assisted_teleop.cpp

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

namespace assisted_teleop {
  AssistedTeleop::AssistedTeleop() : costmap_ros_("costmap", tf_), planning_thread_(NULL){
    ros::NodeHandle private_nh("~");
    private_nh.param("controller_frequency", controller_frequency_, 10.0);
    private_nh.param("num_th_samples", num_th_samples_, 20);
    private_nh.param("num_x_samples", num_x_samples_, 10);
    private_nh.param("theta_range", theta_range_, 0.7);
    private_nh.param("translational_collision_speed", collision_trans_speed_, 0.0);
    private_nh.param("rotational_collision_speed", collision_rot_speed_, 0.0);
    planner_.initialize("planner", &tf_, &costmap_ros_);

    ros::NodeHandle n;
    pub_ = n.advertise<geometry_msgs::Twist>("cmd_vel", 1);
    sub_ = n.subscribe("teleop_cmd_vel", 10, &AssistedTeleop::velCB, this);
    cmd_vel_.linear.x = 0.0;
    cmd_vel_.linear.y = 0.0;
    cmd_vel_.linear.z = 0.0;

    planning_thread_ = new boost::thread(boost::bind(&AssistedTeleop::controlLoop, this));
  }

  AssistedTeleop::~AssistedTeleop(){
    planning_thread_->join();
    delete planning_thread_;
  }

  void AssistedTeleop::velCB(const geometry_msgs::TwistConstPtr& vel){
    boost::mutex::scoped_lock lock(mutex_);
    cmd_vel_ = *vel;
  }

  void AssistedTeleop::controlLoop(){
    ros::Rate r(controller_frequency_);
    while(ros::ok()){
      Eigen::Vector3f desired_vel = Eigen::Vector3f::Zero();

      //we'll copy over odometry and velocity data for planning
      {
        boost::mutex::scoped_lock lock(mutex_);
        desired_vel[0] = cmd_vel_.linear.x;
        desired_vel[1] = cmd_vel_.linear.y;
        desired_vel[2] = cmd_vel_.angular.z;
      }

      //first, we'll check the trajectory that the user sent in... if its legal... we'll just follow it
      if(planner_.checkTrajectory(desired_vel[0], desired_vel[1], desired_vel[2], true)){
        geometry_msgs::Twist cmd;
        cmd.linear.x = desired_vel[0];
        cmd.linear.y = desired_vel[1];
        cmd.angular.z = desired_vel[2];
        pub_.publish(cmd);
        r.sleep();
        continue;
      }

      double dth = (theta_range_) / double(num_th_samples_);
      double dx = desired_vel[0] / double(num_x_samples_);
      double start_th = desired_vel[2] - theta_range_ / 2.0 ;

      Eigen::Vector3f best = Eigen::Vector3f::Zero();
      double best_dist = DBL_MAX;
      bool trajectory_found = false;

      //if we don't have a valid trajectory... we'll start checking others in the angular range specified
      for(int i = 0; i < num_x_samples_; ++i){
        Eigen::Vector3f check_vel = Eigen::Vector3f::Zero();
        check_vel[0] = desired_vel[0] - i * dx;
        check_vel[1] = desired_vel[1];
        check_vel[2] = start_th;
        for(int j = 0; j < num_th_samples_; ++j){
          check_vel[2] = start_th + j * dth;
          if(planner_.checkTrajectory(check_vel[0], check_vel[1], check_vel[2], false)){
            //if we have a legal trajectory, we'll score it based on its distance to our desired velocity
            Eigen::Vector3f diffs = (desired_vel - check_vel);
            double sq_dist = diffs[0] * diffs[0] + diffs[1] * diffs[1] + diffs[2] * diffs[2];

            //if we have a trajectory that is better than our best one so far, we'll take it
            if(sq_dist < best_dist){
              best = check_vel;
              best_dist = sq_dist;
              trajectory_found = true;
            }
          }
        }
      }

      //check if best is still zero, if it is... scale the original trajectory based on the collision_speed requested
      //but we only need to do this if the user has set a non-zero collision speed
      if(!trajectory_found && (collision_trans_speed_ > 0.0 || collision_rot_speed_ > 0.0)){
        double trans_scaling_factor = 0.0;
        double rot_scaling_factor = 0.0;
        double scaling_factor = 0.0;

        if(fabs(desired_vel[0]) > 0 && fabs(desired_vel[1]) > 0)
          trans_scaling_factor = std::min(collision_trans_speed_ / fabs(desired_vel[0]), collision_trans_speed_ / fabs(desired_vel[1]));
        else if(fabs(desired_vel[0]) > 0)
          trans_scaling_factor = collision_trans_speed_ / (fabs(desired_vel[0]));
        else if(fabs(desired_vel[1]) > 0)
          trans_scaling_factor = collision_trans_speed_ / (fabs(desired_vel[1]));

        if(fabs(desired_vel[2]) > 0)
          rot_scaling_factor = collision_rot_speed_ / (fabs(desired_vel[2]));

        if(collision_trans_speed_ > 0.0 && collision_rot_speed_ > 0.0)
          scaling_factor = std::min(trans_scaling_factor, rot_scaling_factor);
        else if(collision_trans_speed_ > 0.0)
          scaling_factor = trans_scaling_factor;
        else if(collision_rot_speed_ > 0.0)
          scaling_factor = rot_scaling_factor;

        //apply the scaling factor
        best = scaling_factor * best;
      }

      geometry_msgs::Twist best_cmd;
      best_cmd.linear.x = best[0];
      best_cmd.linear.y = best[1];
      best_cmd.angular.z = best[2];
      pub_.publish(best_cmd);

      r.sleep();
    }
  }
};


int main(int argc, char** argv){
  ros::init(argc, argv, "assisted_teleop");
  assisted_teleop::AssistedTeleop at;
  ros::spin();
  return 0;
}