servo.cpp

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/*      Title     : servo.cpp
 *      Project   : moveit_servo
 *      Created   : 05/17/2023
 *      Author    : Brian O'Neil, Andy Zelenak, Blake Anderson, V Mohammed Ibrahim
 */
 
#include <moveit_servo/servo.hpp>
#include <moveit_servo/utils/command.hpp>
#include <moveit_servo/utils/common.hpp>
#include <rclcpp/rclcpp.hpp>
#include <moveit/utils/logger.hpp>
 
// Disable -Wold-style-cast because all _THROTTLE macros trigger this
#pragma GCC diagnostic ignored "-Wold-style-cast"
 
namespace
{
constexpr double ROBOT_STATE_WAIT_TIME = 5.0;  // seconds
constexpr double STOPPED_VELOCITY_EPS = 1e-4;
}  // namespace
 
namespace moveit_servo
{
 
Servo::Servo(const rclcpp::Node::SharedPtr& node, std::shared_ptr<const servo::ParamListener> servo_param_listener,
             const planning_scene_monitor::PlanningSceneMonitorPtr& planning_scene_monitor)
  : node_(node)
  , logger_(moveit::getLogger("moveit.ros.servo"))
  , servo_param_listener_{ std::move(servo_param_listener) }
  , planning_scene_monitor_{ planning_scene_monitor }
{
  servo_params_ = servo_param_listener_->get_params();
 
  if (!validateParams(servo_params_))
  {
    RCLCPP_ERROR_STREAM(logger_, "Got invalid parameters, exiting.");
    std::exit(EXIT_FAILURE);
  }
 
  if (!planning_scene_monitor_->getStateMonitor()->waitForCompleteState(servo_params_.move_group_name,
                                                                        ROBOT_STATE_WAIT_TIME))
  {
    RCLCPP_ERROR(logger_, "Timeout waiting for current state");
    std::exit(EXIT_FAILURE);
  }
 
  moveit::core::RobotStatePtr robot_state = planning_scene_monitor_->getStateMonitor()->getCurrentState();
 
  // Create the collision checker and start collision checking.
  collision_monitor_ =
      std::make_unique<CollisionMonitor>(planning_scene_monitor_, servo_params_, std::ref(collision_velocity_scale_));
  collision_monitor_->start();
 
  servo_status_ = StatusCode::NO_WARNING;
 
  const auto& move_group_joint_names = planning_scene_monitor_->getRobotModel()
                                           ->getJointModelGroup(servo_params_.move_group_name)
                                           ->getActiveJointModelNames();
  // Create subgroup map
  for (const auto& sub_group_name : planning_scene_monitor_->getRobotModel()->getJointModelGroupNames())
  {
    // Skip move group
    if (sub_group_name == servo_params_.move_group_name)
    {
      continue;
    }
    const auto& subgroup_joint_names =
        planning_scene_monitor_->getRobotModel()->getJointModelGroup(sub_group_name)->getActiveJointModelNames();
 
    JointNameToMoveGroupIndexMap new_map;
    // For each joint name of the subgroup calculate the index in the move group joint vector
    for (const auto& joint_name : subgroup_joint_names)
    {
      // Find subgroup joint name in move group joint names
      const auto move_group_iterator =
          std::find(move_group_joint_names.cbegin(), move_group_joint_names.cend(), joint_name);
      // Calculate position and add a new mapping of joint name to move group joint vector position
      new_map.insert(std::make_pair<std::string, std::size_t>(
          std::string(joint_name), std::distance(move_group_joint_names.cbegin(), move_group_iterator)));
    }
    // Add new joint name to index map to existing maps
    joint_name_to_index_maps_.insert(
        std::make_pair<std::string, JointNameToMoveGroupIndexMap>(std::string(sub_group_name), std::move(new_map)));
  }
 
