approach_and_translate_stage.cpp

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/* Author: Ioan Sucan */

#include <moveit/pick_place/pick_place.h>
#include <moveit/pick_place/approach_and_translate_stage.h>
#include <moveit/trajectory_processing/trajectory_tools.h>
#include <eigen_conversions/eigen_msg.h>
#include <ros/console.h>

namespace pick_place
{
  
ApproachAndTranslateStage::ApproachAndTranslateStage(const planning_scene::PlanningSceneConstPtr &scene,
                                                     const collision_detection::AllowedCollisionMatrixConstPtr &collision_matrix) :
  ManipulationStage("approach & translate"),
  planning_scene_(scene),
  collision_matrix_(collision_matrix)
{
  max_goal_count_ = GetGlobalPickPlaceParams().max_goal_count_;
  max_fail_ = GetGlobalPickPlaceParams().max_fail_;
  max_step_ = GetGlobalPickPlaceParams().max_step_;
  jump_factor_ = GetGlobalPickPlaceParams().jump_factor_;
}

namespace
{

bool isStateCollisionFree(const planning_scene::PlanningScene *planning_scene,
                          const collision_detection::AllowedCollisionMatrix *collision_matrix,
                          bool verbose,
                          const trajectory_msgs::JointTrajectory *grasp_posture,
                          robot_state::RobotState *state,
                          const robot_state::JointModelGroup *group,
                          const double *joint_group_variable_values)
{
  state->setJointGroupPositions(group, joint_group_variable_values);
  
  collision_detection::CollisionRequest req;
  req.verbose = verbose;
  req.group_name = group->getName();
  
  if (grasp_posture->joint_names.size() > 0)
  {
    // apply the grasp posture for the end effector (we always apply it here since it could be the case the sampler changes this posture)
    for (std::size_t i = 0 ; i < grasp_posture->points.size() ; ++i)
    {
      state->setVariablePositions(grasp_posture->joint_names, grasp_posture->points[i].positions);
      collision_detection::CollisionResult res;
      planning_scene->checkCollision(req, res, *state, *collision_matrix);
      if (res.collision)
        return false;
    }
  }
  else
  {
    collision_detection::CollisionResult res;
    planning_scene->checkCollision(req, res, *state, *collision_matrix);
    if (res.collision)
      return false;
  }
  return planning_scene->isStateFeasible(*state);
}

bool samplePossibleGoalStates(const ManipulationPlanPtr &plan, const robot_state::RobotState &reference_state,
  double min_distance, unsigned int attempts)
{
  // initialize with scene state
  robot_state::RobotStatePtr token_state(new robot_state::RobotState(reference_state));
  const robot_state::JointModelGroup *jmg = plan->shared_data_->planning_group_;
  for (unsigned int j = 0 ; j < attempts ; ++j)
  {
    double min_d = std::numeric_limits<double>::infinity();

    // Samples given the constraints, populating the joint state group
    if (plan->goal_sampler_->sample(*token_state, plan->shared_data_->max_goal_sampling_attempts_))
    {
      // Check if this new sampled state is closest we've found so far
      for (std::size_t i = 0 ; i < plan->possible_goal_states_.size() ; ++i)
      {
        double d = plan->possible_goal_states_[i]->distance(*token_state, plan->shared_data_->planning_group_);
        if (d < min_d)
          min_d = d;
      }
      if (min_d >= min_distance)
      {
        plan->possible_goal_states_.push_back(token_state);
        return true;
      }
    }
  }
  return false;
}

