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/* -------------------------------------------------------------------------- *
* Simbody(tm) *
* -------------------------------------------------------------------------- *
* 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: Peter Eastman *
* 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;
using namespace std;
void testCalculationMethods() {
// Create a system with two bodies.
MultibodySystem system;
SimbodyMatterSubsystem matter(system);
GeneralForceSubsystem forces(system);
Body::Rigid body(MassProperties(1.0, Vec3(0), Inertia(1)));
MobilizedBody::Free b1(matter.Ground(), body);
MobilizedBody::Free b2(matter.Ground(), body);
// Set all the state variables to random values.
system.realizeTopology();
State state = system.getDefaultState();
Random::Gaussian random;
for (int i = 0; i < state.getNY(); ++i)
state.updY()[i] = random.getValue();
system.realize(state, Stage::Acceleration);
// Test the low level methods for transforming points and vectors.
const Vec3 point(0.5, 1, -1.5);
SimTK_TEST_EQ(b1.findStationLocationInGround(state, Vec3(0)), b1.getBodyOriginLocation(state));
SimTK_TEST_EQ(b1.findStationAtGroundPoint(state, b1.findStationLocationInGround(state, point)), point);
SimTK_TEST_EQ(b2.findStationAtGroundPoint(state, b1.findStationLocationInGround(state, point)), b1.findStationLocationInAnotherBody(state, point, b2));
SimTK_TEST_EQ(b2.findStationAtGroundPoint(state, b1.findStationLocationInGround(state, Vec3(0))).norm(), (b1.getBodyOriginLocation(state)-b2.getBodyOriginLocation(state)).norm());
SimTK_TEST_EQ(b2.findMassCenterLocationInGround(state), b2.findStationLocationInGround(state, b2.getBodyMassCenterStation(state)));
SimTK_TEST_EQ(b1.expressVectorInGroundFrame(state, Vec3(0)), Vec3(0));
SimTK_TEST_EQ(b1.expressVectorInGroundFrame(state, point), b1.getBodyRotation(state)*point);
SimTK_TEST_EQ(b1.expressGroundVectorInBodyFrame(state, b1.expressVectorInGroundFrame(state, point)), point);
SimTK_TEST_EQ(b2.expressGroundVectorInBodyFrame(state, b1.expressVectorInGroundFrame(state, point)), b1.expressVectorInAnotherBodyFrame(state, point, b2));
// Test the routines for mapping locations, velocities, and accelerations.
Vec3 r, v, a;
b1.findStationLocationVelocityAndAccelerationInGround(state, point, r, v, a);
SimTK_TEST_EQ(v, b1.findStationVelocityInGround(state, point));
SimTK_TEST_EQ(a, b1.findStationAccelerationInGround(state, point));
{
Vec3 r2, v2;
b1.findStationLocationAndVelocityInGround(state, point, r2, v2);
SimTK_TEST_EQ(r, r2);
SimTK_TEST_EQ(v, v2);
}
SimTK_TEST_EQ(b1.findStationVelocityInGround(state, Vec3(0)), b1.getBodyOriginVelocity(state));
SimTK_TEST_EQ(b1.findStationAccelerationInGround(state, Vec3(0)), b1.getBodyOriginAcceleration(state));
SimTK_TEST_EQ(b1.findStationVelocityInGround(state, point), b1.findStationVelocityInAnotherBody(state, point, matter.Ground()));
}
void testWeld() {
MultibodySystem system;
SimbodyMatterSubsystem matter(system);
GeneralForceSubsystem forces(system);
Force::UniformGravity gravity(forces, matter, Vec3(0, -1, 0));
Body::Rigid body(MassProperties(1.0, Vec3(0), Inertia(1)));
// Create two pendulums, each with two welded bodies. One uses a Weld MobilizedBody,
// and the other uses a Weld constraint.
Transform inboard(Vec3(0.1, 0.5, -1));
Transform outboard(Vec3(0.2, -0.2, 0));
MobilizedBody::Ball p1(matter.updGround(), Vec3(0), body, Vec3(0, 1, 0));
MobilizedBody::Ball p2(matter.updGround(), Vec3(0), body, Vec3(0, 1, 0));
MobilizedBody::Weld c1(p1, inboard, body, outboard);
MobilizedBody::Free c2(p2, inboard, body, outboard);
Constraint::Weld constraint(p2, inboard, c2, outboard);
// It is not a general test unless the Weld mobilizer has children!
