phase_spline.cc

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#include <towr/variables/phase_spline.h>
#include <towr/variables/phase_durations.h>

namespace towr {

PhaseSpline::PhaseSpline(
    PhaseNodes::Ptr const nodes,
    PhaseDurations* const phase_durations)
    : NodeSpline(nodes.get(), nodes->ConvertPhaseToPolyDurations(phase_durations->GetPhaseDurations())),
      PhaseDurationsObserver(phase_durations)
{
  phase_nodes_ = nodes;

  UpdatePolynomialDurations();

  // if durations change, the polynomial active at a specified global time
  // changes. Therefore, all elements of the Jacobian could be non-zero
  // and must make sure that Jacobian structure never changes during
  // the iterations.
  // assume every global time time can fall into every polynomial
  for (int i=0; i<nodes->GetPolynomialCount(); ++i)
    FillJacobianWrtNodes(i, 0.0, kPos, jac_wrt_nodes_structure_, true);
}

void
PhaseSpline::UpdatePolynomialDurations()
{
  auto phase_duration = phase_durations_->GetPhaseDurations();
  auto poly_durations = phase_nodes_->ConvertPhaseToPolyDurations(phase_duration);

  for (int i=0; i<cubic_polys_.size(); ++i) {
    cubic_polys_.at(i).SetDuration(poly_durations.at(i));
  }

  UpdatePolynomialCoeff();
}

PhaseSpline::Jacobian
PhaseSpline::GetJacobianOfPosWrtDurations (double t_global) const
{
  VectorXd dx_dT  = GetDerivativeOfPosWrtPhaseDuration(t_global);
  VectorXd xd     = GetPoint(t_global).v();
  int current_phase = GetSegmentID(t_global, phase_durations_->GetPhaseDurations());

  return phase_durations_->GetJacobianOfPos(current_phase, dx_dT, xd);
}

Eigen::VectorXd
PhaseSpline::GetDerivativeOfPosWrtPhaseDuration (double t_global) const
{
  int poly_id; double t_local;
  std::tie(poly_id, t_local) = GetLocalTime(t_global, GetPolyDurations());

  VectorXd vel  = GetPoint(t_global).v();
  VectorXd dxdT = cubic_polys_.at(poly_id).GetDerivativeOfPosWrtDuration(t_local);

  double inner_derivative = phase_nodes_->GetDerivativeOfPolyDurationWrtPhaseDuration(poly_id);
  double prev_polys_in_phase = phase_nodes_->GetNumberOfPrevPolynomialsInPhase(poly_id);

  // where does this minus stuff come from?
  // from number of polynomials before current polynomial that
  // cause shifting of entire spline
  return inner_derivative*(dxdT - prev_polys_in_phase*vel);
}


} /* namespace towr */