carrot_planner.cpp

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* Authors: Eitan Marder-Eppstein, Sachin Chitta
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#include <carrot_planner/carrot_planner.h>
#include <pluginlib/class_list_macros.h>

//register this planner as a BaseGlobalPlanner plugin
PLUGINLIB_EXPORT_CLASS(carrot_planner::CarrotPlanner, nav_core::BaseGlobalPlanner)

namespace carrot_planner {

  CarrotPlanner::CarrotPlanner()
  : costmap_ros_(NULL), initialized_(false){}

  CarrotPlanner::CarrotPlanner(std::string name, costmap_2d::Costmap2DROS* costmap_ros)
  : costmap_ros_(NULL), initialized_(false){
    initialize(name, costmap_ros);
  }
  
  void CarrotPlanner::initialize(std::string name, costmap_2d::Costmap2DROS* costmap_ros){
    if(!initialized_){
      costmap_ros_ = costmap_ros;
      costmap_ = costmap_ros_->getCostmap();

      ros::NodeHandle private_nh("~/" + name);
      private_nh.param("step_size", step_size_, costmap_->getResolution());
      private_nh.param("min_dist_from_robot", min_dist_from_robot_, 0.10);
      world_model_ = new base_local_planner::CostmapModel(*costmap_); 

      initialized_ = true;
    }
    else
      ROS_WARN("This planner has already been initialized... doing nothing");
  }

  //we need to take the footprint of the robot into account when we calculate cost to obstacles
  double CarrotPlanner::footprintCost(double x_i, double y_i, double theta_i){
    if(!initialized_){
      ROS_ERROR("The planner has not been initialized, please call initialize() to use the planner");
      return -1.0;
    }

    std::vector<geometry_msgs::Point> footprint = costmap_ros_->getRobotFootprint();
    //if we have no footprint... do nothing
    if(footprint.size() < 3)
      return -1.0;

    //check if the footprint is legal
    double footprint_cost = world_model_->footprintCost(x_i, y_i, theta_i, footprint);
    return footprint_cost;
  }


  bool CarrotPlanner::makePlan(const geometry_msgs::PoseStamped& start, 
      const geometry_msgs::PoseStamped& goal, std::vector<geometry_msgs::PoseStamped>& plan){

    if(!initialized_){
      ROS_ERROR("The planner has not been initialized, please call initialize() to use the planner");
      return false;
    }

    ROS_DEBUG("Got a start: %.2f, %.2f, and a goal: %.2f, %.2f", start.pose.position.x, start.pose.position.y, goal.pose.position.x, goal.pose.position.y);

    plan.clear();
    costmap_ = costmap_ros_->getCostmap();

    if(goal.header.frame_id != costmap_ros_->getGlobalFrameID()){
      ROS_ERROR("This planner as configured will only accept goals in the %s frame, but a goal was sent in the %s frame.", 
          costmap_ros_->getGlobalFrameID().c_str(), goal.header.frame_id.c_str());
      return false;
    }

    tf::Stamped<tf::Pose> goal_tf;
    tf::Stamped<tf::Pose> start_tf;

    poseStampedMsgToTF(goal,goal_tf);
    poseStampedMsgToTF(start,start_tf);

    double useless_pitch, useless_roll, goal_yaw, start_yaw;
    start_tf.getBasis().getEulerYPR(start_yaw, useless_pitch, useless_roll);
    goal_tf.getBasis().getEulerYPR(goal_yaw, useless_pitch, useless_roll);

    //we want to step back along the vector created by the robot's position and the goal pose until we find a legal cell
    double goal_x = goal.pose.position.x;
    double goal_y = goal.pose.position.y;
    double start_x = start.pose.position.x;
    double start_y = start.pose.position.y;

    double diff_x = goal_x - start_x;
    double diff_y = goal_y - start_y;
    double diff_yaw = angles::normalize_angle(goal_yaw-start_yaw);

    double target_x = goal_x;
    double target_y = goal_y;
    double target_yaw = goal_yaw;

    bool done = false;
    double scale = 1.0;
    double dScale = 0.01;

    while(!done)
    {
      if(scale < 0)
      {
        target_x = start_x;
        target_y = start_y;
        target_yaw = start_yaw;
        ROS_WARN("The carrot planner could not find a valid plan for this goal");
        break;
      }
      target_x = start_x + scale * diff_x;
      target_y = start_y + scale * diff_y;
      target_yaw = angles::normalize_angle(start_yaw + scale * diff_yaw);
      
      double footprint_cost = footprintCost(target_x, target_y, target_yaw);
      if(footprint_cost >= 0)
      {
          done = true;
      }
      scale -=dScale;
    }

    plan.push_back(start);
    geometry_msgs::PoseStamped new_goal = goal;
    tf::Quaternion goal_quat = tf::createQuaternionFromYaw(target_yaw);

    new_goal.pose.position.x = target_x;
    new_goal.pose.position.y = target_y;

    new_goal.pose.orientation.x = goal_quat.x();
    new_goal.pose.orientation.y = goal_quat.y();
    new_goal.pose.orientation.z = goal_quat.z();
    new_goal.pose.orientation.w = goal_quat.w();

    plan.push_back(new_goal);
    return (done);
  }

};