MobilizedBody::Pin wchild1(c1, inboard, body, outboard);
MobilizedBody::Pin wchild2(c2, inboard, body, outboard);
Force::MobilityLinearSpring(forces, wchild1, 0, 1000, 0);
Force::MobilityLinearSpring(forces, wchild2, 0, 1000, 0);
State state = system.realizeTopology();
p1.setU(state, Vec3(1, 2, 3));
p2.setU(state, Vec3(1, 2, 3));
system.realize(state, Stage::Velocity);
system.project(state, 1e-10);
SimTK_TEST_EQ(c1.getBodyTransform(state), c2.getBodyTransform(state));
SimTK_TEST_EQ(c1.getBodyVelocity(state), c2.getBodyVelocity(state));
// Simulate it and see if both pendulums behave identically.
RungeKuttaMersonIntegrator integ(system);
TimeStepper ts(system, integ);
ts.initialize(state);
ts.stepTo(5);
system.realize(integ.getState(), Stage::Velocity);
SimTK_TEST_EQ_TOL(c1.getBodyTransform(integ.getState()),
c2.getBodyTransform(integ.getState()), 1e-10);
SimTK_TEST_EQ_TOL(c1.getBodyVelocity(integ.getState()),
c2.getBodyVelocity(integ.getState()), 1e-10);
}
// Create two pendulums with gimbal joints, one where the gimbals are faked
// with a series of pin joints that should provide identical generalized
// coordinates and speeds (we're expecting the new gimbal definition in which
// the generalized speeds are the Euler angle derivatives).
void testGimbal() {
MultibodySystem system;
SimbodyMatterSubsystem matter(system);
GeneralForceSubsystem forces(system);
Force::UniformGravity gravity(forces, matter, Vec3(0, -9.81, 0));
Body::Rigid lumpy(MassProperties(3.1, Vec3(.1, .2, .3),
UnitInertia(1.2,1.1,1.3,.01,.02,.03)));
Body::Rigid massless(MassProperties(0,Vec3(0),UnitInertia(0)));
Vec3 inboard(0.1, 0.5, -1);
Vec3 outboard(0.2, -0.2, 0);
MobilizedBody::Gimbal p1(matter.updGround(), inboard, lumpy, outboard);
Rotation axisX(Pi/2, YAxis); // rotate z into x
Rotation axisY(-Pi/2, XAxis); // rotate z into y
Rotation axisZ; // leave z where it is
MobilizedBody::Pin dummy1(matter.updGround(), Transform(axisX,inboard),
massless, Transform(axisX, Vec3(0)));
MobilizedBody::Pin dummy2(dummy1, Transform(axisY, Vec3(0)),
massless, Transform(axisY, Vec3(0)));
MobilizedBody::Pin p2(dummy2, Transform(axisZ, Vec3(0)),
lumpy, Transform(axisZ, outboard));
MobilizedBody::Weld c1(p1, inboard, lumpy, outboard);
MobilizedBody::Weld c2(p2, inboard, lumpy, outboard);
c1.addBodyDecoration(Transform(), DecorativeBrick(.1*Vec3(1,2,3))
.setColor(Cyan).setOpacity(0.2));
c2.addBodyDecoration(Transform(), DecorativeBrick(.1*Vec3(1,2,3))
.setColor(Red).setRepresentation(DecorativeGeometry::DrawWireframe));
//Visualizer viz(system); viz.setBackgroundType(Visualizer::SolidColor);
//system.addEventReporter(new Visualizer::Reporter(viz, 1./30));
State state = system.realizeTopology();
p1.setQ(state, Vec3(.1,.2,.3));
dummy1.setAngle(state, .1);
dummy2.setAngle(state, .2);
p2.setAngle(state, .3);
p1.setU(state, Vec3(1, 2, 3));
dummy1.setRate(state, 1);
dummy2.setRate(state, 2);
p2.setRate(state, 3);
system.realize(state, Stage::Velocity);
system.project(state, 1e-10);
SimTK_TEST_EQ(c1.getBodyTransform(state), c2.getBodyTransform(state));
SimTK_TEST_EQ(c1.getBodyVelocity(state), c2.getBodyVelocity(state));
// Simulate it and see if both pendulums behave identically.
