Introduction to Python (2)

Basic creation of a physical system and rigid bodies, using PyChrono.

• create a ChSystem
• create and add rigid bodies
• iterate on created contacts
• iterate on added rigid bodies using the Python syntax

#------------------------------------------------------------------------------
# Name:        pychrono example
# Purpose:
#
# Author:      Alessandro Tasora
#
# Created:     1/01/2019
# Copyright:   (c) ProjectChrono 2019
#------------------------------------------------------------------------------
 
print ("Second tutorial: create and populate a physical system");
 
 
# Load the Chrono::Engine core module!
import pychrono as chrono
 
 
# Create a physical system,
my_system = chrono.ChSystemNSC()
 
# Create a contact material, shared by all collision shapes
material = chrono.ChMaterialSurfaceNSC()
material.SetFriction(0.3)
material.SetCompliance(0)
 
# Add two bodies
my_shbodyA = chrono.ChBody()
my_shbodyA.SetMass(20)
my_shbodyA.SetName('BodyA')
my_shbodyA.SetInertiaXX( chrono.ChVectorD(10,10,10) )
print (my_shbodyA.GetInertia() )
my_shbodyA.SetPos(chrono.ChVectorD(1,-1,0))
my_shbodyA.GetCollisionModel().AddBox(material,10,1,10)
my_shbodyA.SetBodyFixed(True)
my_shbodyA.SetCollide(True)
 
my_shbodyB = chrono.ChBody()
my_shbodyB.SetName('BodyB')
my_shbodyB.SetPos(chrono.ChVectorD(0,2,0))
my_shbodyB.GetCollisionModel().AddBox(material,1,1,1)
my_shbodyB.SetCollide(True)
 
my_shmarker = chrono.ChMarker()
my_funct = chrono.ChFunction_Sine(0,0.5,3)
my_shmarker.SetMotion_X(my_funct)
my_shmarker.SetPos(chrono.ChVectorD(1,2,3))
my_shbodyB.AddMarker(my_shmarker)
 
my_system.Add(my_shbodyA)
my_system.Add(my_shbodyB)
 
 
 
# Add Contact callback (TO FIX!!)
 
 
# Report Contact callback
class MyReportContactCallback(chrono.ReportContactCallback):
    def __init__(self):
         chrono.ReportContactCallback.__init__(self)
    def OnReportContact(self,vA,vB,cA,dist,rad,force,torque,modA,modB):
         bodyUpA = chrono.CastContactableToChBody(modA)
         nameA = bodyUpA.GetName()
         bodyUpB = chrono.CastContactableToChBody(modB)
         nameB = bodyUpB.GetName()
         print ('  contact: point A=' , vA,  '  dist=',dist, 'Body A:', nameA, 'Body B:', nameB)
         return True        # return False to stop reporting contacts
 
my_rep = MyReportContactCallback()
 
 
 
# Simulation loop
my_system.SetChTime(0)
while (my_system.GetChTime() < 1.2) :
 
    my_system.DoStepDynamics(0.01)
 
    print ('time=', my_system.GetChTime(), ' bodyB y=', my_shbodyB.GetPos().y)
 
    my_system.GetContactContainer().ReportAllContacts(my_rep)
 
 
# Iterate over added bodies (Python style)
print ('Positions of all bodies in the system:')
for abody in my_system.Get_bodylist():
    print ('  body pos=', abody.GetPos() )
 
 
# Move a body, using a ChFrame
my_displacement = chrono.ChFrameMovingD(chrono.ChVectorD(5,1,0));
my_shbodyA %= my_displacement
# ..also as:
#  my_shbody.ConcatenatePreTransformation(my_displacement)
 
print ('Moved body pos=', my_shbodyA.GetPos() )
 
 
# Use a body with an auxiliary reference (REF) that does not correspond
# to the center of gravity (COG)
body_1= chrono.ChBodyAuxRef()
body_1.SetName('Parte1-1')
body_1.SetPos(chrono.ChVectorD(-0.0445347481124079,0.0676266363930238,-0.0230808979433518))
body_1.SetRot(chrono.ChQuaternionD(1,0,0,0))
body_1.SetMass(346.17080777653)
body_1.SetInertiaXX(chrono.ChVectorD(48583.2418823358,526927.118351673,490689.966726565))
body_1.SetInertiaXY(chrono.ChVectorD(1.70380722975012e-11,1.40840344485366e-11,-2.31869065456271e-12))
body_1.SetFrame_COG_to_REF(chrono.ChFrameD(chrono.ChVectorD(68.9923703887577,-60.1266363930238,70.1327223302498),chrono.ChQuaternionD(1,0,0,0)))
myasset = chrono.ChObjShapeFile()
myasset.SetFilename("shapes/test.obj")
body_1.GetAssets().push_back(myasset)
 
print ('Done...')