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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) 2007-12 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"
using namespace SimTK;
using namespace std;
#define ASSERT(cond) {SimTK_ASSERT_ALWAYS(cond, "Assertion failed");}
/**
* Test converting a SimbodyMatterSubsystem between quaternion and Euler angle representations.
*/
int main() {
// Build a system consisting of a chain of bodies with every possible mobilizer.
MultibodySystem mbs;
SimbodyMatterSubsystem matter(mbs);
Body::Rigid body = Body::Rigid(MassProperties(1, Vec3(0), Inertia(1)));
body.addDecoration(DecorativeSphere(.1));
Random::Uniform random(0.0, 2.0);
MobilizedBody lastBody = MobilizedBody::Pin(matter.Ground(), Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Slider(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Universal(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Cylinder(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::BendStretch(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Planar(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Gimbal(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Ball(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Translation(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Free(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::LineOrientation(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::FreeLine(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Weld(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
lastBody = MobilizedBody::Screw(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())), 0.5);
lastBody = MobilizedBody::Ellipsoid(lastBody, Transform(Vec3(0, 0, 0)), body, Transform(Vec3(random.getValue(), random.getValue(), random.getValue())));
mbs.realizeTopology();
State& s = mbs.updDefaultState();
mbs.realizeModel(s);
// Choose a random initial conformation.
for (int i = 0; i < s.getNQ(); ++i)
s.updQ()[i] = random.getValue();
mbs.realize(s, Stage::Instance);
// The only constraints are the quaternions -- normalize them.
Vector temp;
mbs.project(s, 0.01);
mbs.realize(s, Stage::Position);
// Convert to Euler angles and make sure the positions are all the same.
State euler = s;
matter.convertToEulerAngles(s, euler);
mbs.realize(euler, Stage::Position);
for (int i = 0; i < matter.getNumBodies(); ++i) {
const MobilizedBody& body = matter.getMobilizedBody(MobilizedBodyIndex(i));
Real dist = (body.getBodyOriginLocation(euler)-body.getBodyOriginLocation(s)).norm();
ASSERT(dist < 1e-5);
}
// Now convert back to quaternions and make sure the positions are still the same.
State quaternions = s;
matter.convertToQuaternions(euler, quaternions);
mbs.realize(quaternions, Stage::Position);
for (int i = 0; i < matter.getNumBodies(); ++i) {
const MobilizedBody& body = matter.getMobilizedBody(MobilizedBodyIndex(i));
Real dist = (body.getBodyOriginLocation(quaternions)-body.getBodyOriginLocation(s)).norm();
ASSERT(dist < 1e-5);
}
// Compare the state variables to see if they have been accurately reproduced.
mbs.project(s, 0.01); // Normalize the quaternions
Real diff = std::sqrt((s.getQ()-quaternions.getQ()).normSqr()/s.getNQ());
ASSERT(diff < 1e-5);
std::cout << "Done" << std::endl;
}
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