// This function is called during trajectory execution, after the gripper is closed, to attach the currently gripped object
bool executeAttachObject(const ManipulationPlanSharedDataConstPtr &shared_plan_data,
                         const trajectory_msgs::JointTrajectory &detach_posture,
                         const plan_execution::ExecutableMotionPlan *motion_plan)
{
  ROS_DEBUG("Applying attached object diff to maintained planning scene (attaching/detaching object to end effector)");
  bool ok = false;
  {
    planning_scene_monitor::LockedPlanningSceneRW ps(motion_plan->planning_scene_monitor_);
    moveit_msgs::AttachedCollisionObject msg = shared_plan_data->diff_attached_object_;
    // remember the configuration of the gripper before the grasp;
    // this configuration will be set again when releasing the object
    msg.detach_posture = detach_posture;
    ok = ps->processAttachedCollisionObjectMsg(msg);
  }
  motion_plan->planning_scene_monitor_->triggerSceneUpdateEvent((planning_scene_monitor::PlanningSceneMonitor::SceneUpdateType)
    (planning_scene_monitor::PlanningSceneMonitor::UPDATE_GEOMETRY + planning_scene_monitor::PlanningSceneMonitor::UPDATE_STATE));
  return ok;
}

// Add the close end effector trajectory to the overall plan (after the approach trajectory, before the retreat)
void addGripperTrajectory(const ManipulationPlanPtr &plan, const collision_detection::AllowedCollisionMatrixConstPtr &collision_matrix, const std::string &name)
{
  // Check if a "closed" end effector configuration was specified
  if (!plan->retreat_posture_.joint_names.empty())
  {
    robot_state::RobotStatePtr ee_closed_state(new robot_state::RobotState(plan->trajectories_.back().trajectory_->getLastWayPoint()));

    robot_trajectory::RobotTrajectoryPtr ee_closed_traj(new robot_trajectory::RobotTrajectory(
        ee_closed_state->getRobotModel(), plan->shared_data_->end_effector_group_->getName()));
    ee_closed_traj->setRobotTrajectoryMsg(*ee_closed_state, plan->retreat_posture_);
    // If user has defined a time for it's gripper movement time, don't add the DEFAULT_GRASP_POSTURE_COMPLETION_DURATION
    if (plan->retreat_posture_.points.size() > 0  && plan->retreat_posture_.points.back().time_from_start > ros::Duration(0.0)){
        ee_closed_traj->addPrefixWayPoint(ee_closed_state, 0.0);
    }
    else { // Do what was done before
        ee_closed_traj->addPrefixWayPoint(ee_closed_state, PickPlace::DEFAULT_GRASP_POSTURE_COMPLETION_DURATION);
    }

    plan_execution::ExecutableTrajectory et(ee_closed_traj, name);

    // Add a callback to attach the object to the EE after closing the gripper
    et.effect_on_success_ = boost::bind(&executeAttachObject, plan->shared_data_, plan->approach_posture_, _1);
    et.allowed_collision_matrix_ = collision_matrix;
    plan->trajectories_.push_back(et);

  }
  else
  {
    ROS_WARN_STREAM("No joint states of grasp postures have been defined in the pick place action.");
  }
}

} // annonymous namespace

bool ApproachAndTranslateStage::evaluate(const ManipulationPlanPtr &plan) const
{
  const robot_model::JointModelGroup *jmg = plan->shared_data_->planning_group_;
  // compute what the maximum distance reported between any two states in the planning group could be, and keep 1% of that;
  // this is the minimum distance between sampled goal states
  const double min_distance = 0.01 * jmg->getMaximumExtent();

  // convert approach direction and retreat direction to Eigen structures
  Eigen::Vector3d approach_direction, retreat_direction;
  tf::vectorMsgToEigen(plan->approach_.direction.vector, approach_direction);
  tf::vectorMsgToEigen(plan->retreat_.direction.vector, retreat_direction);

  // if translation vectors are specified in the frame of the ik link name, then we assume the frame is local; otherwise, the frame is global
  bool approach_direction_is_global_frame = !robot_state::Transforms::sameFrame(plan->approach_.direction.header.frame_id, plan->shared_data_->ik_link_->getName());
  bool retreat_direction_is_global_frame  = !robot_state::Transforms::sameFrame(plan->retreat_.direction.header.frame_id,  plan->shared_data_->ik_link_->getName());