  // Load the smoothing plugin
  if (servo_params_.use_smoothing)
  {
    setSmoothingPlugin();
  }
  else
  {
    RCLCPP_WARN(logger_, "No smoothing plugin loaded");
  }
 
  RCLCPP_INFO_STREAM(logger_, "Servo initialized successfully");
}
 
Servo::~Servo()
{
  setCollisionChecking(false);
}
 
void Servo::setSmoothingPlugin()
{
  // Load the smoothing plugin
  try
  {
    pluginlib::ClassLoader<online_signal_smoothing::SmoothingBaseClass> smoothing_loader(
        "moveit_core", "online_signal_smoothing::SmoothingBaseClass");
    smoother_ = smoothing_loader.createUniqueInstance(servo_params_.smoothing_filter_plugin_name);
  }
  catch (pluginlib::PluginlibException& ex)
  {
    RCLCPP_ERROR(logger_, "Exception while loading the smoothing plugin '%s': '%s'",
                 servo_params_.smoothing_filter_plugin_name.c_str(), ex.what());
    std::exit(EXIT_FAILURE);
  }
 
  // Initialize the smoothing plugin
  moveit::core::RobotStatePtr robot_state = planning_scene_monitor_->getStateMonitor()->getCurrentState();
  const int num_joints =
      robot_state->getJointModelGroup(servo_params_.move_group_name)->getActiveJointModelNames().size();
  if (!smoother_->initialize(node_, planning_scene_monitor_->getRobotModel(), num_joints))
  {
    RCLCPP_ERROR(logger_, "Smoothing plugin could not be initialized");
    std::exit(EXIT_FAILURE);
  }
}
 
void Servo::doSmoothing(KinematicState& state)
{
  if (smoother_)
  {
    smoother_->doSmoothing(state.positions, state.velocities, state.accelerations);
  }
}
 
void Servo::resetSmoothing(const KinematicState& state)
{
  if (smoother_)
  {
    smoother_->reset(state.positions, state.velocities, state.accelerations);
  }
}
 
void Servo::setCollisionChecking(const bool check_collision)
{
  check_collision ? collision_monitor_->start() : collision_monitor_->stop();
}
 
bool Servo::validateParams(const servo::Params& servo_params)
{
  bool params_valid = true;
  auto robot_state = planning_scene_monitor_->getStateMonitor()->getCurrentState();
  auto joint_model_group = robot_state->getJointModelGroup(servo_params.move_group_name);
  const std::string check_yaml_string = " Check the parameters YAML file used to launch this node.";
  if (joint_model_group == nullptr)
  {
    RCLCPP_ERROR_STREAM(logger_, "The parameter 'move_group_name': `" << servo_params.move_group_name << '`'
                                                                      << " is not valid." << check_yaml_string);
    params_valid = false;
  }
 
  if (servo_params.hard_stop_singularity_threshold <= servo_params.lower_singularity_threshold)
  {
    RCLCPP_ERROR_STREAM(logger_, "The parameter 'hard_stop_singularity_threshold' "
                                 "should be greater than the parameter 'lower_singularity_threshold'. But the "
                                 "'hard_stop_singularity_threshold' is: '"
                                     << servo_params.hard_stop_singularity_threshold
                                     << "' and the 'lower_singularity_threshold' is: '"
                                     << servo_params.lower_singularity_threshold << "'" << check_yaml_string);
    params_valid = false;
  }
 
  if (!servo_params.publish_joint_positions && !servo_params.publish_joint_velocities &&
      !servo_params.publish_joint_accelerations)
  {
    RCLCPP_ERROR_STREAM(logger_, "At least one of the parameters: 'publish_joint_positions' / "
                                 "'publish_joint_velocities' / "
                                 "'publish_joint_accelerations' must be true. But they are all false."
                                     << check_yaml_string);
    params_valid = false;
  }
 
