range_sensor_layer.cpp

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// Copyright 2018 David V. Lu!!
#include <range_sensor_layer/range_sensor_layer.h>
#include <boost/algorithm/string.hpp>
#include <geometry_msgs/PointStamped.h>
#include <pluginlib/class_list_macros.h>
#include <angles/angles.h>
#include <algorithm>
#include <list>
#include <limits>
#include <map>
#include <string>
#include <utility>

PLUGINLIB_EXPORT_CLASS(range_sensor_layer::RangeSensorLayer, costmap_2d::Layer)

using costmap_2d::NO_INFORMATION;

namespace range_sensor_layer
{

RangeSensorLayer::RangeSensorLayer() {}

void RangeSensorLayer::onInitialize()
{
  ros::NodeHandle nh("~/" + name_);
  current_ = true;
  buffered_readings_ = 0;
  last_reading_time_ = ros::Time::now();
  default_value_ = to_cost(0.5);

  matchSize();
  resetRange();

  // Default topic names list contains a single topic: /sonar
  // We use the XmlRpcValue constructor that takes a XML string and reading start offset
  const char* xml = "<value><array><data><value>/sonar</value></data></array></value>";
  int zero_offset = 0;
  std::string topics_ns;
  XmlRpc::XmlRpcValue topic_names(xml, &zero_offset);

  nh.param("ns", topics_ns, std::string());
  nh.param("topics", topic_names, topic_names);

  InputSensorType input_sensor_type = ALL;
  std::string sensor_type_name;
  nh.param("input_sensor_type", sensor_type_name, std::string("ALL"));

  nh.param("use_decay", use_decay_, false);
  nh.param("pixel_decay", pixel_decay_, 10.0);
  nh.param("transform_tolerance_", transform_tolerance_, 0.3);

  boost::to_upper(sensor_type_name);
  ROS_INFO("%s: %s as input_sensor_type given", name_.c_str(), sensor_type_name.c_str());

  if (sensor_type_name == "VARIABLE")
    input_sensor_type = VARIABLE;
  else if (sensor_type_name == "FIXED")
    input_sensor_type = FIXED;
  else if (sensor_type_name == "ALL")
    input_sensor_type = ALL;
  else
  {
    ROS_ERROR("%s: Invalid input sensor type: %s", name_.c_str(), sensor_type_name.c_str());
  }

  // Validate topic names list: it must be a (normally non-empty) list of strings
  if ((topic_names.valid() == false) || (topic_names.getType() != XmlRpc::XmlRpcValue::TypeArray))
  {
    ROS_ERROR("Invalid topic names list: it must be a non-empty list of strings");
    return;
  }

  if (topic_names.size() < 1)
  {
    // This could be an error, but I keep it as it can be useful for debug
    ROS_WARN("Empty topic names list: range sensor layer will have no effect on costmap");
  }

  // Traverse the topic names list subscribing to all of them with the same callback method
  for (int i = 0; i < topic_names.size(); i++)
  {
    if (topic_names[i].getType() != XmlRpc::XmlRpcValue::TypeString)
    {
      ROS_WARN("Invalid topic names list: element %d is not a string, so it will be ignored", i);
    }
    else
    {
      std::string topic_name(topics_ns);
      if ((topic_name.size() > 0) && (topic_name.at(topic_name.size() - 1) != '/'))
        topic_name += "/";
      topic_name += static_cast<std::string>(topic_names[i]);

      if (input_sensor_type == VARIABLE)
        processRangeMessageFunc_ = boost::bind(&RangeSensorLayer::processVariableRangeMsg, this, _1);
      else if (input_sensor_type == FIXED)
        processRangeMessageFunc_ = boost::bind(&RangeSensorLayer::processFixedRangeMsg, this, _1);
      else if (input_sensor_type == ALL)
        processRangeMessageFunc_ = boost::bind(&RangeSensorLayer::processRangeMsg, this, _1);
      else
      {
        ROS_ERROR(
          "%s: Invalid input sensor type: %s. Did you make a new type and forgot to choose the subscriber for it?",
          name_.c_str(), sensor_type_name.c_str());
      }

      range_subs_.push_back(nh.subscribe(topic_name, 100, &RangeSensorLayer::bufferIncomingRangeMsg, this));

