rotate_recovery.cpp

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* Author: Eitan Marder-Eppstein
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#include <rotate_recovery/rotate_recovery.h>
#include <pluginlib/class_list_macros.h>

//register this planner as a RecoveryBehavior plugin
PLUGINLIB_DECLARE_CLASS(rotate_recovery, RotateRecovery, rotate_recovery::RotateRecovery, nav_core::RecoveryBehavior)

namespace rotate_recovery {
RotateRecovery::RotateRecovery(): global_costmap_(NULL), local_costmap_(NULL), 
  tf_(NULL), initialized_(false), world_model_(NULL) {} 

void RotateRecovery::initialize(std::string name, tf::TransformListener* tf,
    costmap_2d::Costmap2DROS* global_costmap, costmap_2d::Costmap2DROS* local_costmap){
  if(!initialized_){
    name_ = name;
    tf_ = tf;
    global_costmap_ = global_costmap;
    local_costmap_ = local_costmap;

    //get some parameters from the parameter server
    ros::NodeHandle private_nh("~/" + name_);
    ros::NodeHandle blp_nh("~/TrajectoryPlannerROS");

    //we'll simulate every degree by default
    private_nh.param("sim_granularity", sim_granularity_, 0.017);
    private_nh.param("frequency", frequency_, 20.0);

    blp_nh.param("acc_lim_th", acc_lim_th_, 3.2);
    blp_nh.param("max_rotational_vel", max_rotational_vel_, 1.0);
    blp_nh.param("min_in_place_rotational_vel", min_rotational_vel_, 0.4);
    blp_nh.param("yaw_goal_tolerance", tolerance_, 0.10);

    world_model_ = new base_local_planner::CostmapModel(*local_costmap_->getCostmap());

    initialized_ = true;
  }
  else{
    ROS_ERROR("You should not call initialize twice on this object, doing nothing");
  }
}

RotateRecovery::~RotateRecovery(){
  delete world_model_;
}

void RotateRecovery::runBehavior(){
  if(!initialized_){
    ROS_ERROR("This object must be initialized before runBehavior is called");
    return;
  }

  if(global_costmap_ == NULL || local_costmap_ == NULL){
    ROS_ERROR("The costmaps passed to the RotateRecovery object cannot be NULL. Doing nothing.");
    return;
  }
  ROS_WARN("Rotate recovery behavior started.");

  ros::Rate r(frequency_);
  ros::NodeHandle n;
  ros::Publisher vel_pub = n.advertise<geometry_msgs::Twist>("cmd_vel", 10);

  tf::Stamped<tf::Pose> global_pose;
  local_costmap_->getRobotPose(global_pose);

  double current_angle = -1.0 * M_PI;

  bool got_180 = false;

  double start_offset = 0 - angles::normalize_angle(tf::getYaw(global_pose.getRotation()));
  while(n.ok()){
    local_costmap_->getRobotPose(global_pose);

    double norm_angle = angles::normalize_angle(tf::getYaw(global_pose.getRotation()));
    current_angle = angles::normalize_angle(norm_angle + start_offset);

    //compute the distance left to rotate
    double dist_left = M_PI - current_angle;

    double x = global_pose.getOrigin().x(), y = global_pose.getOrigin().y();

    //check if that velocity is legal by forward simulating
    double sim_angle = 0.0;
    while(sim_angle < dist_left){
      double theta = tf::getYaw(global_pose.getRotation()) + sim_angle;

      //make sure that the point is legal, if it isn't... we'll abort
      double footprint_cost = world_model_->footprintCost(x, y, theta, local_costmap_->getRobotFootprint(), 0.0, 0.0);
      if(footprint_cost < 0.0){
        ROS_ERROR("Rotate recovery can't rotate in place because there is a potential collision. Cost: %.2f", footprint_cost);
        return;
      }

      sim_angle += sim_granularity_;
    }

    //compute the velocity that will let us stop by the time we reach the goal
    double vel = sqrt(2 * acc_lim_th_ * dist_left);

    //make sure that this velocity falls within the specified limits
    vel = std::min(std::max(vel, min_rotational_vel_), max_rotational_vel_);

    geometry_msgs::Twist cmd_vel;
    cmd_vel.linear.x = 0.0;
    cmd_vel.linear.y = 0.0;
    cmd_vel.angular.z = vel;

    vel_pub.publish(cmd_vel);

    //makes sure that we won't decide we're done right after we start
    if(current_angle < 0.0)
      got_180 = true;

    //if we're done with our in-place rotation... then return
    if(got_180 && current_angle >= (0.0 - tolerance_))
      return;

    r.sleep();
  }
}
};