  if ((servo_params.command_out_type == "std_msgs/Float64MultiArray") && servo_params.publish_joint_positions &&
      servo_params.publish_joint_velocities)
  {
    RCLCPP_ERROR_STREAM(
        logger_, "When publishing a std_msgs/Float64MultiArray, "
                 "either the parameter 'publish_joint_positions' OR the parameter 'publish_joint_velocities' must "
                 "be set to true. But both are set to true."
                     << check_yaml_string);
    params_valid = false;
  }
 
  if (servo_params.scene_collision_proximity_threshold < servo_params.self_collision_proximity_threshold)
  {
    RCLCPP_ERROR_STREAM(logger_, "The parameter 'self_collision_proximity_threshold' should probably be less "
                                 "than or equal to the parameter 'scene_collision_proximity_threshold'. But "
                                 "'self_collision_proximity_threshold' is: '"
                                     << servo_params.self_collision_proximity_threshold
                                     << "' and 'scene_collision_proximity_threshold' is: '"
                                     << servo_params.scene_collision_proximity_threshold << "'" << check_yaml_string);
    params_valid = false;
  }
 
  if (!servo_params.active_subgroup.empty() && servo_params.active_subgroup != servo_params.move_group_name &&
      !joint_model_group->isSubgroup(servo_params.active_subgroup))
  {
    RCLCPP_ERROR_STREAM(logger_, "The parameter 'active_subgroup': '"
                                     << servo_params.active_subgroup
                                     << "' does not name a valid subgroup of 'joint group': '"
                                     << servo_params.move_group_name << "'" << check_yaml_string);
    params_valid = false;
  }
 
  const auto num_dofs = robot_state->getJointModelGroup(servo_params.move_group_name)->getActiveVariableCount();
  if (servo_params.joint_limit_margins.size() == 1u)
  {
    joint_limit_margins_.clear();
    for (size_t idx = 0; idx < num_dofs; ++idx)
    {
      joint_limit_margins_.push_back(servo_params.joint_limit_margins[0]);
    }
  }
  else if (servo_params.joint_limit_margins.size() == num_dofs)
  {
    joint_limit_margins_ = servo_params.joint_limit_margins;
  }
  else
  {
    RCLCPP_ERROR_STREAM(
        logger_, "The parameter 'joint_limit_margins' must have either a single element or the same number of "
                 "elements as the degrees of freedom in the active joint group. The size of 'joint_limit_margins' is '"
                     << servo_params.joint_limit_margins.size() << "' but the number of degrees of freedom in group '"
                     << servo_params.move_group_name << "' is '" << num_dofs << "'." << check_yaml_string);
    params_valid = false;
  }
 
  if (servo_params.max_expected_latency / MIN_POINTS_FOR_TRAJ_MSG < servo_params.publish_period)
  {
    RCLCPP_ERROR(
        logger_,
        "The publish period (%f sec) parameter must be less than 1/%d of the max expected latency parameter (%f sec).",
        servo_params.publish_period, MIN_POINTS_FOR_TRAJ_MSG, servo_params.max_expected_latency);
    params_valid = false;
  }
 
  return params_valid;
}
 
bool Servo::updateParams()
{
  bool params_updated = false;
  if (servo_param_listener_->is_old(servo_params_))
  {
    const auto params = servo_param_listener_->get_params();
 
    if (validateParams(params))
    {
      if (params.override_velocity_scaling_factor != servo_params_.override_velocity_scaling_factor)
      {
        RCLCPP_INFO_STREAM(logger_, "override_velocity_scaling_factor changed to : "
                                        << std::to_string(params.override_velocity_scaling_factor));
      }
 
      servo_params_ = params;
      params_updated = true;
    }
    else
    {
      RCLCPP_WARN_STREAM(logger_, "Parameters will not be updated.");
    }
  }
  return params_updated;
}
 
servo::Params& Servo::getParams()
{
  return servo_params_;
}
 
StatusCode Servo::getStatus() const
{
  return servo_status_;
}
 
std::string Servo::getStatusMessage() const
{
  return SERVO_STATUS_CODE_MAP.at(servo_status_);
}
 
