ConstraintSet.cpp

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/* SPDX-FileCopyrightText: 2009 Ruben Smits
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later */

 
#include "ConstraintSet.hpp"
#include "kdl/utilities/svd_eigen_HH.hpp"
 
namespace iTaSC {
 
ConstraintSet::ConstraintSet(unsigned int _nc,double accuracy,unsigned int maximum_iterations):
    m_nc(_nc),
    m_Cf(e_zero_matrix(m_nc,6)),
    m_Wy(e_scalar_vector(m_nc,1.0)),
    m_y(m_nc),m_ydot(e_zero_vector(m_nc)),m_chi(e_zero_vector(6)),
    m_S(6),m_temp(6),m_tdelta(6),
    m_Jf(e_identity_matrix(6,6)),
    m_U(e_identity_matrix(6,6)),m_V(e_identity_matrix(6,6)),m_B(e_zero_matrix(6,6)),
    m_Jf_inv(e_zero_matrix(6,6)),
    m_internalPose(F_identity), m_externalPose(F_identity),
    m_constraintCallback(NULL), m_constraintParam(NULL), 
    m_toggle(false),m_substep(false),
    m_threshold(accuracy),m_maxIter(maximum_iterations)
{
    m_maxDeltaChi = e_scalar(0.52);
}
 
ConstraintSet::ConstraintSet():
    m_nc(0), 
    m_internalPose(F_identity), m_externalPose(F_identity),
    m_constraintCallback(NULL), m_constraintParam(NULL), 
    m_toggle(false),m_substep(false),
    m_threshold(0.0),m_maxIter(0)
{
    m_maxDeltaChi = e_scalar(0.52);
}
 
void ConstraintSet::reset(unsigned int _nc,double accuracy,unsigned int maximum_iterations)
{
    m_nc = _nc;
    m_Jf = e_identity_matrix(6,6);
    m_Cf = e_zero_matrix(m_nc,6);
    m_U = e_identity_matrix(6,6);
    m_V = e_identity_matrix(6,6);
    m_B = e_zero_matrix(6,6);
    m_Jf_inv = e_zero_matrix(6,6),
    m_Wy = e_scalar_vector(m_nc,1.0),
    m_chi = e_zero_vector(6);
    m_chidot = e_zero_vector(6);
    m_y = e_zero_vector(m_nc);
    m_ydot = e_zero_vector(m_nc);
    m_S = e_zero_vector(6);
    m_temp = e_zero_vector(6);
    m_tdelta = e_zero_vector(6);
    m_threshold = accuracy;
    m_maxIter = maximum_iterations;
}
 
ConstraintSet::~ConstraintSet() {
 
}
 
void ConstraintSet::modelUpdate(Frame& _external_pose,const Timestamp& timestamp)
{
    m_chi+=m_chidot*timestamp.realTimestep;
    m_externalPose = _external_pose;
 
    //update the internal pose and Jf
    updateJacobian();
    //check if loop is already closed, if not update the pose and Jf
    unsigned int iter=0;
    while(iter<5&&!closeLoop())
        iter++;
}
 
double ConstraintSet::getMaxTimestep(double& timestep)
{
    e_scalar maxChidot = m_chidot.array().abs().maxCoeff();
    if (timestep*maxChidot > m_maxDeltaChi) {
        timestep = m_maxDeltaChi/maxChidot;
    }
    return timestep;
}
 
bool ConstraintSet::initialise(Frame& init_pose){
    m_externalPose=init_pose;
    // get current Jf
    updateJacobian();
 
    unsigned int iter=0;
    while(iter<m_maxIter&&!closeLoop()){
        iter++;
    }
    if (iter<m_maxIter)
        return true;
    else
        return false;
}
 
bool ConstraintSet::setControlParameter(int id, ConstraintAction action, double data, double timestep)
{
    ConstraintValues values;
    ConstraintSingleValue value;
    values.values = &value;
    values.number = 0;
    values.action = action;
    values.id = id;
    value.action = action;
    value.id = id;
    switch (action) {
    case ACT_NONE:
        return true;
    case ACT_VALUE:
        value.yd = data;
        values.number = 1;
        break;
    case ACT_VELOCITY:
        value.yddot = data;
        values.number = 1;
        break;
    case ACT_TOLERANCE:
        values.tolerance = data;
        break;
    case ACT_FEEDBACK:
        values.feedback = data;
        break;
    case ACT_ALPHA:
        values.alpha = data;
        break;
    default:
        assert(action==ACT_NONE);
        break;
    }
    return setControlParameters(&values, 1, timestep);
}
 
bool ConstraintSet::closeLoop(){
    //Invert Jf
    //TODO: svd_boost_Macie has problems if Jf contains zero-rows
    //toggle=!toggle;
    //svd_boost_Macie(Jf,U,S,V,B,temp,1e-3*threshold,toggle);
    int ret = KDL::svd_eigen_HH(m_Jf,m_U,m_S,m_V,m_temp);
    if(ret<0)
        return false;
 
    // the reference point and frame of the jacobian is the base frame
    // m_externalPose-m_internalPose is the twist to extend the end effector
    // to get the required pose => change the reference point to the base frame
    Twist twist_delta(diff(m_internalPose,m_externalPose));
    twist_delta=twist_delta.RefPoint(-m_internalPose.p);
    for(unsigned int i=0;i<6;i++)
        m_tdelta(i)=twist_delta(i);
    //TODO: use damping in constraintset inversion?
    for(unsigned int i=0;i<6;i++) {
        if(m_S(i)<m_threshold){
            m_B.row(i).setConstant(0.0);
        } else {
            m_B.row(i) = m_U.col(i)/m_S(i);
        }
    }
 
    m_Jf_inv.noalias()=m_V*m_B;
 
    m_chi.noalias()+=m_Jf_inv*m_tdelta;
    updateJacobian();
    // m_externalPose-m_internalPose in end effector frame
    // this is just to compare the pose, a different formula would work too
    return Equal(m_internalPose.Inverse()*m_externalPose,F_identity,m_threshold);
 
}
}