fritsch_butland_spline_smoother.h

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#ifndef FRITSCH_BUTLAND_SPLINE_SMOOTHER_H_
#define FRITSCH_BUTLAND_SPLINE_SMOOTHER_H_

#include <spline_smoother/spline_smoother.h>

namespace spline_smoother
{

template <typename T>
class FritschButlandSplineSmoother: public SplineSmoother<T>
{
public:
  FritschButlandSplineSmoother();
  virtual ~FritschButlandSplineSmoother();

  virtual bool smooth(const T& trajectory_in, 
                      T& trajectory_out) const;
};

template <typename T>
FritschButlandSplineSmoother<T>::FritschButlandSplineSmoother()
{
}

template <typename T>
FritschButlandSplineSmoother<T>::~FritschButlandSplineSmoother()
{
}

template <typename T>
bool FritschButlandSplineSmoother<T>::smooth(const T& trajectory_in, 
                                          T& trajectory_out) const
{
  bool success = true;

  int size = trajectory_in.request.trajectory.points.size();
  int num_traj = trajectory_in.request.trajectory.joint_names.size();
  trajectory_out = trajectory_in;

  if (!checkTrajectoryConsistency(trajectory_out))
    return false;

  // keep the first and last velocities intact

  // for every point in time:
  for (int i=1; i<size-1; ++i)
  {
    double h1 = (trajectory_in.request.trajectory.points[i].time_from_start - trajectory_in.request.trajectory.points[i-1].time_from_start).toSec();
    double h2 = (trajectory_in.request.trajectory.points[i+1].time_from_start - trajectory_in.request.trajectory.points[i].time_from_start).toSec();

    // for every (joint) trajectory
    for (int j=0; j<num_traj; ++j)
    {
      double s1 = (trajectory_in.request.trajectory.points[i].positions[j] - trajectory_in.request.trajectory.points[i-1].positions[j])/h1;
      double s2 = (trajectory_in.request.trajectory.points[i+1].positions[j] - trajectory_in.request.trajectory.points[i].positions[j])/h2;

      double alpha = (1 + h2/(h1+h2))/3.0;

      double vel = 0.0;
      if (s1*s2 > 0)
      {
        vel = (s1*s2)/(alpha*s2 + (1.0-alpha)*s1);
      }
      trajectory_out.request.trajectory.points[i].velocities[j] = vel;
      trajectory_out.request.trajectory.points[i].accelerations[j] = 0.0;
    }
  }
  return success;
}
}

#endif /* FRITSCH_BUTLAND_SPLINE_SMOOTHER_H_ */