CommandType Servo::getCommandType() const
{
  return expected_command_type_;
}
 
void Servo::setCommandType(const CommandType& command_type)
{
  expected_command_type_ = command_type;
}
 
KinematicState Servo::haltJoints(const std::vector<size_t>& joint_variables_to_halt,
                                 const KinematicState& current_state, const KinematicState& target_state) const
{
  KinematicState bounded_state(target_state.joint_names.size());
  bounded_state.joint_names = target_state.joint_names;
 
  std::stringstream halting_joint_names;
  for (const auto idx : joint_variables_to_halt)
  {
    halting_joint_names << bounded_state.joint_names[idx] + " ";
  }
  RCLCPP_WARN_STREAM(logger_, "Joint position limit reached on joints: " << halting_joint_names.str());
 
  const bool all_joint_halt =
      (getCommandType() == CommandType::JOINT_JOG && servo_params_.halt_all_joints_in_joint_mode) ||
      (getCommandType() == CommandType::TWIST && servo_params_.halt_all_joints_in_cartesian_mode);
 
  if (all_joint_halt)
  {
    // The velocities are initialized to zero by default, so we don't need to set it here.
    bounded_state.positions = current_state.positions;
  }
  else
  {
    // Halt only the joints that are out of bounds
    bounded_state.positions = target_state.positions;
    bounded_state.velocities = target_state.velocities;
    for (const auto idx : joint_variables_to_halt)
    {
      bounded_state.positions[idx] = current_state.positions[idx];
      bounded_state.velocities[idx] = 0.0;
    }
  }
 
  return bounded_state;
}
 
Eigen::VectorXd Servo::jointDeltaFromCommand(const ServoInput& command, const moveit::core::RobotStatePtr& robot_state)
{
  // Determine joint_name_group_index_map, if no subgroup is active, the map is empty
  const auto& active_subgroup_name =
      servo_params_.active_subgroup.empty() ? servo_params_.move_group_name : servo_params_.active_subgroup;
  const auto& joint_name_group_index_map = (active_subgroup_name != servo_params_.move_group_name) ?
                                               joint_name_to_index_maps_.at(servo_params_.active_subgroup) :
                                               JointNameToMoveGroupIndexMap();
 
  const int num_joints =
      robot_state->getJointModelGroup(servo_params_.move_group_name)->getActiveJointModelNames().size();
  Eigen::VectorXd joint_position_deltas(num_joints);
  joint_position_deltas.setZero();
 
  JointDeltaResult delta_result;
 