  // transform the input vectors in accordance to frame specified in the header;
  if (approach_direction_is_global_frame)
    approach_direction = planning_scene_->getFrameTransform(plan->approach_.direction.header.frame_id).rotation() * approach_direction;
  if (retreat_direction_is_global_frame)
    retreat_direction = planning_scene_->getFrameTransform(plan->retreat_.direction.header.frame_id).rotation() * retreat_direction;

  // state validity checking during the approach must ensure that the gripper posture is that for pre-grasping
  robot_state::GroupStateValidityCallbackFn approach_validCallback = boost::bind(&isStateCollisionFree, planning_scene_.get(),
                                                                                 collision_matrix_.get(), verbose_, &plan->approach_posture_, _1, _2, _3);
  plan->goal_sampler_->setVerbose(verbose_);
  std::size_t attempted_possible_goal_states = 0;
  do // continously sample possible goal states
  {
    for (std::size_t i = attempted_possible_goal_states ; i < plan->possible_goal_states_.size() && !signal_stop_ ; ++i, ++attempted_possible_goal_states)
    {
      // if we are trying to get as close as possible to the goal (maximum one meter)
      if (plan->shared_data_->minimize_object_distance_)
      {
        static const double MAX_CLOSE_UP_DIST = 1.0;
        robot_state::RobotStatePtr close_up_state(new robot_state::RobotState(*plan->possible_goal_states_[i]));
        std::vector<robot_state::RobotStatePtr> close_up_states;
        double d_close_up = close_up_state->
          computeCartesianPath(plan->shared_data_->planning_group_,
                               close_up_states, plan->shared_data_->ik_link_,
                               approach_direction, approach_direction_is_global_frame, MAX_CLOSE_UP_DIST,
                               max_step_, jump_factor_, approach_validCallback);
        // if progress towards the object was made, update the desired goal state
        if (d_close_up > 0.0 && close_up_states.size() > 1)
          *plan->possible_goal_states_[i]  = *close_up_states[close_up_states.size() - 2];
      }

      // try to compute a straight line path that arrives at the goal using the specified approach direction
      robot_state::RobotStatePtr first_approach_state(new robot_state::RobotState(*plan->possible_goal_states_[i]));

      std::vector<robot_state::RobotStatePtr> approach_states;
      double d_approach = first_approach_state->computeCartesianPath(plan->shared_data_->planning_group_, approach_states, plan->shared_data_->ik_link_,
                                                                     -approach_direction, approach_direction_is_global_frame, plan->approach_.desired_distance,
                                                                     max_step_, jump_factor_, approach_validCallback);

      // if we were able to follow the approach direction for sufficient length, try to compute a retreat direction
      if (d_approach > plan->approach_.min_distance && !signal_stop_)
      {
        if (plan->retreat_.desired_distance > 0.0)
        {
          // construct a planning scene that is just a diff on top of our actual planning scene
          planning_scene::PlanningScenePtr planning_scene_after_approach = planning_scene_->diff();

          // assume the current state of the diff world is the one we plan to reach
          planning_scene_after_approach->getCurrentStateNonConst() = *plan->possible_goal_states_[i];

          // apply the difference message to this world that virtually attaches the object we are manipulating
          planning_scene_after_approach->processAttachedCollisionObjectMsg(plan->shared_data_->diff_attached_object_);

          // state validity checking during the retreat after the grasp must ensure the gripper posture is that of the actual grasp
          robot_state::GroupStateValidityCallbackFn retreat_validCallback = boost::bind(&isStateCollisionFree, planning_scene_after_approach.get(),
                                                                                        collision_matrix_.get(), verbose_, &plan->retreat_posture_, _1, _2, _3);