      ROS_INFO("RangeSensorLayer: subscribed to topic %s", range_subs_.back().getTopic().c_str());
    }
  }

  dsrv_ = new dynamic_reconfigure::Server<range_sensor_layer::RangeSensorLayerConfig>(nh);
  dynamic_reconfigure::Server<range_sensor_layer::RangeSensorLayerConfig>::CallbackType cb =
    boost::bind(&RangeSensorLayer::reconfigureCB, this, _1, _2);
  dsrv_->setCallback(cb);
  global_frame_ = layered_costmap_->getGlobalFrameID();
}


double RangeSensorLayer::gamma(double theta)
{
  if (fabs(theta) > max_angle_)
    return 0.0;
  else
    return 1 - pow(theta / max_angle_, 2);
}

double RangeSensorLayer::delta(double phi)
{
  return 1 - (1 + tanh(2 * (phi - phi_v_))) / 2;
}

void RangeSensorLayer::get_deltas(double angle, double *dx, double *dy)
{
  double ta = tan(angle);
  if (ta == 0)
    *dx = 0;
  else
    *dx = resolution_ / ta;

  *dx = copysign(*dx, cos(angle));
  *dy = copysign(resolution_, sin(angle));
}

double RangeSensorLayer::sensor_model(double r, double phi, double theta)
{
  double lbda = delta(phi) * gamma(theta);

  double delta = resolution_;

  if (phi >= 0.0 && phi < r - 2 * delta * r)
    return (1 - lbda) * (0.5);
  else if (phi < r - delta * r)
    return lbda * 0.5 * pow((phi - (r - 2 * delta * r)) / (delta * r), 2) + (1 - lbda) * .5;
  else if (phi < r + delta * r)
  {
    double J = (r - phi) / (delta * r);
    return lbda * ((1 - (0.5) * pow(J, 2)) - 0.5) + 0.5;
  }
  else
    return 0.5;
}


void RangeSensorLayer::reconfigureCB(range_sensor_layer::RangeSensorLayerConfig &config, uint32_t level)
{
  phi_v_ = config.phi;
  inflate_cone_ = config.inflate_cone;
  no_readings_timeout_ = config.no_readings_timeout;
  clear_threshold_ = config.clear_threshold;
  mark_threshold_ = config.mark_threshold;
  clear_on_max_reading_ = config.clear_on_max_reading;

  if (enabled_ != config.enabled)
  {
    enabled_ = config.enabled;
    current_ = false;
  }
}

void RangeSensorLayer::bufferIncomingRangeMsg(const sensor_msgs::RangeConstPtr& range_message)
{
  boost::mutex::scoped_lock lock(range_message_mutex_);
  range_msgs_buffer_.push_back(*range_message);
}

void RangeSensorLayer::updateCostmap()
{
  std::list<sensor_msgs::Range> range_msgs_buffer_copy;

  range_message_mutex_.lock();
  range_msgs_buffer_copy = std::list<sensor_msgs::Range>(range_msgs_buffer_);
  range_msgs_buffer_.clear();
  range_message_mutex_.unlock();

  for (std::list<sensor_msgs::Range>::iterator range_msgs_it = range_msgs_buffer_copy.begin();
       range_msgs_it != range_msgs_buffer_copy.end(); range_msgs_it++)
  {
    processRangeMessageFunc_(*range_msgs_it);
  }
}

void RangeSensorLayer::processRangeMsg(sensor_msgs::Range& range_message)
{
  if (range_message.min_range == range_message.max_range)
    processFixedRangeMsg(range_message);
  else
    processVariableRangeMsg(range_message);
}

void RangeSensorLayer::processFixedRangeMsg(sensor_msgs::Range& range_message)
{
  if (!std::isinf(range_message.range))
  {
    ROS_ERROR_THROTTLE(1.0,
                       "Fixed distance ranger (min_range == max_range) in frame %s sent invalid value. "
                       "Only -Inf (== object detected) and Inf (== no object detected) are valid.",
                       range_message.header.frame_id.c_str());
    return;
  }

  bool clear_sensor_cone = false;

  if (range_message.range > 0)  // +inf
  {
    if (!clear_on_max_reading_)
      return;  // no clearing at all

    clear_sensor_cone = true;
  }

  range_message.range = range_message.min_range;

  updateCostmap(range_message, clear_sensor_cone);
}

void RangeSensorLayer::processVariableRangeMsg(sensor_msgs::Range& range_message)
{
  if (range_message.range < range_message.min_range || range_message.range > range_message.max_range)
    return;

  bool clear_sensor_cone = false;

  if (range_message.range == range_message.max_range && clear_on_max_reading_)
    clear_sensor_cone = true;

  updateCostmap(range_message, clear_sensor_cone);
}

void RangeSensorLayer::updateCostmap(sensor_msgs::Range& range_message, bool clear_sensor_cone)
{
  max_angle_ = range_message.field_of_view / 2;

  geometry_msgs::PointStamped in, out;
  in.header.stamp = range_message.header.stamp;
  in.header.frame_id = range_message.header.frame_id;

  if (!tf_->canTransform(global_frame_, in.header.frame_id, in.header.stamp, ros::Duration(transform_tolerance_)))
  {
    ROS_ERROR_THROTTLE(1.0, "Range sensor layer can't transform from %s to %s at %f",
                       global_frame_.c_str(), in.header.frame_id.c_str(),
                       in.header.stamp.toSec());
    return;
  }

  tf_->transform(in, out, global_frame_);

  double ox = out.point.x, oy = out.point.y;

  in.point.x = range_message.range;

  tf_->transform(in, out, global_frame_);

  double tx = out.point.x, ty = out.point.y;

