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

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

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

#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# This is an EXUDYN example
#
# Details:  Test model for CreateRollingDisc; simple model of a wheel
#
# Author:   Johannes Gerstmayr
# Date:     2025-03-05
#
# 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 exudyn.graphics as graphics

import numpy as np

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

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

r = 0.2
oDisc = mbs.CreateRigidBody(inertia = InertiaCylinder(density=5000, length=0.02, outerRadius=r, axis=0),
                          referencePosition = [1,0,r],
                          initialAngularVelocity = [-3*2*pi,10,0],
                          initialVelocity = [0,r*3*2*pi,0],
                          gravity = [0,0,-9.81],
                          graphicsDataList = [exu.graphics.Cylinder(pAxis = [-0.01,0,0], vAxis = [0.02,0,0], radius = r*0.99, nTiles=32,
                                                                    color=exu.graphics.color.blue),
                                              exu.graphics.Basis(length=2*r)])
oGround = mbs.CreateGround(graphicsDataList=[exu.graphics.CheckerBoard(size=8)])

mbs.CreateRollingDisc(bodyNumbers=[oGround, oDisc], 
                      axisPosition=[0,0,0], axisVector=[1,0,0], #on local wheel frame
                      planePosition = [0,0,0], planeNormal = [0,0,1],  #in ground frame
                      discRadius = r, 
                      discWidth=0.01, color=exu.graphics.color.steelblue)

mbs.Assemble()

simulationSettings = exu.SimulationSettings() #takes currently set values or default values


stepSize=0.002
tEnd = 1

simulationSettings.timeIntegration.numberOfSteps = int(tEnd/stepSize)
simulationSettings.timeIntegration.endTime = tEnd
simulationSettings.solution.file.write = (not testIsActive)
simulationSettings.timeIntegration.verboseMode = 1
simulationSettings.timeIntegration.newton.useModifiedNewton = True

SC.visualizationSettings.nodes.show = True
SC.visualizationSettings.nodes.drawNodesAsPoint  = False
SC.visualizationSettings.nodes.showBasis = True
SC.visualizationSettings.nodes.basisSize = 0.015
SC.visualizationSettings.view0.camera.perspective = 1
SC.visualizationSettings.openGL.light0.shadow=0.3
SC.visualizationSettings.openGL.multiSampling=4

if not testIsActive:
    SC.renderer.Start()
    SC.renderer.DoIdleTasks()

mbs.SolveDynamic(simulationSettings)

p0=mbs.GetObjectOutputBody(oDisc, exu.OutputVariableType.Position)

u = np.linalg.norm(p0)
exu.Print('solution of createRollingDisc=',u) 

exu.sys['testResult'] = u


if not testIsActive:
    SC.renderer.DoIdleTasks()
    SC.renderer.Stop() #safely close rendering window!

# mbs.SolutionViewer()
```