localization_monitor.cpp

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/*
 * Copyright (c) 2008, Willow Garage, Inc.
 * All rights reserved.
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 *       this software without specific prior written permission.
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#include <flirtlib_ros/localization_monitor.h>

namespace flirtlib_ros
{

namespace sm=sensor_msgs;
namespace gm=geometry_msgs;
namespace gu=occupancy_grid_utils;
namespace nm=nav_msgs;

ScanPoseEvaluator::ScanPoseEvaluator (const nm::OccupancyGrid& g,
                                      const double threshold) :
  geom_(g.info), distances_(gu::distanceField(g, threshold))
{
  ROS_INFO ("Scan pose evaluator initialized");
}

gm::Pose ScanPoseEvaluator::adjustPose (const sm::LaserScan& scan,
                                        const gm::Pose& initial_pose,
                                        const double pos_range,
                                        const double dpos,
                                        const double dtheta) const
{
  const double x0=initial_pose.position.x;
  const double y0=initial_pose.position.y;
  const double theta0 = tf::getYaw(initial_pose.orientation);
  
  double best = 1e9;
  gm::Pose best_pose;

  for (double x=x0-pos_range; x<x0+pos_range; x+=dpos)
  {
    for (double y=y0-pos_range; y<y0+pos_range; y+=dpos)
    {
      for (double th=theta0-3.14; th<theta0+3.14; th+=dtheta)
      {
        gm::Pose p;
        p.position.x = x;
        p.position.y = y;
        p.orientation = tf::createQuaternionMsgFromYaw(th);
        double badness = (*this)(scan, p);
        if (badness < best)
        {
          ROS_DEBUG_NAMED ("adjust_pose", "Badness of %.2f, %.2f, %.2f is %.2f",
                           x, y, th, badness);
          best = badness;
          best_pose = p;
        }
      }
    }
  }
  
  ROS_ASSERT(best<1e8);
  return best_pose;
}

float ScanPoseEvaluator::operator() (const sm::LaserScan& scan,
                                     const gm::Pose& pose) const
{
  // Scanner pose
  const double theta0 = tf::getYaw(pose.orientation);
  const double x0 = pose.position.x;
  const double y0 = pose.position.y;

  std::vector<double> distances;

  // Iterate over range readings, and get the coordinates of the 
  // corresponding point in the map frame for the given sensor pose
  for (size_t i=0; i<scan.ranges.size(); i++)
  {
    const double theta = theta0 + scan.angle_min + i*scan.angle_increment;
    const double r = scan.ranges[i];
    gm::Point p;
    p.x = x0 + cos(theta)*r;
    p.y = y0 + sin(theta)*r;
    p.z = 0;
    
    // Now figure out the distance to the closest obstacle in the map
    // If the point's off the map, use a large value (we're taking a median, 
    // so it doesn't matter)
    const gu::Cell c = gu::pointCell(geom_, p);
    const double d = withinBounds(geom_, c) ? distances_[c] : 1e9;
    distances.push_back(d);
  }
  
  // Return the median distance
  sort(distances.begin(), distances.end());
  const size_t mid = distances.size()/2;
  return distances[mid];
}

} // namespace