  // calculate target props
  double dx = tx - ox, dy = ty - oy, theta = atan2(dy, dx), d = sqrt(dx * dx + dy * dy);

  // Integer Bounds of Update
  int bx0, by0, bx1, by1;

  // Triangle that will be really updated; the other cells within bounds are ignored
  // This triangle is formed by the origin and left and right sides of sonar cone
  int Ox, Oy, Ax, Ay, Bx, By;

  // Bounds includes the origin
  worldToMapNoBounds(ox, oy, Ox, Oy);
  bx1 = bx0 = Ox;
  by1 = by0 = Oy;
  touch(ox, oy, &min_x_, &min_y_, &max_x_, &max_y_);

  // Update Map with Target Point
  unsigned int aa, ab;
  if (worldToMap(tx, ty, aa, ab))
  {
    setCost(aa, ab, 233);
    touch(tx, ty, &min_x_, &min_y_, &max_x_, &max_y_);
  }

  double mx, my;

  // Update left side of sonar cone
  mx = ox + cos(theta - max_angle_) * d * 1.2;
  my = oy + sin(theta - max_angle_) * d * 1.2;
  worldToMapNoBounds(mx, my, Ax, Ay);
  bx0 = std::min(bx0, Ax);
  bx1 = std::max(bx1, Ax);
  by0 = std::min(by0, Ay);
  by1 = std::max(by1, Ay);
  touch(mx, my, &min_x_, &min_y_, &max_x_, &max_y_);

  // Update right side of sonar cone
  mx = ox + cos(theta + max_angle_) * d * 1.2;
  my = oy + sin(theta + max_angle_) * d * 1.2;

  worldToMapNoBounds(mx, my, Bx, By);
  bx0 = std::min(bx0, Bx);
  bx1 = std::max(bx1, Bx);
  by0 = std::min(by0, By);
  by1 = std::max(by1, By);
  touch(mx, my, &min_x_, &min_y_, &max_x_, &max_y_);

  // Limit Bounds to Grid
  bx0 = std::max(0, bx0);
  by0 = std::max(0, by0);
  bx1 = std::min(static_cast<int>(size_x_), bx1);
  by1 = std::min(static_cast<int>(size_y_), by1);

  for (unsigned int x = bx0; x <= (unsigned int)bx1; x++)
  {
    for (unsigned int y = by0; y <= (unsigned int)by1; y++)
    {
      bool update_xy_cell = true;

      // Unless inflate_cone_ is set to 100 %, we update cells only within the (partially inflated) sensor cone,
      // projected on the costmap as a triangle. 0 % corresponds to just the triangle, but if your sensor fov is
      // very narrow, the covered area can become zero due to cell discretization. See wiki description for more
      // details
      if (inflate_cone_ < 1.0)
      {
        // Determine barycentric coordinates
        int w0 = orient2d(Ax, Ay, Bx, By, x, y);
        int w1 = orient2d(Bx, By, Ox, Oy, x, y);
        int w2 = orient2d(Ox, Oy, Ax, Ay, x, y);

        // Barycentric coordinates inside area threshold; this is not mathematically sound at all, but it works!
        float bcciath = -inflate_cone_ * area(Ax, Ay, Bx, By, Ox, Oy);
        update_xy_cell = w0 >= bcciath && w1 >= bcciath && w2 >= bcciath;
      }

      if (update_xy_cell)
      {
        double wx, wy;
        mapToWorld(x, y, wx, wy);
        update_cell(ox, oy, theta, range_message.range, wx, wy, clear_sensor_cone);
      }
    }
  }

  buffered_readings_++;
  last_reading_time_ = ros::Time::now();
  if (use_decay_)
    removeOutdatedReadings();
}

void RangeSensorLayer::removeOutdatedReadings()
{
  std::map<std::pair<unsigned int, unsigned int>, double>::iterator it_map;

  double removal_time = last_reading_time_.toSec() - pixel_decay_;
  for (it_map = marked_point_history_.begin() ; it_map != marked_point_history_.end() ; it_map++ )
  {
    if (it_map->second < removal_time)
    {
      marked_point_history_.erase(it_map);
      setCost(std::get<0>(it_map->first), std::get<1>(it_map->first), costmap_2d::FREE_SPACE);
    }
  }
}