  const CommandType expected_type = getCommandType();
  if (command.index() == static_cast<size_t>(expected_type))
  {
    if (expected_type == CommandType::JOINT_JOG)
    {
      delta_result = jointDeltaFromJointJog(std::get<JointJogCommand>(command), robot_state, servo_params_,
                                            joint_name_group_index_map);
      servo_status_ = delta_result.first;
    }
    else if (expected_type == CommandType::TWIST)
    {
      // Transform the twist command to the planning frame, which is the base frame of the active subgroup's IK solver,
      // before applying it. Additionally verify there is an IK solver, and that the transformation is successful.
      const auto planning_frame_maybe = getIKSolverBaseFrame(robot_state, active_subgroup_name);
      if (planning_frame_maybe.has_value())
      {
        const auto& planning_frame = *planning_frame_maybe;
        const auto command_in_planning_frame_maybe = toPlanningFrame(std::get<TwistCommand>(command), planning_frame);
        if (command_in_planning_frame_maybe.has_value())
        {
          delta_result = jointDeltaFromTwist(*command_in_planning_frame_maybe, robot_state, servo_params_,
                                             planning_frame, joint_name_group_index_map);
          servo_status_ = delta_result.first;
        }
        else
        {
          servo_status_ = StatusCode::INVALID;
          RCLCPP_ERROR_STREAM(logger_, "Could not transform twist command to planning frame.");
        }
      }
      else
      {
        servo_status_ = StatusCode::INVALID;
        RCLCPP_ERROR(logger_, "No IK solver for planning group %s.", active_subgroup_name.c_str());
      }
    }
    else if (expected_type == CommandType::POSE)
    {
      // Transform the pose command to the planning frame, which is the base frame of the active subgroup's IK solver,
      // before applying it. The end effector frame is also extracted as the tip frame of the IK solver.
      // Additionally verify there is an IK solver, and that the transformation is successful.
      const auto planning_frame_maybe = getIKSolverBaseFrame(robot_state, active_subgroup_name);
      const auto ee_frame_maybe = getIKSolverTipFrame(robot_state, active_subgroup_name);
      if (planning_frame_maybe.has_value() && ee_frame_maybe.has_value())
      {
        const auto& planning_frame = *planning_frame_maybe;
        const auto command_in_planning_frame_maybe = toPlanningFrame(std::get<PoseCommand>(command), planning_frame);
        if (command_in_planning_frame_maybe.has_value())
        {
          delta_result = jointDeltaFromPose(*command_in_planning_frame_maybe, robot_state, servo_params_,
                                            planning_frame, *ee_frame_maybe, joint_name_group_index_map);
          servo_status_ = delta_result.first;
        }
        else
        {
          servo_status_ = StatusCode::INVALID;
          RCLCPP_ERROR_STREAM(logger_, "Could not transform pose command to planning frame.");
        }
      }
      else
      {
        servo_status_ = StatusCode::INVALID;
        RCLCPP_ERROR(logger_, "No IK solver for planning group %s.", active_subgroup_name.c_str());
      }
    }
 
    if (servo_status_ != StatusCode::INVALID)
    {
      joint_position_deltas = delta_result.second;
    }
  }
  else
  {
    servo_status_ = StatusCode::INVALID;
    RCLCPP_WARN_STREAM(logger_, "Incoming servo command type does not match known command types.");
  }
 
  return joint_position_deltas;
}
 
KinematicState Servo::getNextJointState(const moveit::core::RobotStatePtr& robot_state, const ServoInput& command)
{
  // Set status to clear
  servo_status_ = StatusCode::NO_WARNING;
 
  // Update the parameters
  updateParams();
 
  // Get the joint model group info.
  const moveit::core::JointModelGroup* joint_model_group =
      robot_state->getJointModelGroup(servo_params_.move_group_name);
 
  // Get necessary information about joints
  const std::vector<std::string> joint_names = joint_model_group->getActiveJointModelNames();
  const moveit::core::JointBoundsVector joint_bounds = joint_model_group->getActiveJointModelsBounds();
  const int num_joints = joint_names.size();
 
  // Extract current state from robot state
  KinematicState current_state = extractRobotState(robot_state, servo_params_.move_group_name);
  KinematicState target_state(num_joints);
  target_state.joint_names = joint_names;
 
  // Compute the change in joint position due to the incoming command
  Eigen::VectorXd joint_position_delta = jointDeltaFromCommand(command, robot_state);
 
  if (collision_velocity_scale_ > 0 && collision_velocity_scale_ < 1)
  {
    servo_status_ = StatusCode::DECELERATE_FOR_COLLISION;
  }
  else if (collision_velocity_scale_ == 0)
  {
    servo_status_ = StatusCode::HALT_FOR_COLLISION;
  }
 
  // Continue rest of the computations only if the command is valid
  // The computations can be skipped also in case we are halting.
  if (servo_status_ != StatusCode::INVALID && servo_status_ != StatusCode::HALT_FOR_COLLISION)
  {
    // Compute the next joint positions based on the joint position deltas
    target_state.positions = current_state.positions + joint_position_delta;
 
