node = mbs.AddNode(NodeRigidBodyEP(referenceCoordinates=[1.2, 0.1, -0.05] + list(RotXYZ2EulerParameters([0.1, 0.2, 0.3])),
                                       initialVelocities=[0.3, 0.2, 0.1, 0, 0, 0, 0]))
    body = mbs.AddObject(ObjectRigidBody(nodeNumber=node, mass=1, inertia=[1, 1, 1, 0, 0, 0]))
    mG = mbs.AddMarker(MarkerBodyRigid(bodyNumber=oGround))
    mB = mbs.AddMarker(MarkerBodyRigid(bodyNumber=body))
    cG = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=mbs.AddNode(NodePointGround()), coordinate=0))
    cB = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=node, coordinate=0))
    connector = build(mbs, mG, mB, cG, cB, active)
    mbs.Assemble()
    outputs = {}
    for variableType in forceTypes:
        try:
            outputs[variableType] = np.linalg.norm(mbs.GetObjectOutput(connector, variableType))
        except Exception:
            pass    #the connector does not have this output variable
    return outputs


testResult = 0
for (name, build) in connectors.items():
    inactive = ForceOutputs(build, False)
    active = ForceOutputs(build, True)
    exu.Print(name + ': inactive', sum(inactive.values()), ', active', sum(active.values()))
    testResult += 1000*sum(inactive.values()) + sum(active.values())    #an inactive force spoils the result

exu.Print('solution of inactiveConnectorForceTest=', testResult)
exu.sys['testResult'] = testResult
```