trajectory_blender_transition_window.cpp

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#include <pilz_industrial_motion_planner/trajectory_blender_transition_window.h>
 
#include <algorithm>
#include <memory>
#include <math.h>
#include <tf2_eigen/tf2_eigen.hpp>
#include <moveit/planning_interface/planning_interface.h>
 
namespace
{
static const rclcpp::Logger LOGGER =
    rclcpp::get_logger("moveit.pilz_industrial_motion_planner.trajectory_blender_transition_window");
}
 
bool pilz_industrial_motion_planner::TrajectoryBlenderTransitionWindow::blend(
    const planning_scene::PlanningSceneConstPtr& planning_scene,
    const pilz_industrial_motion_planner::TrajectoryBlendRequest& req,
    pilz_industrial_motion_planner::TrajectoryBlendResponse& res)
{
  RCLCPP_INFO(LOGGER, "Start trajectory blending using transition window.");
 
  double sampling_time = 0.;
  if (!validateRequest(req, sampling_time, res.error_code))
  {
    RCLCPP_ERROR(LOGGER, "Trajectory blend request is not valid.");
    return false;
  }
 
  // search for intersection points of the two trajectories with the blending
  // sphere
  // intersection points belongs to blend trajectory after blending
  std::size_t first_intersection_index;
  std::size_t second_intersection_index;
  if (!searchIntersectionPoints(req, first_intersection_index, second_intersection_index))
  {
    RCLCPP_ERROR(LOGGER, "Blend radius to large.");
    res.error_code.val = moveit_msgs::msg::MoveItErrorCodes::INVALID_MOTION_PLAN;
    return false;
  }
 
  // Select blending period and adjust the start and end point of the blend
  // phase
  std::size_t blend_align_index;
  determineTrajectoryAlignment(req, first_intersection_index, second_intersection_index, blend_align_index);
 
  // blend the trajectories in Cartesian space
  pilz_industrial_motion_planner::CartesianTrajectory blend_trajectory_cartesian;
  blendTrajectoryCartesian(req, first_intersection_index, second_intersection_index, blend_align_index, sampling_time,
                           blend_trajectory_cartesian);
 
  // generate the blending trajectory in joint space
  std::map<std::string, double> initial_joint_position, initial_joint_velocity;
  for (const std::string& joint_name :
       req.first_trajectory->getFirstWayPointPtr()->getJointModelGroup(req.group_name)->getActiveJointModelNames())
  {
    initial_joint_position[joint_name] =
        req.first_trajectory->getWayPoint(first_intersection_index - 1).getVariablePosition(joint_name);
    initial_joint_velocity[joint_name] =
        req.first_trajectory->getWayPoint(first_intersection_index - 1).getVariableVelocity(joint_name);
  }
  trajectory_msgs::msg::JointTrajectory blend_joint_trajectory;
  moveit_msgs::msg::MoveItErrorCodes error_code;
 
  if (!generateJointTrajectory(planning_scene, limits_.getJointLimitContainer(), blend_trajectory_cartesian,
                               req.group_name, req.link_name, initial_joint_position, initial_joint_velocity,
                               blend_joint_trajectory, error_code, true))
  {
    // LCOV_EXCL_START
    RCLCPP_INFO(LOGGER, "Failed to generate joint trajectory for blending trajectory.");
    res.error_code.val = error_code.val;
    return false;
    // LCOV_EXCL_STOP
  }
 
  res.first_trajectory = std::make_shared<robot_trajectory::RobotTrajectory>(req.first_trajectory->getRobotModel(),
                                                                             req.first_trajectory->getGroup());
  res.blend_trajectory = std::make_shared<robot_trajectory::RobotTrajectory>(req.first_trajectory->getRobotModel(),
                                                                             req.first_trajectory->getGroup());
  res.second_trajectory = std::make_shared<robot_trajectory::RobotTrajectory>(req.first_trajectory->getRobotModel(),
                                                                              req.first_trajectory->getGroup());
 
  // set the three trajectories after blending in response
  // erase the points [first_intersection_index, back()] from the first
  // trajectory
  for (size_t i = 0; i < first_intersection_index; ++i)
  {
    res.first_trajectory->insertWayPoint(i, req.first_trajectory->getWayPoint(i),
                                         req.first_trajectory->getWayPointDurationFromPrevious(i));
  }
 
