goal_functions.cpp

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* Author: Eitan Marder-Eppstein
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#include <base_local_planner/goal_functions.h>

namespace base_local_planner {
  double distance(double x1, double y1, double x2, double y2){
    return sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
  }

  bool goalPositionReached(const tf::Stamped<tf::Pose>& global_pose, double goal_x, double goal_y, double xy_goal_tolerance){
    double dist = distance(global_pose.getOrigin().x(), global_pose.getOrigin().y(), goal_x, goal_y);
    return fabs(dist) <= xy_goal_tolerance;
  }

  bool goalOrientationReached(const tf::Stamped<tf::Pose>& global_pose, double goal_th, double yaw_goal_tolerance){
    double yaw = tf::getYaw(global_pose.getRotation());
    return fabs(angles::shortest_angular_distance(yaw, goal_th)) <= yaw_goal_tolerance;
  }

  void publishPlan(const std::vector<geometry_msgs::PoseStamped>& path, const ros::Publisher& pub, double r, double g, double b, double a){
    //given an empty path we won't do anything
    if(path.empty())
      return;

    //create a path message
    nav_msgs::Path gui_path;
    gui_path.poses.resize(path.size());
    gui_path.header.frame_id = path[0].header.frame_id;
    gui_path.header.stamp = path[0].header.stamp;

    // Extract the plan in world co-ordinates, we assume the path is all in the same frame
    for(unsigned int i=0; i < path.size(); i++){
      gui_path.poses[i] = path[i];
    }

    pub.publish(gui_path);
  }

  void prunePlan(const tf::Stamped<tf::Pose>& global_pose, std::vector<geometry_msgs::PoseStamped>& plan, std::vector<geometry_msgs::PoseStamped>& global_plan){
    ROS_ASSERT(global_plan.size() >= plan.size());
    std::vector<geometry_msgs::PoseStamped>::iterator it = plan.begin();
    std::vector<geometry_msgs::PoseStamped>::iterator global_it = global_plan.begin();
    while(it != plan.end()){
      const geometry_msgs::PoseStamped& w = *it;
      // Fixed error bound of 2 meters for now. Can reduce to a portion of the map size or based on the resolution
      double x_diff = global_pose.getOrigin().x() - w.pose.position.x;
      double y_diff = global_pose.getOrigin().y() - w.pose.position.y;
      double distance_sq = x_diff * x_diff + y_diff * y_diff;
      if(distance_sq < 1){
        ROS_DEBUG("Nearest waypoint to <%f, %f> is <%f, %f>\n", global_pose.getOrigin().x(), global_pose.getOrigin().y(), w.pose.position.x, w.pose.position.y);
        break;
      }
      it = plan.erase(it);
      global_it = global_plan.erase(global_it);
    }
  }

  bool transformGlobalPlan(const tf::TransformListener& tf, const std::vector<geometry_msgs::PoseStamped>& global_plan, 
      const costmap_2d::Costmap2DROS& costmap, const std::string& global_frame, 
      std::vector<geometry_msgs::PoseStamped>& transformed_plan){
    const geometry_msgs::PoseStamped& plan_pose = global_plan[0];

    transformed_plan.clear();

    try{
      if (!global_plan.size() > 0)
      {
        ROS_ERROR("Recieved plan with zero length");
        return false;
      }

      tf::StampedTransform transform;
      tf.lookupTransform(global_frame, ros::Time(), 
          plan_pose.header.frame_id, plan_pose.header.stamp, 
          plan_pose.header.frame_id, transform);

      //let's get the pose of the robot in the frame of the plan
      tf::Stamped<tf::Pose> robot_pose;
      robot_pose.setIdentity();
      robot_pose.frame_id_ = costmap.getBaseFrameID();
      robot_pose.stamp_ = ros::Time();
      tf.transformPose(plan_pose.header.frame_id, robot_pose, robot_pose);

      //we'll keep points on the plan that are within the window that we're looking at
      double dist_threshold = std::max(costmap.getSizeInCellsX() * costmap.getResolution() / 2.0, costmap.getSizeInCellsY() * costmap.getResolution() / 2.0);

      unsigned int i = 0;
      double sq_dist_threshold = dist_threshold * dist_threshold;
      double sq_dist = DBL_MAX;

      //we need to loop to a point on the plan that is within a certain distance of the robot
      while(i < (unsigned int)global_plan.size() && sq_dist > sq_dist_threshold){
        double x_diff = robot_pose.getOrigin().x() - global_plan[i].pose.position.x;
        double y_diff = robot_pose.getOrigin().y() - global_plan[i].pose.position.y;
        sq_dist = x_diff * x_diff + y_diff * y_diff;
        ++i;
      }

