filter_functions.hpp

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#pragma once
 
#include <Eigen/Geometry>
#include <moveit/robot_model/joint_model_group.h>
#include <stomp_moveit/stomp_moveit_task.hpp>
 
#include <stomp/utils.h>
 
namespace stomp_moveit
{
namespace filters
{
// \brief An empty placeholder filter that doesn't apply any updates to the trajectory.
static const FilterFn NO_FILTER = [](const Eigen::MatrixXd& /*values*/, Eigen::MatrixXd& /*filtered_values*/) {
  return true;
};
 
FilterFn simpleSmoothingMatrix(size_t num_timesteps)
{
  // Generates a smoothing matrix and applies it for each joint dimension in filtered_values
  // The 'dt' value is a placeholder timestep duration that is used for approximating the second order derivative
  // (acceleration) using a finite difference matrix. The actual timestep duration will be computed by a planner
  // adapter after solving the STOMP trajectory.
  Eigen::MatrixXd smoothing_matrix;
  stomp::generateSmoothingMatrix(num_timesteps, 1.0 /* dt */, smoothing_matrix);
  return [=](const Eigen::MatrixXd& /*values*/, Eigen::MatrixXd& filtered_values) {
    for (auto row : filtered_values.rowwise())
    {
      row.transpose() = smoothing_matrix * row.transpose();
    }
    return true;
  };
}
 
FilterFn enforcePositionBounds(const moveit::core::JointModelGroup* group)
{
  return [=](const Eigen::MatrixXd& values, Eigen::MatrixXd& filtered_values) {
    filtered_values = values;
    const auto& joints = group->getActiveJointModels();
    for (size_t i = 0; i < joints.size(); ++i)
    {
      for (int j = 0; j < filtered_values.cols(); ++j)
      {
        joints.at(i)->enforcePositionBounds(&filtered_values.coeffRef(i, j));
      }
    }
    return true;
  };
}
 
FilterFn chain(const std::vector<FilterFn>& filter_functions)
{
  return [=](const Eigen::MatrixXd& values, Eigen::MatrixXd& filtered_values) {
    Eigen::MatrixXd values_in = values;
    for (const auto& filter_fn : filter_functions)
    {
      filter_fn(values_in, filtered_values);
      values_in = filtered_values;
    }
    return true;
  };
}
}  // namespace filters
}  // namespace stomp_moveit