Molmodel
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00001 #ifndef SimTK_MASS_CENTER_MOTION_REMOVER_H_ 00002 #define SimTK_MASS_CENTER_MOTION_REMOVER_H_ 00003 /* -------------------------------------------------------------------------- * 00004 * SimTK Core: SimTK Simbody(tm) * 00005 * -------------------------------------------------------------------------- * 00006 * This is part of the SimTK Core biosimulation toolkit originating from * 00007 * Simbios, the NIH National Center for Physics-Based Simulation of * 00008 * Biological Structures at Stanford, funded under the NIH Roadmap for * 00009 * Medical Research, grant U54 GM072970. See https://simtk.org. * 00010 * * 00011 * Portions copyright (c) 2009 Stanford University and the Authors. * 00012 * Authors: Michael Sherman * 00013 * Contributors: * 00014 * * 00015 * Permission is hereby granted, free of charge, to any person obtaining a * 00016 * copy of this software and associated documentation files (the "Software"), * 00017 * to deal in the Software without restriction, including without limitation * 00018 * the rights to use, copy, modify, merge, publish, distribute, sublicense, * 00019 * and/or sell copies of the Software, and to permit persons to whom the * 00020 * Software is furnished to do so, subject to the following conditions: * 00021 * * 00022 * The above copyright notice and this permission notice shall be included in * 00023 * all copies or substantial portions of the Software. * 00024 * * 00025 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * 00026 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * 00027 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * 00028 * THE AUTHORS, CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * 00029 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * 00030 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE * 00031 * USE OR OTHER DEALINGS IN THE SOFTWARE. * 00032 * -------------------------------------------------------------------------- */ 00033 00034 #include "SimTKsimbody.h" 00035 #include "molmodel/internal/common.h" 00036 #include "molmodel/internal/MolecularMechanicsSystem.h" 00037 00038 namespace SimTK { 00039 00050 class MassCenterMotionRemover 00051 : public PeriodicEventHandler { 00052 public: 00069 explicit MassCenterMotionRemover(const MolecularMechanicsSystem& system, 00070 Real adjustmentInterval = 1) // ps 00071 : PeriodicEventHandler(adjustmentInterval), 00072 system(system), linearMomOnly(false), 00073 enableCOMCorrection(false), comTol(1), comPos(0) 00074 { 00075 } 00076 00088 MassCenterMotionRemover& disableAngularMomentumRemoval(bool disable) 00089 { linearMomOnly = disable; return *this; } 00095 bool isAngularMomentumRemovalDisabled() const {return linearMomOnly;} 00096 00112 MassCenterMotionRemover& enableMassCenterCorrection(bool enabled) 00113 { enableCOMCorrection = enabled; return *this; } 00119 bool isMassCenterCorrectionEnabled() const {return enableCOMCorrection;} 00120 00136 MassCenterMotionRemover& 00137 setDesiredMassCenterLocation(const Vec3& groundLocationInNm) 00138 { comPos = groundLocationInNm; return *this; } 00144 const Vec3& getDesiredMassCenterLocation() const {return comPos;} 00145 00164 MassCenterMotionRemover& 00165 setMassCenterLocationTolerance(Real toleranceInNm) { 00166 SimTK_APIARGCHECK1_ALWAYS(toleranceInNm > 0, 00167 "MassCenterMotionRemover","setMassCenterLocationTolerance", 00168 "Illegal mass center tolerance %g.", toleranceInNm); 00169 comTol = toleranceInNm; 00170 return *this; 00171 } 00177 Real getMassCenterLocationTolerance() const {return comTol;} 00178 00187 void removeSystemMomentum(State& state) const 00188 { system.removeSystemRigidBodyMomentum(state, linearMomOnly); } 00189 00199 void correctMassCenterLocation(State& state) const 00200 { system.moveSystemMassCenter(state, comPos); } 00201 00214 Real calcMassCenterError(const State& state) const 00215 { return (system.calcSystemMassCenterLocation(state) - comPos).norm(); } 00216 00217 // This is the concrete implementation of the handleEvent() virtual 00218 // method required by every EventHandler; don't call this directly, 00219 // use removeSystemMomentum() or correctMassCenterLocation() instead. 00221 void handleEvent(State& state, Real accuracy, 00222 const Vector& yWeights, const Vector& ooConstraintTols, 00223 Stage& lowestModified, bool& shouldTerminate) const 00224 { 00225 system.realize(state, Stage::Velocity); 00226 removeSystemMomentum(state); 00227 lowestModified = Stage::Velocity; // tell integrator what we changed 00228 if (enableCOMCorrection && calcMassCenterError(state) > comTol) { 00229 correctMassCenterLocation(state); 00230 lowestModified = Stage::Position; 00231 } 00232 } 00234 00235 private: 00236 const MolecularMechanicsSystem& system; 00237 bool linearMomOnly; // should we correct angular momentum? 00238 bool enableCOMCorrection; // should we relocate the COM? 00239 Real comTol; // how far to let the COM drift (nm). 00240 Vec3 comPos; // where the COM is expected to stay. 00241 }; 00242 00243 } // namespace SimTK 00244 00245 #endif // SimTK_MASS_CENTER_MOTION_REMOVER_H_