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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) 2011-12 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 "SimTKsimbody.h"
#include "SimTKcommon/Testing.h"
#include <vector>
#include <map>
using namespace SimTK;
using namespace std;
const Real TOL = 1e-10;
#define ASSERT(cond) {SimTK_ASSERT_ALWAYS(cond, "Assertion failed");}
template <class T>
void assertEqual(T val1, T val2) {
ASSERT(abs(val1-val2) < TOL);
}
template <int N>
void assertEqual(Vec<N> val1, Vec<N> val2) {
for (int i = 0; i < N; ++i)
ASSERT(abs(val1[i]-val2[i]) < TOL);
}
static void compareToTranslate(bool prescribe, Motion::Level level) {
// Create a system of pairs of identical bodies, where half will be implemented with RBNodeLoneParticle
// and half with RBNodeTranslate.
MultibodySystem system;
SimbodyMatterSubsystem matter(system);
GeneralForceSubsystem force(system);
Force::UniformGravity gravity(force, matter, Vec3(1.1, 1.2, 1.3));
Body::Rigid body(MassProperties(1.0, Vec3(0), Inertia(1)));
Random::Gaussian random(0.0, 3.0);
const int numBodies = 10;
for (int i = 0; i < numBodies; i++) {
MobilizedBody::Translation body1(matter.updGround(), body);
MobilizedBody::Translation body2(matter.updGround(), Vec3(0), body, Vec3(1e-100));
Vec3 station1(random.getValue(), random.getValue(), random.getValue());
Vec3 station2(random.getValue(), random.getValue(), random.getValue());
Real length = random.getValue();
Force::TwoPointLinearSpring(force, matter.updGround(), station1, body1, station2, 1.0, length);
Force::TwoPointLinearSpring(force, matter.updGround(), station1, body2, station2, 1.0, length);
if (prescribe) {
Real phase = random.getValue();
Motion::Sinusoid(body1, level, 1.5, 1.1, phase);
Motion::Sinusoid(body2, level, 1.5, 1.1, phase);
}
}
// Initialize the state.
State state = system.realizeTopology();
for (int i = 0; i < numBodies; i++) {
Vec3 pos(random.getValue(), random.getValue(), random.getValue());
Vec3 vel(random.getValue(), random.getValue(), random.getValue());
const MobilizedBody& body1 = matter.getMobilizedBody(MobilizedBodyIndex(2*i+1));
const MobilizedBody& body2 = matter.getMobilizedBody(MobilizedBodyIndex(2*i+2));
body1.setQToFitTranslation(state, pos);
body2.setQToFitTranslation(state, pos);
body1.setUToFitLinearVelocity(state, vel);
body2.setUToFitLinearVelocity(state, vel);
}
// Calculate lots of quantities from the MobilizedBodies.
system.realize(state, Stage::Acceleration);
Vector_<SpatialVec> reactionForces;
matter.calcMobilizerReactionForces(state, reactionForces);
Vector_<SpatialVec> reactionForcesFreebody;
matter.calcMobilizerReactionForcesUsingFreebodyMethod(state, reactionForcesFreebody);
// Both methods should produce the same results.
SimTK_TEST_EQ(reactionForces, reactionForcesFreebody);
Vector mv, minvv;
matter.multiplyByM(state, state.getU(), mv);
matter.multiplyByMInv(state, state.getU(), minvv);
Vector appliedMobilityForces(matter.getNumMobilities());
Vector_<SpatialVec> appliedBodyForces(matter.getNumBodies());
for (int i = 0; i < numBodies; i++) {
Vec3 mobilityForce;
random.fillArray((Real*) &mobilityForce, 3);
Vec3::updAs(&appliedMobilityForces[6*i]) = mobilityForce;
Vec3::updAs(&appliedMobilityForces[6*i+3]) = mobilityForce;
SpatialVec bodyForce;
random.fillArray((Real*) &bodyForce, 6);
appliedBodyForces[2*i+1] = bodyForce;
appliedBodyForces[2*i+2] = bodyForce;
}
Vector knownUdot, residualMobilityForces;
matter.calcResidualForceIgnoringConstraints(state, appliedMobilityForces, appliedBodyForces, knownUdot, residualMobilityForces);
Vector dEdQ;
matter.multiplyBySystemJacobianTranspose(state, appliedBodyForces, dEdQ);
Array_<SpatialInertia,MobilizedBodyIndex> compositeInertias;
matter.calcCompositeBodyInertias(state, compositeInertias);
// See whether the RBNodeLoneParticles and the RBNodeTranslates produced identical results.
for (int i = 0; i < numBodies; i++) {
MobilizedBodyIndex index1(2*i+1);
MobilizedBodyIndex index2(2*i+2);
const MobilizedBody& body1 = matter.getMobilizedBody(index1);
const MobilizedBody& body2 = matter.getMobilizedBody(index2);
assertEqual(body1.getBodyOriginLocation(state), body2.getBodyOriginLocation(state));
assertEqual(body1.getBodyOriginVelocity(state), body2.getBodyOriginVelocity(state));
assertEqual(body1.getBodyOriginAcceleration(state), body2.getBodyOriginAcceleration(state));
assertEqual(reactionForces[index1][0], reactionForces[index2][0]);
assertEqual(reactionForces[index1][1], reactionForces[index2][1]);
assertEqual(Vec3::getAs(&mv[6*i]), Vec3::getAs(&mv[6*i+3]));
if (!prescribe)
assertEqual(Vec3::getAs(&minvv[6*i]), Vec3::getAs(&minvv[6*i+3]));
assertEqual(Vec3::getAs(&residualMobilityForces[6*i]), Vec3::getAs(&residualMobilityForces[6*i+3]));
assertEqual(Vec3::getAs(&dEdQ[6*i]), Vec3::getAs(&dEdQ[6*i+3]));
assertEqual(compositeInertias[index1].getMass(), compositeInertias[index2].getMass());
assertEqual(compositeInertias[index1].getMassCenter(), compositeInertias[index2].getMassCenter());
assertEqual(compositeInertias[index1].getUnitInertia().getMoments(), compositeInertias[index2].getUnitInertia().getMoments());
assertEqual(compositeInertias[index1].getUnitInertia().getProducts(), compositeInertias[index2].getUnitInertia().getProducts());
}
}
static void testFree() {
compareToTranslate(false, Motion::Position);
}
static void testPrescribePosition() {
compareToTranslate(true, Motion::Position);
}
static void testPrescribeVelocity() {
compareToTranslate(true, Motion::Velocity);
}
static void testPrescribeAcceleration() {
compareToTranslate(true, Motion::Acceleration);
}
int main() {
SimTK_START_TEST("TestLoneParticle");
SimTK_SUBTEST(testFree);
SimTK_SUBTEST(testPrescribePosition);
SimTK_SUBTEST(testPrescribeVelocity);
SimTK_SUBTEST(testPrescribeAcceleration);
SimTK_END_TEST();
}
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