obstacle_footprint.cpp

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#include "dwb_critics/obstacle_footprint.hpp"
#include <algorithm>
#include <vector>
#include "dwb_critics/line_iterator.hpp"
#include "dwb_core/exceptions.hpp"
#include "pluginlib/class_list_macros.hpp"
#include "nav2_costmap_2d/cost_values.hpp"
 
PLUGINLIB_EXPORT_CLASS(dwb_critics::ObstacleFootprintCritic, dwb_core::TrajectoryCritic)
 
namespace dwb_critics
{
Footprint getOrientedFootprint(
  const geometry_msgs::msg::Pose & pose,
  const Footprint & footprint_spec)
{
  std::vector<geometry_msgs::msg::Point> oriented_footprint;
  oriented_footprint.resize(footprint_spec.size());
  double theta = tf2::getYaw(pose.orientation);
  double cos_th = cos(theta);
  double sin_th = sin(theta);
  for (unsigned int i = 0; i < footprint_spec.size(); ++i) {
    geometry_msgs::msg::Point & new_pt = oriented_footprint[i];
    new_pt.x = pose.position.x + footprint_spec[i].x * cos_th - footprint_spec[i].y * sin_th;
    new_pt.y = pose.position.y + footprint_spec[i].x * sin_th + footprint_spec[i].y * cos_th;
  }
  return oriented_footprint;
}
 
bool ObstacleFootprintCritic::prepare(
  const geometry_msgs::msg::Pose &, const nav_2d_msgs::msg::Twist2D &,
  const geometry_msgs::msg::Pose &, const nav_msgs::msg::Path &)
{
  footprint_spec_ = costmap_ros_->getRobotFootprint();
  if (footprint_spec_.size() == 0) {
    RCLCPP_ERROR(
      rclcpp::get_logger("ObstacleFootprintCritic"),
      "Footprint spec is empty, maybe missing call to setFootprint?");
    return false;
  }
  return true;
}
 
double ObstacleFootprintCritic::scorePose(const geometry_msgs::msg::Pose & pose)
{
  unsigned int cell_x, cell_y;
  if (!costmap_->worldToMap(pose.position.x, pose.position.y, cell_x, cell_y)) {
    throw dwb_core::
          IllegalTrajectoryException(name_, "Trajectory Goes Off Grid.");
  }
  return scorePose(pose, getOrientedFootprint(pose, footprint_spec_));
}
 
double ObstacleFootprintCritic::scorePose(
  const geometry_msgs::msg::Pose &,
  const Footprint & footprint)
{
  // now we really have to lay down the footprint in the costmap grid
  unsigned int x0, x1, y0, y1;
  double line_cost = 0.0;
  double footprint_cost = 0.0;
 
  // we need to rasterize each line in the footprint
  for (unsigned int i = 0; i < footprint.size() - 1; ++i) {
    // get the cell coord of the first point
    if (!costmap_->worldToMap(footprint[i].x, footprint[i].y, x0, y0)) {
      throw dwb_core::
            IllegalTrajectoryException(name_, "Footprint Goes Off Grid.");
    }
 
    // get the cell coord of the second point
    if (!costmap_->worldToMap(footprint[i + 1].x, footprint[i + 1].y, x1, y1)) {
      throw dwb_core::
            IllegalTrajectoryException(name_, "Footprint Goes Off Grid.");
    }
 
    line_cost = lineCost(x0, x1, y0, y1);
    footprint_cost = std::max(line_cost, footprint_cost);
  }
 
  // we also need to connect the first point in the footprint to the last point
  // get the cell coord of the last point
  if (!costmap_->worldToMap(footprint.back().x, footprint.back().y, x0, y0)) {
    throw dwb_core::
          IllegalTrajectoryException(name_, "Footprint Goes Off Grid.");
  }
 
  // get the cell coord of the first point
  if (!costmap_->worldToMap(footprint.front().x, footprint.front().y, x1, y1)) {
    throw dwb_core::
          IllegalTrajectoryException(name_, "Footprint Goes Off Grid.");
  }
 
  line_cost = lineCost(x0, x1, y0, y1);
  footprint_cost = std::max(line_cost, footprint_cost);
 
  // if all line costs are legal... then we can return that the footprint is legal
  return footprint_cost;
}
 
double ObstacleFootprintCritic::lineCost(int x0, int x1, int y0, int y1)
{
  double line_cost = 0.0;
  double point_cost = -1.0;
 
  for (LineIterator line(x0, y0, x1, y1); line.isValid(); line.advance()) {
    point_cost = pointCost(line.getX(), line.getY());   // Score the current point
 
    if (line_cost < point_cost) {
      line_cost = point_cost;
    }
  }
 
  return line_cost;
}
 
double ObstacleFootprintCritic::pointCost(int x, int y)
{
  unsigned char cost = costmap_->getCost(x, y);
  // if the cell is in an obstacle the path is invalid or unknown
  if (cost == nav2_costmap_2d::LETHAL_OBSTACLE) {
    throw dwb_core::
          IllegalTrajectoryException(name_, "Trajectory Hits Obstacle.");
  } else if (cost == nav2_costmap_2d::NO_INFORMATION) {
    throw dwb_core::
          IllegalTrajectoryException(name_, "Trajectory Hits Unknown Region.");
  }
 
  return cost;
}
 
}  // namespace dwb_critics