      //make sure not to count the first point that is too far away
      if(i > 0)
        --i;

      tf::Stamped<tf::Pose> tf_pose;
      geometry_msgs::PoseStamped newer_pose;

      //now we'll transform until points are outside of our distance threshold
      while(i < (unsigned int)global_plan.size() && sq_dist < sq_dist_threshold){
        double x_diff = robot_pose.getOrigin().x() - global_plan[i].pose.position.x;
        double y_diff = robot_pose.getOrigin().y() - global_plan[i].pose.position.y;
        sq_dist = x_diff * x_diff + y_diff * y_diff;

        const geometry_msgs::PoseStamped& pose = global_plan[i];
        poseStampedMsgToTF(pose, tf_pose);
        tf_pose.setData(transform * tf_pose);
        tf_pose.stamp_ = transform.stamp_;
        tf_pose.frame_id_ = global_frame;
        poseStampedTFToMsg(tf_pose, newer_pose);

        transformed_plan.push_back(newer_pose);

        ++i;
      }
    }
    catch(tf::LookupException& ex) {
      ROS_ERROR("No Transform available Error: %s\n", ex.what());
      return false;
    }
    catch(tf::ConnectivityException& ex) {
      ROS_ERROR("Connectivity Error: %s\n", ex.what());
      return false;
    }
    catch(tf::ExtrapolationException& ex) {
      ROS_ERROR("Extrapolation Error: %s\n", ex.what());
      if (global_plan.size() > 0)
        ROS_ERROR("Global Frame: %s Plan Frame size %d: %s\n", global_frame.c_str(), (unsigned int)global_plan.size(), global_plan[0].header.frame_id.c_str());

      return false;
    }

    return true;
  }

  bool isGoalReached(const tf::TransformListener& tf, const std::vector<geometry_msgs::PoseStamped>& global_plan, 
      const costmap_2d::Costmap2DROS& costmap_ros, const std::string& global_frame, 
      const nav_msgs::Odometry& base_odom, double rot_stopped_vel, double trans_stopped_vel,
      double xy_goal_tolerance, double yaw_goal_tolerance){
    const geometry_msgs::PoseStamped& plan_goal_pose = global_plan.back();
    tf::Stamped<tf::Pose> goal_pose;

    try{
      if (!global_plan.size() > 0)
      {
        ROS_ERROR("Recieved plan with zero length");
        return false;
      }

      tf::StampedTransform transform;
      tf.lookupTransform(global_frame, ros::Time(), 
          plan_goal_pose.header.frame_id, plan_goal_pose.header.stamp, 
          plan_goal_pose.header.frame_id, transform);

      poseStampedMsgToTF(plan_goal_pose, goal_pose);
      goal_pose.setData(transform * goal_pose);
      goal_pose.stamp_ = transform.stamp_;
      goal_pose.frame_id_ = global_frame;

    }
    catch(tf::LookupException& ex) {
      ROS_ERROR("No Transform available Error: %s\n", ex.what());
      return false;
    }
    catch(tf::ConnectivityException& ex) {
      ROS_ERROR("Connectivity Error: %s\n", ex.what());
      return false;
    }
    catch(tf::ExtrapolationException& ex) {
      ROS_ERROR("Extrapolation Error: %s\n", ex.what());
      if (global_plan.size() > 0)
        ROS_ERROR("Global Frame: %s Plan Frame size %d: %s\n", global_frame.c_str(), (unsigned int)global_plan.size(), global_plan[0].header.frame_id.c_str());

      return false;
    }

    //we assume the global goal is the last point in the global plan
    double goal_x = goal_pose.getOrigin().getX();
    double goal_y = goal_pose.getOrigin().getY();

    double yaw = tf::getYaw(goal_pose.getRotation());

    double goal_th = yaw;

    tf::Stamped<tf::Pose> global_pose;
    if(!costmap_ros.getRobotPose(global_pose))
      return false;

    //check to see if we've reached the goal position
    if(goalPositionReached(global_pose, goal_x, goal_y, xy_goal_tolerance)){
      //check to see if the goal orientation has been reached
      if(goalOrientationReached(global_pose, goal_th, yaw_goal_tolerance)){
        //make sure that we're actually stopped before returning success
        if(stopped(base_odom, rot_stopped_vel, trans_stopped_vel))
          return true;
      }
    }

    return false;
  }

  bool stopped(const nav_msgs::Odometry& base_odom, 
      const double& rot_stopped_velocity, const double& trans_stopped_velocity){
    return fabs(base_odom.twist.twist.angular.z) <= rot_stopped_velocity 
      && fabs(base_odom.twist.twist.linear.x) <= trans_stopped_velocity
      && fabs(base_odom.twist.twist.linear.y) <= trans_stopped_velocity;
  }
};