global_reference.cpp

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//=================================================================================================
// Copyright (c) 2012, Johannes Meyer, TU Darmstadt
// All rights reserved.

// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of the Flight Systems and Automatic Control group,
//       TU Darmstadt, nor the names of its contributors may be used to
//       endorse or promote products derived from this software without
//       specific prior written permission.

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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//=================================================================================================

#include <hector_pose_estimation/global_reference.h>
#include <hector_pose_estimation/state.h>
#include <cmath>

#include <ros/console.h>

using namespace std;

namespace hector_pose_estimation {

GlobalReference::GlobalReference()
{
  parameters().add("reference_latitude",  reference_latitude_  = std::numeric_limits<double>::quiet_NaN());
  parameters().add("reference_longitude", reference_longitude_ = std::numeric_limits<double>::quiet_NaN());
  parameters().add("reference_altitude",  reference_altitude_  = std::numeric_limits<double>::quiet_NaN());
  parameters().add("reference_heading",   heading_.value       = std::numeric_limits<double>::quiet_NaN());

  reset();
}

const GlobalReferencePtr &GlobalReference::Instance()
{
  static GlobalReferencePtr instance;
  if (!instance) { instance.reset(new GlobalReference); }
  return instance;
}

void GlobalReference::reset()
{
  position_ = Position();
  heading_ = Heading();
  radius_ = Radius();

  // parameters are in degrees
  position_.latitude  = reference_latitude_ * M_PI/180.0;
  position_.longitude = reference_longitude_ * M_PI/180.0;
  position_.altitude  = reference_altitude_;
  heading_.value      = reference_heading_;

  updated();
}

ParameterList& GlobalReference::parameters() {
  return parameters_;
}

void GlobalReference::updated(bool intermediate) {
  // calculate earth radii
  if (hasPosition()) {
    radius_ = Radius(position_.latitude);
  }

  // calculate sin and cos of the heading reference
  if (hasHeading()) {
    sincos(heading_.value, &heading_.sin, &heading_.cos);
  }

  // execute update callbacks
  if (!intermediate) {
    for(std::list<UpdateCallback>::iterator cb = update_callbacks_.begin(); cb != update_callbacks_.end(); ++cb)
      (*cb)();
  }
}

GlobalReference::Heading::Heading(double heading) : value(heading)
{
  sincos(heading, &sin, &cos);
}

Quaternion GlobalReference::Heading::quaternion() const
{
  double sin_2, cos_2;
  sincos(0.5 * value, &sin_2, &cos_2);
  return Quaternion(cos_2, 0.0, 0.0, -sin_2);
}

GlobalReference::Radius::Radius(double latitude) {
  // WGS84 constants
  static const double equatorial_radius = 6378137.0;
  static const double flattening = 1.0/298.257223563;
  static const double excentrity2 = 2*flattening - flattening*flattening;

  double temp = 1.0 / (1.0 - excentrity2 * sin(latitude) * sin(latitude));
  double prime_vertical_radius = equatorial_radius * sqrt(temp);
  north = prime_vertical_radius * (1 - excentrity2) * temp;
  east  = prime_vertical_radius * cos(latitude);
}

void GlobalReference::fromWGS84(double latitude, double longitude, double &x, double &y) {
  if (!hasPosition()) {
    x = 0.0;
    y = 0.0;
    return;
  }
  double north = radius_.north * (latitude  - position_.latitude);
  double east  = radius_.east  * (longitude - position_.longitude);
  fromNorthEast(north, east, x, y);
}

void GlobalReference::toWGS84(double x, double y, double &latitude, double &longitude) {
  if (!hasPosition()) {
    latitude  = 0.0;
    longitude = 0.0;
    return;
  }

  double north, east;
  toNorthEast(x, y, north, east);
  latitude  = position_.latitude  + north / radius_.north;
  longitude = position_.longitude + east  / radius_.east;
}

void GlobalReference::fromNorthEast(double north, double east, double &x, double &y) {
  if (!hasHeading()) {
    x = 0.0;
    y = 0.0;
    return;
  }
  x = north * heading_.cos + east * heading_.sin;
  y = north * heading_.sin - east * heading_.cos;
}

void GlobalReference::toNorthEast(double x, double y, double &north, double &east) {
  if (!hasHeading()) {
    north = 0.0;
    east = 0.0;
    return;
  }
  north = x * heading_.cos + y * heading_.sin;
  east  = x * heading_.sin - y * heading_.cos;
}

