.. _examples-rigidpendulum:

****************
rigidPendulum.py
****************

You can view and download this file on Github: `rigidPendulum.py <https://github.com/jgerstmayr/EXUDYN/tree/master/main/pythonDev/Examples/rigidPendulum.py>`_

.. code-block:: python
   :linenos:

   #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   # This is an EXUDYN example
   #
   # Details:  Example 2D rigid pendulum
   #
   # Author:   Johannes Gerstmayr
   # Date:     2019-08-15
   #
   # 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 exudyn.graphics as graphics #only import if it does not conflict
   
   SC = exu.SystemContainer()
   mbs = SC.AddSystem()
   
   
   #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   #rigid pendulum:
   L = 1    #x-dim of pendulum
   b = 0.1  #y-dim of pendulum
   background = graphics.CheckerBoard(point=[-1,0.5,0],size=2)
   oGround=mbs.AddObject(ObjectGround(referencePosition= [0,0,0], visualization=VObjectGround(graphicsData= [background])))
   massRigid = 12
   inertiaRigid = massRigid/12*(L)**2
   g = 9.81    # gravity
   
   graphicsCube = graphics.Brick(size= [L,b,b], color= graphics.color.dodgerblue, addEdges=True)
   graphicsJoint = graphics.Cylinder(pAxis=[-0.5*L,0,-0.6*b], vAxis= [0,0,1.2*b], radius = 0.55*b, color=graphics.color.darkgrey, addEdges=True)
   nRigid = mbs.AddNode(Rigid2D(referenceCoordinates=[-0.5*L,L,0], initialVelocities=[0,0,2]));
   oRigid = mbs.AddObject(RigidBody2D(physicsMass=massRigid, physicsInertia=inertiaRigid,nodeNumber=nRigid,
                                      visualization=VObjectRigidBody2D(graphicsData= [graphicsCube, graphicsJoint])))
   
   mR1 = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oRigid, localPosition=[-0.5*L,0.,0.])) #support point
   mRcom = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oRigid, localPosition=[ 0.,0.,0.])) #COM point
   
   mG0 = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oGround, localPosition=[-L,L,0.]))
   mbs.AddObject(RevoluteJoint2D(markerNumbers=[mG0,mR1]))
   
   mbs.AddLoad(Force(markerNumber = mRcom, loadVector = [0, -massRigid*g, 0]))
   
   mbs.Assemble()
   print(mbs)
   
   simulationSettings = exu.SimulationSettings() #takes currently set values or default values
   
   simulationSettings.timeIntegration.numberOfSteps = 1000000
   simulationSettings.timeIntegration.endTime = 2000
   simulationSettings.timeIntegration.startTime = 0
   simulationSettings.timeIntegration.newton.relativeTolerance = 1e-8*100 #10000
   simulationSettings.timeIntegration.newton.absoluteTolerance = 1e-10
   simulationSettings.timeIntegration.verboseMode = 1
   
   simulationSettings.timeIntegration.newton.useModifiedNewton = False
   simulationSettings.timeIntegration.newton.numericalDifferentiation.minimumCoordinateSize = 1
   simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.5
   simulationSettings.displayStatistics = True
   
   #SC.visualizationSettings.nodes.defaultSize = 0.05
   
   simulationSettings.solutionSettings.solutionInformation = "Rigid pendulum"
   SC.visualizationSettings.openGL.multiSampling = 4
   SC.visualizationSettings.openGL.lineWidth = 2
   
   exu.StartRenderer()
   
   mbs.SolveDynamic(simulationSettings)
   
   SC.WaitForRenderEngineStopFlag()
   exu.StopRenderer() #safely close rendering window!