RungeKuttaMersonIntegrator integ(system);
TimeStepper ts(system, integ);
ts.initialize(state);
ts.stepTo(5);
system.realize(integ.getState(), Stage::Velocity);
SimTK_TEST_EQ_TOL(c1.getBodyTransform(integ.getState()),
c2.getBodyTransform(integ.getState()), 1e-10);
SimTK_TEST_EQ_TOL(c1.getBodyVelocity(integ.getState()),
c2.getBodyVelocity(integ.getState()), 1e-10);
}
// Create two pendulums with bushing joints, one where the bushings are faked
// with a Cartesian (3 sliders) and a series of pin joints that should provide
// identical generalized coordinates and speeds, except that the translational
// coordinates are the last three q's for the bushing but are interpreted as
// translating first, then rotating.
void testBushing() {
MultibodySystem system;
SimbodyMatterSubsystem matter(system);
GeneralForceSubsystem forces(system);
Force::UniformGravity gravity(forces, matter, Vec3(0, -9.81, 0));
Body::Rigid lumpy(MassProperties(3.1, Vec3(.1, .2, .3),
UnitInertia(1.2,1.1,1.3,.01,.02,.03)));
Body::Rigid massless(MassProperties(0,Vec3(0),UnitInertia(0)));
Vec3 inboard(0.1, 0.5, -1);
Vec3 outboard(0.2, -0.2, 0);
MobilizedBody::Bushing p1(matter.updGround(), inboard, lumpy, outboard);
Rotation axisX(Pi/2, YAxis); // rotate z into x
Rotation axisY(-Pi/2, XAxis); // rotate z into y
Rotation axisZ; // leave z where it is
MobilizedBody::Translation dummy0(matter.updGround(), inboard,
massless, Transform());
MobilizedBody::Pin dummy1(dummy0, Transform(axisX,Vec3(0)),
massless, Transform(axisX, Vec3(0)));
MobilizedBody::Pin dummy2(dummy1, Transform(axisY, Vec3(0)),
massless, Transform(axisY, Vec3(0)));
MobilizedBody::Pin p2(dummy2, Transform(axisZ, Vec3(0)),
lumpy, Transform(axisZ, outboard));
MobilizedBody::Weld c1(p1, inboard, lumpy, outboard);
MobilizedBody::Weld c2(p2, inboard, lumpy, outboard);
c1.addBodyDecoration(Transform(), DecorativeBrick(.1*Vec3(1,2,3))
.setColor(Cyan).setOpacity(0.2));
c2.addBodyDecoration(Transform(), DecorativeBrick(.1*Vec3(1,2,3))
.setColor(Red).setRepresentation(DecorativeGeometry::DrawWireframe));
//Visualizer viz(system); viz.setBackgroundType(Visualizer::SolidColor);
//system.addEventReporter(new Visualizer::Reporter(viz, 1./30));
State state = system.realizeTopology();
p1.setQ(state, Vec6(.1,.2,.3,1,2,3));
dummy0.setTranslation(state, Vec3(1,2,3));
dummy1.setAngle(state, .1);
dummy2.setAngle(state, .2);
p2.setAngle(state, .3);
p1.setU(state, Vec6(1, 2, 3, -.1, -.2, -.3));
dummy0.setVelocity(state, Vec3(-.1, -.2, -.3));
dummy1.setRate(state, 1);
dummy2.setRate(state, 2);
p2.setRate(state, 3);
system.realize(state, Stage::Velocity);
system.project(state, 1e-10);
SimTK_TEST_EQ(c1.getBodyTransform(state), c2.getBodyTransform(state));
SimTK_TEST_EQ(c1.getBodyVelocity(state), c2.getBodyVelocity(state));
// Simulate it and see if both pendulums behave identically.
RungeKuttaMersonIntegrator integ(system);
TimeStepper ts(system, integ);
ts.initialize(state);
ts.stepTo(5);
system.realize(integ.getState(), Stage::Velocity);
SimTK_TEST_EQ_TOL(c1.getBodyTransform(integ.getState()),
c2.getBodyTransform(integ.getState()), 1e-10);
SimTK_TEST_EQ_TOL(c1.getBodyVelocity(integ.getState()),
c2.getBodyVelocity(integ.getState()), 1e-10);
}
int main() {
SimTK_START_TEST("TestMobilizedBody");
SimTK_SUBTEST(testCalculationMethods);
SimTK_SUBTEST(testWeld);
SimTK_SUBTEST(testGimbal);
SimTK_SUBTEST(testBushing);
SimTK_END_TEST();
}
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