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/* -------------------------------------------------------------------------- *
* Simbody(tm) Example: Gears *
* -------------------------------------------------------------------------- *
* This is part of the SimTK biosimulation toolkit originating from *
* Simbios, the NIH National Center for Physics-Based Simulation of *
* Biological Structures at Stanford, funded under the NIH Roadmap for *
* Medical Research, grant U54 GM072970. See https://simtk.org/home/simbody. *
* *
* Portions copyright (c) 2008-12 Stanford University and the Authors. *
* Authors: Michael Sherman *
* Contributors: *
* *
* Licensed under the Apache License, Version 2.0 (the "License"); you may *
* not use this file except in compliance with the License. You may obtain a *
* copy of the License at http://www.apache.org/licenses/LICENSE-2.0. *
* *
* Unless required by applicable law or agreed to in writing, software *
* distributed under the License is distributed on an "AS IS" BASIS, *
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
* See the License for the specific language governing permissions and *
* limitations under the License. *
* -------------------------------------------------------------------------- */
#include "Simbody.h"
using namespace SimTK;
int main() {
// Create the system.
MultibodySystem system;
SimbodyMatterSubsystem matter(system);
// Create bodies.
Body::Rigid gearBody(MassProperties(1.0, Vec3(0), Inertia(1)));
gearBody.addDecoration(Transform(Rotation(0.5*Pi, XAxis)),
DecorativeCylinder(1.0, 0.1));
Body::Rigid rodBody(MassProperties(1.0, Vec3(0), Inertia(1)));
rodBody.addDecoration(Transform(Vec3(0, 1, 0)), DecorativeCylinder(0.05, 1.0));
// Create instances of the bodies that are connected into the multibody
// system via Mobilizers. Note that we use the gear body twice.
MobilizedBody::Pin gear1(matter.updGround(), Transform(Vec3(1, 0, 0)),
gearBody, Transform());
MobilizedBody::Pin gear2(matter.updGround(), Transform(Vec3(-1, 0, 0)),
gearBody, Transform());
MobilizedBody::Pin rod(gear2, Transform(Vec3(0, 0.8, 0.1)), rodBody, Transform());
// Add constraints.
Constraint::ConstantSpeed(gear1, 2*Pi); // i.e., 1 rotation per second
Constraint::NoSlip1D(matter.updGround(), Vec3(0), UnitVec3(0, 1, 0), gear1, gear2);
// We want the rod end point traveling along a line. We'll draw part of the
// line to make it clear.
Constraint::PointOnLine(matter.updGround(), UnitVec3(0, 1, 0), Vec3(0, 0, 0.1),
rod, Vec3(0, 2, 0));
matter.updGround().addBodyDecoration(Vec3(0,0,.1),
DecorativeLine(Vec3(0), 3*UnitVec3(0,1,0))
.setColor(Red));
// Visualize the system, reporting an output frame every 1/30 of a simulated
// second. The Visualizer's default frame rate is 30fps, and it will slow the
// simulation down to keep to that speed, so we'll get exactly real time
// this way. We don't want the default ground and sky background here.
Visualizer viz(system);
viz.setBackgroundType(Visualizer::SolidColor); // default is white
system.addEventReporter(new Visualizer::Reporter(viz, 1./30));
// Initialize the system and state.
system.realizeTopology();
State state = system.getDefaultState();
// Simulate it.
RungeKuttaMersonIntegrator integ(system);
TimeStepper ts(system, integ);
ts.initialize(state);
ts.stepTo(1000.0);
}
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