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/*---------------------------------------------------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration |
\\ / A nd | Copyright (C) 2016 OpenFOAM Foundation
\\/ M anipulation |
-------------------------------------------------------------------------------
License
This file is part of OpenFOAM.
OpenFOAM is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
Application
pendulum
Description
Simple swinging pendulum simulation with 1-DoF. The motion is integrated
using a symplectic method for just over 2-periods.
\*---------------------------------------------------------------------------*/
#include "rigidBodyModel.H"
#include "masslessBody.H"
#include "rigidBodyModelState.H"
#include "sphere.H"
#include "joints.H"
#include "IFstream.H"
using namespace Foam;
using namespace RBD;
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
int main(int argc, char *argv[])
{
/*
bool testMerge = true;
// Create a model for the pendulum
rigidBodyModel pendulum;
// Join a weight to the origin with a centre of mass -1m below the origin
// by a hinge which rotates about the z-axis
if (testMerge)
{
pendulum.join
(
pendulum.bodyID("root"),
Xt(Zero),
joint::New(new joints::Rz()),
autoPtr<rigidBody>(new masslessBody("hinge"))
);
pendulum.merge
(
pendulum.bodyID("hinge"),
Xt(vector(0, -1, 0)),
autoPtr<rigidBody>(new sphere("weight", 1, 0.05))
);
}
else
{
pendulum.join
(
pendulum.bodyID("root"),
Xt(Zero),
joint::New(new joints::Rz()),
rigidBody::New("pendulum", 1, vector(0, -1, 0), 1e-3*I)
);
}
*/
// Create the pendulum model from dictionary
rigidBodyModel pendulum(dictionary(IFstream("pendulum")()));
Info<< pendulum << endl;
// Create the joint-space state fields
rigidBodyModelState pendulumState(pendulum);
scalarField& q = pendulumState.q();
scalarField& qDot = pendulumState.qDot();
scalarField& qDdot = pendulumState.qDdot();
scalarField tau(pendulum.nDoF(), Zero);
// Set the angle of the pendulum to 0.3rad
q[0] = 0.3;
// Set the gravitational acceleration
pendulum.g() = vector(0, -9.81, 0);
// Integrate the motion of the pendulum for 4.1s (~2-periods) using a
// symplectic method
scalar deltaT = 0.01;
for (scalar t=0; t<4.1; t+=deltaT)
{
qDot += 0.5*deltaT*qDdot;
q += deltaT*qDot;
pendulum.forwardDynamics(pendulumState, tau, Field<spatialVector>());
qDot += 0.5*deltaT*qDdot;
Info<< "Time " << t << "s, angle = " << q[0] << "rad" << endl;
}
Info<< "\nEnd\n" << endl;
return 0;
}
// ************************************************************************* //
|
