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CoordinateCouplerConstraint.cpp
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CoordinateCouplerConstraint.cpp
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/* -------------------------------------------------------------------------- *
* OpenSim: CoordinateCouplerConstraint.cpp *
* -------------------------------------------------------------------------- *
* The OpenSim API is a toolkit for musculoskeletal modeling and simulation. *
* See http://opensim.stanford.edu and the NOTICE file for more information. *
* OpenSim is developed at Stanford University and supported by the US *
* National Institutes of Health (U54 GM072970, R24 HD065690) and by DARPA *
* through the Warrior Web program. *
* *
* Copyright (c) 2005-2017 Stanford University and the Authors *
* Author(s): Ajay Seth, Frank C. Anderson *
* *
* 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. *
* -------------------------------------------------------------------------- */
//=============================================================================
// INCLUDES
//=============================================================================
#include "CoordinateCouplerConstraint.h"
#include <OpenSim/Simulation/Model/Model.h>
#include "simbody/internal/Constraint.h"
// Helper class to construct functions when user's specify a dependency as qd = f(qi)
// this function casts as C(q) = 0 = f(qi) - qd;
// Excluding this from Doxygen until it has better documentation! -Sam Hamner
/// @cond
class CompoundFunction : public SimTK::Function {
// returns f1(x[0]) - x[1];
private:
std::unique_ptr<const SimTK::Function> f1;
const double scale;
public:
CompoundFunction(const SimTK::Function *cf, double scale) : f1(cf), scale(scale) {
}
double calcValue(const SimTK::Vector& x) const override {
SimTK::Vector xf(1);
xf[0] = x[0];
return scale*f1->calcValue(xf)-x[1];
}
double calcDerivative(const std::vector<int>& derivComponents, const SimTK::Vector& x) const {
return calcDerivative(SimTK::ArrayViewConst_<int>(derivComponents),x);
}
double calcDerivative(const SimTK::Array_<int>& derivComponents, const SimTK::Vector& x) const override {
if (derivComponents.size() == 1){
if (derivComponents[0]==0){
SimTK::Vector x1(1);
x1[0] = x[0];
return scale*f1->calcDerivative(derivComponents, x1);
}
else if (derivComponents[0]==1)
return -1;
}
else if(derivComponents.size() == 2){
if (derivComponents[0]==0 && derivComponents[1] == 0){
SimTK::Vector x1(1);
x1[0] = x[0];
return scale*f1->calcDerivative(derivComponents, x1);
}
}
return 0;
}
int getArgumentSize() const override {
return 2;
}
int getMaxDerivativeOrder() const override {
return 2;
}
void setFunction(const SimTK::Function *cf) {
f1.reset(cf);
}
};
//=============================================================================
// STATICS
//=============================================================================
using namespace std;
using namespace SimTK;
using namespace OpenSim;
//=============================================================================
// CONSTRUCTOR(S) AND DESTRUCTOR
//=============================================================================
//_____________________________________________________________________________
/**
* Destructor.
*/
CoordinateCouplerConstraint::~CoordinateCouplerConstraint()
{
}
//_____________________________________________________________________________
/**
* Default constructor.
*/
CoordinateCouplerConstraint::CoordinateCouplerConstraint() :
Constraint()
{
setNull();
constructProperties();
}
//=============================================================================
// CONSTRUCTION
//=============================================================================
//_____________________________________________________________________________
/**
* Set the data members of this CoordinateCouplerConstraint to their null values.
*/
void CoordinateCouplerConstraint::setNull()
{
setAuthors("Ajay Seth");
}
//_____________________________________________________________________________
/**
* Connect properties to local pointers.
*/
void CoordinateCouplerConstraint::constructProperties()
{
// Coordinate Coupler Function
constructProperty_coupled_coordinates_function();
// coordinates that are coupled (by name)
constructProperty_independent_coordinate_names();
// coordinates that are coupled (by name)
constructProperty_dependent_coordinate_name("");
// scale factor
constructProperty_scale_factor(1.0);
}
//_____________________________________________________________________________
/**
* Perform some set up functions that happen after the
* object has been deserialized or copied.
*
* @param aModel OpenSim Model containing this CoordinateCouplerConstraint.