    // Compute the joint velocities required to reach positions
    target_state.velocities = joint_position_delta / servo_params_.publish_period;
 
    // Scale down the velocity based on joint velocity limit or user defined scaling if applicable.
    const double joint_velocity_limit_scale = jointLimitVelocityScalingFactor(
        target_state.velocities, joint_bounds, servo_params_.override_velocity_scaling_factor);
    if (joint_velocity_limit_scale < 1.0)  // 1.0 means no scaling.
    {
      RCLCPP_DEBUG_STREAM(logger_, "Joint velocity limit scaling applied by a factor of " << joint_velocity_limit_scale);
    }
    target_state.velocities *= joint_velocity_limit_scale;
 
    // Adjust joint position based on scaled down velocity
    target_state.positions = current_state.positions + (target_state.velocities * servo_params_.publish_period);
 
    // Apply collision scaling to the joint position delta
    target_state.positions =
        current_state.positions + collision_velocity_scale_ * (target_state.positions - current_state.positions);
 
    // Compute velocities based on smoothed joint positions
    target_state.velocities = (target_state.positions - current_state.positions) / servo_params_.publish_period;
 
    // Check if any joints are going past joint position limits.
    const std::vector<size_t> joint_variables_to_halt =
        jointVariablesToHalt(target_state.positions, target_state.velocities, joint_bounds, joint_limit_margins_);
 
    // Apply halting if any joints need to be halted.
    if (!joint_variables_to_halt.empty())
    {
      servo_status_ = StatusCode::JOINT_BOUND;
      target_state = haltJoints(joint_variables_to_halt, current_state, target_state);
    }
  }
 
  // Apply smoothing to the positions if a smoother was provided.
  doSmoothing(target_state);
 
  return target_state;
}
 
std::optional<Eigen::Isometry3d> Servo::getPlanningToCommandFrameTransform(const std::string& command_frame,
                                                                           const std::string& planning_frame) const
{
  const moveit::core::RobotStatePtr robot_state = planning_scene_monitor_->getStateMonitor()->getCurrentState();
  if (robot_state->knowsFrameTransform(command_frame) && (robot_state->knowsFrameTransform(planning_frame)))
  {
    return robot_state->getGlobalLinkTransform(planning_frame).inverse() *
           robot_state->getGlobalLinkTransform(command_frame);
  }
  else
  {
    try
    {
      return tf2::transformToEigen(
          planning_scene_monitor_->getTFClient()->lookupTransform(planning_frame, command_frame, rclcpp::Time(0)));
    }
    catch (tf2::TransformException& ex)
    {
      RCLCPP_ERROR(logger_, "Failed to get planning to command frame transform: %s", ex.what());
      return std::nullopt;
    }
  }
}
 
std::optional<TwistCommand> Servo::toPlanningFrame(const TwistCommand& command, const std::string& planning_frame) const
{
  Eigen::VectorXd transformed_twist = command.velocities;
 
  if (command.frame_id != planning_frame)
  {
    // Look up the transform between the planning and command frames.
    const auto planning_to_command_tf_maybe = getPlanningToCommandFrameTransform(command.frame_id, planning_frame);
    if (!planning_to_command_tf_maybe.has_value())
    {
      return std::nullopt;
    }
    const auto& planning_to_command_tf = *planning_to_command_tf_maybe;
 
    if (servo_params_.apply_twist_commands_about_ee_frame)
    {
      // If the twist command is applied about the end effector frame, simply apply the rotation of the transform.
      const auto planning_to_command_rotation = planning_to_command_tf.linear();
      const Eigen::Vector3d translation_vector =
          planning_to_command_rotation *
          Eigen::Vector3d(command.velocities[0], command.velocities[1], command.velocities[2]);
      const Eigen::Vector3d angular_vector =
          planning_to_command_rotation *
          Eigen::Vector3d(command.velocities[3], command.velocities[4], command.velocities[5]);
 