GlobalReference& GlobalReference::setPosition(double latitude, double longitude, bool intermediate /* = false */) {
  position_.latitude = latitude;
  position_.longitude = longitude;
  if (!intermediate) ROS_INFO("Set new reference position to %f deg N / %f deg E", this->position().latitude * 180.0/M_PI, this->position().longitude * 180.0/M_PI);
  updated(intermediate);
  return *this;
}

GlobalReference& GlobalReference::setHeading(double heading, bool intermediate /* = false */) {
  heading_.value = heading;
  if (!intermediate) ROS_INFO("Set new reference heading to %.1f degress", this->heading() * 180.0 / M_PI);
  updated(intermediate);
  return *this;
}

GlobalReference& GlobalReference::setAltitude(double altitude, bool intermediate /* = false */) {
  position_.altitude = altitude;
  if (!intermediate) ROS_INFO("Set new reference altitude to %.2f m", this->position().altitude);
  updated(intermediate);
  return *this;
}

GlobalReference& GlobalReference::setCurrentPosition(const State& state, double new_latitude, double new_longitude) {
  State::ConstPositionType position = state.getPosition();

  // set reference to new latitude/longitude first (intermediate reference)
  setPosition(new_latitude, new_longitude, true);

  // convert current position back to WGS84 using the new reference position
  // and reset the reference position so that current position in x/y coordinates remains the same
  // This will work unless the radii at the origin and the x/y position of the robot differ too much
  toWGS84(-position.x(), -position.y(), new_latitude, new_longitude);
  setPosition(new_latitude, new_longitude);

  return *this;
}

GlobalReference& GlobalReference::setCurrentHeading(const State& state, double new_heading) {
  // get current yaw angle
  double current_yaw = state.getYaw();
  State::ConstPositionType position = state.getPosition();

  // get current position in WGS84
  double current_latitude, current_longitude;
  if (hasPosition()) {
    toWGS84(position.x(), position.y(), current_latitude, current_longitude);
  }

  // set the new reference heading
  setHeading(new_heading - (-current_yaw));

  // set the new reference position so that current position in WGS84 coordinates remains the same as before
  if (hasPosition()) {
    setCurrentPosition(state, current_latitude, current_longitude);
  }

  return *this;
}

GlobalReference& GlobalReference::setCurrentAltitude(const State& state, double new_altitude) {
  State::ConstPositionType position = state.getPosition();
  setAltitude(new_altitude - position.z());
  return *this;
}

void GlobalReference::getGeoPose(geographic_msgs::GeoPose& geopose) const
{
  Quaternion orientation(heading().quaternion());
  geopose.orientation.w = orientation.w();
  geopose.orientation.x = orientation.x();
  geopose.orientation.y = orientation.y();
  geopose.orientation.z = orientation.z();
  geopose.position.latitude  = position().latitude  * 180.0/M_PI;
  geopose.position.longitude = position().longitude * 180.0/M_PI;
  geopose.position.altitude  = position().altitude;
}

bool GlobalReference::getWorldToNavTransform(geometry_msgs::TransformStamped& transform, const std::string &world_frame, const std::string &nav_frame, const ros::Time& stamp) const
{
  // Return transform from world_frame (defined by parameters reference_latitude_, reference_longitude_, reference_altitude_ and reference_heading_)
  // to the nav_frame (this reference)
  if (isnan(reference_latitude_) ||
      isnan(reference_longitude_) ||
      isnan(reference_altitude_) ||
      isnan(reference_heading_)) {
    return false;
  }

  transform.header.stamp = stamp;
  transform.header.frame_id = world_frame;
  transform.child_frame_id = nav_frame;

  Radius reference_radius(reference_latitude_ * M_PI/180.0);
  double north = reference_radius.north * (position_.latitude  - reference_latitude_ * M_PI/180.0);
  double east  = reference_radius.east  * (position_.longitude - reference_longitude_ * M_PI/180.0);
  Heading reference_heading(reference_heading_ * M_PI/180.0);
  transform.transform.translation.x = north * reference_heading.cos + east * reference_heading.sin;
  transform.transform.translation.y = north * reference_heading.sin - east * reference_heading.cos;
  transform.transform.translation.z = position_.altitude - reference_altitude_;
  double heading_diff = heading().value - reference_heading;
  transform.transform.rotation.w =  cos(heading_diff / 2.);
  transform.transform.rotation.x =  0.0;
  transform.transform.rotation.y =  0.0;
  transform.transform.rotation.z = -sin(heading_diff / 2.);

  return true;
}

void GlobalReference::addUpdateCallback(const UpdateCallback &cb)
{
  update_callbacks_.push_back(cb);
}

} // namespace hector_pose_estimation