*/
void CoordinateCouplerConstraint::extendConnectToModel(Model& aModel)
{
Super::extendConnectToModel(aModel);
string errorMessage;
// Look up the bodies and coordinates being coupled by name in the
// model and keep lists of their indices
Array<std::string> independentCoordNames;
for(int i = 0; i < getProperty_independent_coordinate_names().size(); i++) {
independentCoordNames.append(get_independent_coordinate_names(i));
}
for(int i=0; i<independentCoordNames.getSize(); i++){
if (!getModel().getCoordinateSet().contains(independentCoordNames[i])) {
errorMessage = "Coordinate coupler: unknown independent coordinate " ;
errorMessage += independentCoordNames[i];
throw (Exception(errorMessage));
}
}
// Last coordinate in the coupler is the dependent coordinate
if (!getModel().getCoordinateSet().contains(get_dependent_coordinate_name())) {
errorMessage = "Coordinate coupler: unknown dependent coordinate " ;
errorMessage += get_dependent_coordinate_name();
throw (Exception(errorMessage));
}
}
void CoordinateCouplerConstraint::extendAddToSystem(SimTK::MultibodySystem& system) const
{
Super::extendAddToSystem(system);
/** List of mobilized body indices established when constraint is set up */
std::vector<SimTK::MobilizedBodyIndex> mob_bodies;
/** List of coordinate (Q) indices corresponding to the respective body */
std::vector<SimTK::MobilizerQIndex> mob_qs;
string errorMessage;
// Look up the bodies and coordinates being coupled by name in the
// model and keep lists of their indices
Array<std::string> independentCoordNames;
for(int i = 0; i < getProperty_independent_coordinate_names().size(); i++) {
independentCoordNames.append(get_independent_coordinate_names(i));
}
for(int i=0; i<independentCoordNames.getSize(); i++){
// Error checking was handled in extendConnectToModel()
const Coordinate& aCoordinate = getModel().getCoordinateSet().get(independentCoordNames[i]);
mob_bodies.push_back(aCoordinate._bodyIndex);
mob_qs.push_back(SimTK::MobilizerQIndex(aCoordinate._mobilizerQIndex));
}
// Last coordinate in the coupler is the dependent coordinate
const Coordinate& aCoordinate = getModel().getCoordinateSet().get(get_dependent_coordinate_name());
mob_bodies.push_back(aCoordinate._bodyIndex);
mob_qs.push_back(SimTK::MobilizerQIndex(aCoordinate._mobilizerQIndex));
if (!mob_qs.size() & (mob_qs.size() != mob_bodies.size())) {
errorMessage = "CoordinateCouplerConstraint:: requires at least one body and coordinate." ;
throw (Exception(errorMessage));
}
// Create and set the underlying coupler constraint function;
const Function& f = getFunction();
SimTK::Function *simtkCouplerFunction = new CompoundFunction(f.createSimTKFunction(), get_scale_factor());
// Now create a Simbody Constraint::CoordinateCoupler
SimTK::Constraint::CoordinateCoupler simtkCoordinateCoupler(system.updMatterSubsystem() ,
simtkCouplerFunction,
mob_bodies, mob_qs);
// Beyond the const Component get the index so we can access the SimTK::Constraint later
assignConstraintIndex(simtkCoordinateCoupler.getConstraintIndex());
}
//==============================================================================
// SCALE
//==============================================================================
void CoordinateCouplerConstraint::
extendScale(const SimTK::State& s, const ScaleSet& scaleSet)
{
Super::extendScale(s, scaleSet);
Coordinate& depCoordinate =
_model->updCoordinateSet().get(get_dependent_coordinate_name());
// Only scale if the dependent coordinate is a translation.
if (depCoordinate.getMotionType() != Coordinate::Translational)
return;
// Get scale factors (if there exists an entry for the base Body of the
// Joint's parent Frame).
const Vec3& scaleFactors =
getScaleFactors(scaleSet, depCoordinate.getJoint().getParentFrame());
if (scaleFactors == ModelComponent::InvalidScaleFactors)
return;
// Constraint scale factor. Assume uniform scaling unless proven otherwise.
const double scaleFactor = scaleFactors[0];
// We can handle non-uniform scaling along transform axes of custom joints
// ONLY at this time.
const Joint *joint = dynamic_cast<const Joint*>(depCoordinate._joint.get());
if (joint) {
if (scaleFactors[0] != scaleFactors[1] ||
scaleFactors[0] != scaleFactors[2] )
{
// TODO: Non-uniform scaling remains undefined! - ASeth
throw(Exception("Non-uniform scaling of CoordinateCoupler constraints not implemented."));
}
}
upd_scale_factor() *= scaleFactor;
}