      // Update the values of the original command message to reflect the change in frame
      transformed_twist.head<3>() = translation_vector;
      transformed_twist.tail<3>() = angular_vector;
    }
    else
    {
      // If the twist command is applied about the planning frame, the spatial twist is calculated
      // as shown in Equation 3.83 in http://hades.mech.northwestern.edu/images/7/7f/MR.pdf.
      // The above equation defines twist as [angular; linear], but in our convention it is
      // [linear; angular] so the adjoint matrix is also reordered accordingly.
      Eigen::MatrixXd adjoint(6, 6);
 
      const Eigen::Matrix3d& rotation = planning_to_command_tf.rotation();
      const Eigen::Vector3d& translation = planning_to_command_tf.translation();
 
      Eigen::Matrix3d skew_translation;
      skew_translation.row(0) << 0, -translation(2), translation(1);
      skew_translation.row(1) << translation(2), 0, -translation(0);
      skew_translation.row(2) << -translation(1), translation(0), 0;
 
      adjoint.topLeftCorner(3, 3) = skew_translation * rotation;
      adjoint.topRightCorner(3, 3) = rotation;
      adjoint.bottomLeftCorner(3, 3) = rotation;
      adjoint.bottomRightCorner(3, 3).setZero();
 
      transformed_twist = adjoint * transformed_twist;
    }
  }
 
  return TwistCommand{ planning_frame, transformed_twist };
}
 
std::optional<PoseCommand> Servo::toPlanningFrame(const PoseCommand& command, const std::string& planning_frame) const
{
  const auto planning_to_command_tf_maybe = getPlanningToCommandFrameTransform(command.frame_id, planning_frame);
  if (!planning_to_command_tf_maybe)
  {
    return std::nullopt;
  }
 
  const auto& planning_to_command_tf = *planning_to_command_tf_maybe;
  return PoseCommand{ planning_frame, planning_to_command_tf * command.pose };
}
 
KinematicState Servo::getCurrentRobotState(bool block_for_current_state) const
{
  if (block_for_current_state)
  {
    bool have_current_state = false;
    while (rclcpp::ok() && !have_current_state)
    {
      have_current_state = planning_scene_monitor_->getStateMonitor()->waitForCurrentState(
          rclcpp::Clock(RCL_ROS_TIME).now(), ROBOT_STATE_WAIT_TIME /* s */);
      if (!have_current_state)
      {
        RCLCPP_WARN(logger_, "Waiting for the current state");
      }
    }
  }
  moveit::core::RobotStatePtr robot_state = planning_scene_monitor_->getStateMonitor()->getCurrentState();
  return extractRobotState(robot_state, servo_params_.move_group_name);
}
 
std::pair<bool, KinematicState> Servo::smoothHalt(const KinematicState& halt_state)
{
  auto target_state = halt_state;
 
  // If all velocities are near zero, robot has decelerated to a stop.
  bool stopped = (target_state.velocities.cwiseAbs().array() < STOPPED_VELOCITY_EPS).all();
 
  if (!stopped)
  {
    // set target velocity
    target_state.velocities *= 0.0;
 
    // scale velocity in case of obstacle
    target_state.velocities *= collision_velocity_scale_;
 
    for (long i = 0; i < halt_state.positions.size(); ++i)
    {
      target_state.positions[i] = halt_state.positions[i] + target_state.velocities[i] * servo_params_.publish_period;
      const double vel = target_state.velocities[i];
      target_state.velocities[i] = (std::abs(vel) > STOPPED_VELOCITY_EPS) ? vel : 0.0;
      target_state.accelerations[i] =
          (target_state.velocities[i] - halt_state.velocities[i]) / servo_params_.publish_period;
    }
  }
 
  // apply smoothing: this will change target position/velocity to make slow down gradual
  doSmoothing(target_state);
 
  return std::make_pair(stopped, target_state);
}
 
}  // namespace moveit_servo