void RangeSensorLayer::update_cell(double ox, double oy, double ot, double r, double nx, double ny, bool clear)
{
  unsigned int x, y;
  if (worldToMap(nx, ny, x, y))
  {
    double dx = nx - ox, dy = ny - oy;
    double theta = atan2(dy, dx) - ot;
    theta = angles::normalize_angle(theta);
    double phi = sqrt(dx * dx + dy * dy);
    double sensor = 0.0;
    if (!clear)
      sensor = sensor_model(r, phi, theta);
    double prior = to_prob(getCost(x, y));
    double prob_occ = sensor * prior;
    double prob_not = (1 - sensor) * (1 - prior);
    double new_prob = prob_occ / (prob_occ + prob_not);

    ROS_DEBUG("%f %f | %f %f = %f", dx, dy, theta, phi, sensor);
    ROS_DEBUG("%f | %f %f | %f", prior, prob_occ, prob_not, new_prob);
    unsigned char c = to_cost(new_prob);

    setCost(x, y, c);
    if (use_decay_)
    {
      std::pair<unsigned int, unsigned int> coordinate_pair(x, y);
      // If the point has a score high enough to be marked in the costmap, we add it's time to the marked_point_history
      if (c > to_cost(mark_threshold_))
        marked_point_history_[coordinate_pair] = last_reading_time_.toSec();
      // If the point score is not high enough, we try to find it in the mark history point.
      // In the case we find it in the marked_point_history
      // we clear it from the map so we won't checked already cleared point
      else if (c < to_cost(clear_threshold_))
      {
        std::map<std::pair<unsigned int, unsigned int>, double>::iterator it_clear;
        it_clear = marked_point_history_.find(coordinate_pair);
        if (it_clear != marked_point_history_.end())
          marked_point_history_.erase(it_clear);
      }
    }
  }
}

void RangeSensorLayer::resetRange()
{
  min_x_ = min_y_ =  std::numeric_limits<double>::max();
  max_x_ = max_y_ = -std::numeric_limits<double>::max();
}

void RangeSensorLayer::updateBounds(double robot_x, double robot_y, double robot_yaw,
                                    double* min_x, double* min_y, double* max_x, double* max_y)
{
  if (layered_costmap_->isRolling())
    updateOrigin(robot_x - getSizeInMetersX() / 2, robot_y - getSizeInMetersY() / 2);

  updateCostmap();

  *min_x = std::min(*min_x, min_x_);
  *min_y = std::min(*min_y, min_y_);
  *max_x = std::max(*max_x, max_x_);
  *max_y = std::max(*max_y, max_y_);

  resetRange();

  if (!enabled_)
  {
    current_ = true;
    return;
  }

  if (buffered_readings_ == 0)
  {
    if (no_readings_timeout_ > 0.0 &&
        (ros::Time::now() - last_reading_time_).toSec() > no_readings_timeout_)
    {
      ROS_WARN_THROTTLE(2.0, "No range readings received for %.2f seconds, " \
                        "while expected at least every %.2f seconds.",
                        (ros::Time::now() - last_reading_time_).toSec(), no_readings_timeout_);
      current_ = false;
    }
  }
}

void RangeSensorLayer::updateCosts(costmap_2d::Costmap2D& master_grid, int min_i, int min_j, int max_i, int max_j)
{
  if (!enabled_)
    return;

  unsigned char* master_array = master_grid.getCharMap();
  unsigned int span = master_grid.getSizeInCellsX();
  unsigned char clear = to_cost(clear_threshold_), mark = to_cost(mark_threshold_);

  for (int j = min_j; j < max_j; j++)
  {
    unsigned int it = j * span + min_i;
    for (int i = min_i; i < max_i; i++)
    {
      unsigned char prob = costmap_[it];
      unsigned char current;
      if (prob == costmap_2d::NO_INFORMATION)
      {
        it++;
        continue;
      }
      else if (prob > mark)
        current = costmap_2d::LETHAL_OBSTACLE;
      else if (prob < clear)
        current = costmap_2d::FREE_SPACE;
      else
      {
        it++;
        continue;
      }

      unsigned char old_cost = master_array[it];

      if (old_cost == NO_INFORMATION || old_cost < current)
        master_array[it] = current;
      it++;
    }
  }

  buffered_readings_ = 0;
  current_ = true;
}

void RangeSensorLayer::reset()
{
  ROS_DEBUG("Reseting range sensor layer...");
  deactivate();
  resetMaps();
  current_ = true;
  activate();
}

void RangeSensorLayer::deactivate()
{
  range_msgs_buffer_.clear();
}

void RangeSensorLayer::activate()
{
  range_msgs_buffer_.clear();
}

}  // namespace range_sensor_layer