kinematicTreePendulum.rst

kinematicTreePendulum.py

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

#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# This is an EXUDYN python utility library
#
# Details:  test of MarkerKinematicTreeRigid in combination with loads and joint
#
# Author:   Johannes Gerstmayr
# Date:     2022-05-29
#
# 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
from exudyn.FEM import *

import numpy as np

from math import pi, sin, cos#, sqrt
from copy import copy, deepcopy
from exudyn.robotics import *

SC = exu.SystemContainer()
mbs = SC.AddSystem()

useGraphics = True

gGround =  graphics.CheckerBoard(point= [0,0,-2], size = 12)
objectGround = mbs.AddObject(ObjectGround(referencePosition = [0,0,0],
                                          visualization=VObjectGround(graphicsData=[gGround])))

L = 0.5 #length
w = 0.1 #width of links

gravity3D = [0,-9.81*1,0]
graphicsBaseList = [graphics.Brick(size=[L*4, 0.8*w, 0.8*w], color=graphics.color.grey)] #rail

newRobot = Robot(gravity=gravity3D,
              base = RobotBase(visualization=VRobotBase(graphicsData=graphicsBaseList)),
              tool = RobotTool(HT=HTtranslate([0,0.5*L,0]), visualization=VRobotTool(graphicsData=[
                  graphics.Brick(size=[w, L, w], color=graphics.color.orange)])),
              referenceConfiguration = []) #referenceConfiguration created with 0s automatically

linksList = []

nChainLinks = 1 #5
for i in range(nChainLinks):
    Jlink = InertiaCuboid(density=1000, sideLengths=[w,L,w]) #w.r.t. reference center of mass
    Jlink = Jlink.Translated([0,0.5*L,0])
    preHT = HT0()
    if i > 0:
        preHT = HTtranslateY(L)

    link = RobotLink(Jlink.Mass(), Jlink.COM(), Jlink.InertiaCOM(),
                     jointType='Rz', preHT=preHT,
                     #PDcontrol=(pControl*0, dControl*0),
                     visualization=VRobotLink(linkColor=graphics.color.blue))
    newRobot.AddLink(link)
    linksList += [copy(link)]

#newRobot.referenceConfiguration[0] = 0.5*0
# for i in range(nChainLinks):
#     newRobot.referenceConfiguration[i+1] = (2*pi/360) * 5
newRobot.referenceConfiguration[0] = -(2*pi/360) * 90 #-0.5*pi
# newRobot.referenceConfiguration[2] = (2*pi/360) * 12 #-0.5*pi


dKT = newRobot.CreateKinematicTree(mbs)
oKT = dKT['objectKinematicTree']

sCoords=mbs.AddSensor(SensorBody(bodyNumber=oKT, storeInternal=True,
                    outputVariableType=exu.OutputVariableType.Coordinates))

mbs.Assemble()

simulationSettings = exu.SimulationSettings()

tEnd = 2000
h = 1e-2#*0.01
#tEnd = h

simulationSettings.timeIntegration.numberOfSteps = int(tEnd/h)
simulationSettings.timeIntegration.endTime = tEnd
simulationSettings.solutionSettings.writeSolutionToFile=False
simulationSettings.solutionSettings.sensorsWritePeriod = 0.05
simulationSettings.timeIntegration.verboseMode = 1

simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.95 #SHOULD work with 0.9 as well

SC.visualizationSettings.general.autoFitScene=False
SC.visualizationSettings.window.renderWindowSize = [1600,1200]
SC.visualizationSettings.general.drawCoordinateSystem=True
SC.visualizationSettings.general.drawWorldBasis=True
SC.visualizationSettings.openGL.multiSampling=4
SC.visualizationSettings.nodes.showBasis = True
SC.visualizationSettings.nodes.basisSize = 0.5

if useGraphics:

    exu.StartRenderer()
    if 'renderState' in exu.sys: SC.SetRenderState(exu.sys['renderState']) #load last model view

    mbs.WaitForUserToContinue() #press space to continue




mbs.SolveDynamic(simulationSettings, solverType = exu.DynamicSolverType.ExplicitMidpoint)
mbs.PlotSensor(sensorNumbers=sCoords, components=0, labels='Explicit Midpoint', colorCodeOffset=2, closeAll=True)

mbs.SolveDynamic(simulationSettings, solverType = exu.DynamicSolverType.RK33)
mbs.PlotSensor(sensorNumbers=sCoords, components=0, labels='Heun', colorCodeOffset=1, newFigure=False)

mbs.SolveDynamic(simulationSettings, solverType = exu.DynamicSolverType.RK44)
mbs.PlotSensor(sensorNumbers=sCoords, components=0, labels='Runge Kutta 44', newFigure=False)


#mbs.SolveDynamic(simulationSettings)

simulationSettings.timeIntegration.numberOfSteps = int(7/h)
simulationSettings.timeIntegration.endTime = 7
mbs.SolveDynamic(simulationSettings, solverType = exu.DynamicSolverType.ExplicitEuler)
mbs.PlotSensor(sensorNumbers=sCoords, components=0, yLabel='pendulum angle', labels=['Explicit Euler'], colorCodeOffset=3, newFigure=False)

if useGraphics:
    #SC.WaitForRenderEngineStopFlag()
    exu.StopRenderer() #safely close rendering window!