rigid3Dexample.py

You can view and download this file on Github: rigid3Dexample.py

  1#%%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2# This is an EXUDYN example
  3#
  4# Details:  A chain of 3D rigid bodies is simulated rigid bodies are connected via spring-dampers (no joints!)
  5#
  6# Author:   Johannes Gerstmayr
  7# Date:     2019-11-15
  8#
  9# 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.
 10#
 11#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 12
 13import exudyn as exu
 14from exudyn.itemInterface import *
 15from exudyn.utilities import *
 16
 17SC = exu.SystemContainer()
 18mbs = SC.AddSystem()
 19
 20print('EXUDYN version='+exu.GetVersionString())
 21
 22#%%+++++++++++++++++++++++++++++++++++
 23#background
 24#rect = [-0.1,-0.1,0.1,0.1] #xmin,ymin,xmax,ymax
 25#background0 = {'type':'Line', 'color':[0.1,0.1,0.8,1], 'data':[rect[0],rect[1],0, rect[2],rect[1],0, rect[2],rect[3],0, rect[0],rect[3],0, rect[0],rect[1],0]} #background
 26color = [0.1,0.1,0.8,1]
 27zz = 2*3 #max size
 28s = 0.1 #size of cube
 29sx = 3*s #x-size
 30cPosZ = 0.1 #offset of constraint in z-direction
 31
 32#create background, in order to have according zoom all
 33# background0 = GraphicsDataRectangle(-zz,-2*zz,zz,zz,color4white)
 34background0 = GraphicsDataCheckerBoard(point=[0,-0.5*zz,-0.25*zz],size=6*zz)
 35oGround=mbs.CreateGround(referencePosition= [0,0,0],
 36                         graphicsDataList = [background0])
 37mPosLast = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround,
 38                                            localPosition=[-2*sx,0,cPosZ]))
 39
 40#%%+++++++++++++++++++++++++++++++++++
 41#create a chain of bodies:
 42for i in range(20):
 43    #print("Build Object", i)
 44    f = 0 #factor for initial velocities
 45    omega0 = [0,50.*f,20*f] #arbitrary initial angular velocity
 46    ep0 = eulerParameters0 #no rotation
 47
 48    ep_t0 = AngularVelocity2EulerParameters_t(omega0, ep0)
 49
 50    p0 = [-sx+i*2*sx,0.,0] #reference position
 51    v0 = [0.2*f,0.,0.] #initial translational velocity
 52
 53    nRB = mbs.AddNode(NodeRigidBodyEP(referenceCoordinates=p0+ep0,
 54                                      initialVelocities=v0+list(ep_t0)))
 55    oGraphicsLines = GraphicsDataOrthoCubeLines(-0.9*sx,-s,-s, 0.9*sx,s,s, color=color4black)
 56    oGraphics = GraphicsDataOrthoCubePoint(size=[1.8*sx, 2*s, 2*s], color= color4dodgerblue)
 57    oGraphicsJoint = GraphicsDataSphere(point=[-sx,0,cPosZ], radius = 0.6*s, color=color4darkgrey, nTiles=24)
 58    oRB = mbs.AddObject(ObjectRigidBody(physicsMass=2,
 59                                        physicsInertia=[6,1,6,0,0,0],
 60                                        nodeNumber=nRB,
 61                                        visualization=VObjectRigidBody(graphicsData=[oGraphics, oGraphicsJoint, oGraphicsLines])))
 62
 63    mMassRB = mbs.AddMarker(MarkerBodyMass(bodyNumber = oRB))
 64    mbs.AddLoad(Gravity(markerNumber = mMassRB, loadVector=[0.,-9.81,0.])) #gravity in negative z-direction
 65
 66    k = 1e7
 67    d=0.01*k
 68    mPos = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oRB, localPosition = [-sx,0.,cPosZ]))
 69    mbs.AddObject(ObjectConnectorCartesianSpringDamper(markerNumbers = [mPosLast, mPos],
 70                                                       stiffness=[k,k,k], damping=[d,d,d])) #gravity in negative z-direction
 71    mPosLast = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oRB, localPosition = [sx,0.,cPosZ]))
 72
 73#%%+++++++++++++++++++++++++++++++++++
 74mbs.Assemble()
 75print(mbs)
 76
 77simulationSettings = exu.SimulationSettings() #takes currently set values or default values
 78
 79fact = 20000 #10000
 80simulationSettings.timeIntegration.numberOfSteps = 1*fact
 81simulationSettings.timeIntegration.endTime = 0.001*fact*0.5*4
 82simulationSettings.solutionSettings.solutionWritePeriod = simulationSettings.timeIntegration.endTime/fact*10
 83simulationSettings.timeIntegration.verboseMode = 1
 84
 85simulationSettings.timeIntegration.newton.useModifiedNewton = True
 86simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.6 #0.6 works well
 87simulationSettings.linearSolverType = exu.LinearSolverType.EigenSparse
 88
 89simulationSettings.solutionSettings.solutionInformation = "rigid body tests"
 90SC.visualizationSettings.nodes.defaultSize = 0.05
 91SC.visualizationSettings.openGL.multiSampling = 4
 92SC.visualizationSettings.openGL.lineWidth = 2
 93
 94# uncomment following line for shadow:
 95# SC.visualizationSettings.openGL.shadow = 0.5
 96# SC.visualizationSettings.openGL.light0position = [4,4,10,0]
 97
 98exu.StartRenderer()
 99mbs.WaitForUserToContinue()
100
101mbs.SolveDynamic(simulationSettings)
102
103SC.WaitForRenderEngineStopFlag()
104exu.StopRenderer() #safely close rendering window!