          // try to compute a straight line path that moves from the goal in a desired direction
          robot_state::RobotStatePtr last_retreat_state(new robot_state::RobotState(planning_scene_after_approach->getCurrentState()));
          std::vector<robot_state::RobotStatePtr> retreat_states;
          double d_retreat = last_retreat_state->computeCartesianPath(plan->shared_data_->planning_group_, retreat_states, plan->shared_data_->ik_link_,
                                                                       retreat_direction, retreat_direction_is_global_frame, plan->retreat_.desired_distance,
                                                                       max_step_, jump_factor_, retreat_validCallback);

          // if sufficient progress was made in the desired direction, we have a goal state that we can consider for future stages
          if (d_retreat > plan->retreat_.min_distance && !signal_stop_)
          {
            // Create approach trajectory
            std::reverse(approach_states.begin(), approach_states.end());
            robot_trajectory::RobotTrajectoryPtr approach_traj(new robot_trajectory::RobotTrajectory(planning_scene_->getRobotModel(), plan->shared_data_->planning_group_->getName()));
            for (std::size_t k = 0 ; k < approach_states.size() ; ++k)
              approach_traj->addSuffixWayPoint(approach_states[k], 0.0);

            // Create retreat trajectory
            robot_trajectory::RobotTrajectoryPtr retreat_traj(new robot_trajectory::RobotTrajectory(planning_scene_->getRobotModel(), plan->shared_data_->planning_group_->getName()));
            for (std::size_t k = 0 ; k < retreat_states.size() ; ++k)
              retreat_traj->addSuffixWayPoint(retreat_states[k], 0.0);

            // Add timestamps to approach|retreat trajectories
            time_param_.computeTimeStamps(*approach_traj);
            time_param_.computeTimeStamps(*retreat_traj);

            // Convert approach trajectory to an executable trajectory
            plan_execution::ExecutableTrajectory et_approach(approach_traj, "approach");
            et_approach.allowed_collision_matrix_ = collision_matrix_;
            plan->trajectories_.push_back(et_approach);

            // Add gripper close trajectory
            addGripperTrajectory(plan, collision_matrix_, "grasp");

            // Convert retreat trajectory to an executable trajectory
            plan_execution::ExecutableTrajectory et_retreat(retreat_traj, "retreat");
            et_retreat.allowed_collision_matrix_ = collision_matrix_;
            plan->trajectories_.push_back(et_retreat);

            plan->approach_state_ = approach_states.front();
            return true;
          }
        }
        else // No retreat was specified, so package up approach and grip trajectories.
        {
          // Reset the approach_state_ RobotStatePtr so that we can retry computing the cartesian path
          plan->approach_state_.swap(first_approach_state);

          // Create approach trajectory
          std::reverse(approach_states.begin(), approach_states.end());
          robot_trajectory::RobotTrajectoryPtr approach_traj(new robot_trajectory::RobotTrajectory(planning_scene_->getRobotModel(), plan->shared_data_->planning_group_->getName()));
          for (std::size_t k = 0 ; k < approach_states.size() ; ++k)
            approach_traj->addSuffixWayPoint(approach_states[k], 0.0);

          // Add timestamps to approach trajectories
          time_param_.computeTimeStamps(*approach_traj);

          // Convert approach trajectory to an executable trajectory
          plan_execution::ExecutableTrajectory et_approach(approach_traj, "approach");
          et_approach.allowed_collision_matrix_ = collision_matrix_;
          plan->trajectories_.push_back(et_approach);

          // Add gripper close trajectory
          addGripperTrajectory(plan, collision_matrix_, "grasp");

          plan->approach_state_ = approach_states.front();

          return true;
        }
      }

    }
  }
  while (plan->possible_goal_states_.size() < max_goal_count_ && !signal_stop_ && samplePossibleGoalStates(plan, planning_scene_->getCurrentState(), min_distance, max_fail_));

  plan->error_code_.val = moveit_msgs::MoveItErrorCodes::PLANNING_FAILED;

  return false;
}

}