  // append the blend trajectory
  res.blend_trajectory->setRobotTrajectoryMsg(req.first_trajectory->getFirstWayPoint(), blend_joint_trajectory);
  // copy the points [second_intersection_index, len] from the second trajectory
  for (size_t i = second_intersection_index + 1; i < req.second_trajectory->getWayPointCount(); ++i)
  {
    res.second_trajectory->insertWayPoint(i - (second_intersection_index + 1), req.second_trajectory->getWayPoint(i),
                                          req.second_trajectory->getWayPointDurationFromPrevious(i));
  }
 
  // adjust the time from start
  res.second_trajectory->setWayPointDurationFromPrevious(0, sampling_time);
 
  res.error_code.val = moveit_msgs::msg::MoveItErrorCodes::SUCCESS;
  return true;
}
 
bool pilz_industrial_motion_planner::TrajectoryBlenderTransitionWindow::validateRequest(
    const pilz_industrial_motion_planner::TrajectoryBlendRequest& req, double& sampling_time,
    moveit_msgs::msg::MoveItErrorCodes& error_code) const
{
  RCLCPP_DEBUG(LOGGER, "Validate the trajectory blend request.");
 
  // check planning group
  if (!req.first_trajectory->getRobotModel()->hasJointModelGroup(req.group_name))
  {
    RCLCPP_ERROR_STREAM(LOGGER, "Unknown planning group: " << req.group_name);
    error_code.val = moveit_msgs::msg::MoveItErrorCodes::INVALID_GROUP_NAME;
    return false;
  }
 
  // check link exists
  if (!req.first_trajectory->getRobotModel()->hasLinkModel(req.link_name) &&
      !req.first_trajectory->getLastWayPoint().hasAttachedBody(req.link_name))
  {
    RCLCPP_ERROR_STREAM(LOGGER, "Unknown link name: " << req.link_name);
    error_code.val = moveit_msgs::msg::MoveItErrorCodes::INVALID_LINK_NAME;
    return false;
  }
 
  if (req.blend_radius <= 0)
  {
    RCLCPP_ERROR(LOGGER, "Blending radius must be positive");
    error_code.val = moveit_msgs::msg::MoveItErrorCodes::INVALID_MOTION_PLAN;
    return false;
  }
 
  // end position of the first trajectory and start position of second
  // trajectory must be the same
  if (!pilz_industrial_motion_planner::isRobotStateEqual(
          req.first_trajectory->getLastWayPoint(), req.second_trajectory->getFirstWayPoint(), req.group_name, EPSILON))
  {
    RCLCPP_ERROR_STREAM(
        LOGGER, "During blending the last point of the preceding and the first point of the succeeding trajectory");
    error_code.val = moveit_msgs::msg::MoveItErrorCodes::INVALID_MOTION_PLAN;
    return false;
  }
 
  // same uniform sampling time
  if (!pilz_industrial_motion_planner::determineAndCheckSamplingTime(req.first_trajectory, req.second_trajectory,
                                                                     EPSILON, sampling_time))
  {
    error_code.val = moveit_msgs::msg::MoveItErrorCodes::INVALID_MOTION_PLAN;
    return false;
  }
 
  // end position of the first trajectory and start position of second
  // trajectory must have zero
  // velocities/accelerations
  if (!pilz_industrial_motion_planner::isRobotStateStationary(req.first_trajectory->getLastWayPoint(), req.group_name,
                                                              EPSILON) ||
      !pilz_industrial_motion_planner::isRobotStateStationary(req.second_trajectory->getFirstWayPoint(), req.group_name,
                                                              EPSILON))
  {
    RCLCPP_ERROR(LOGGER, "Intersection point of the blending trajectories has non-zero velocities/accelerations.");
    error_code.val = moveit_msgs::msg::MoveItErrorCodes::INVALID_MOTION_PLAN;
    return false;
  }
 
  return true;
}
 
void pilz_industrial_motion_planner::TrajectoryBlenderTransitionWindow::blendTrajectoryCartesian(
    const pilz_industrial_motion_planner::TrajectoryBlendRequest& req, const std::size_t first_interse_index,
    const std::size_t second_interse_index, const std::size_t blend_align_index, double sampling_time,
    pilz_industrial_motion_planner::CartesianTrajectory& trajectory) const
{
  // other fields of the trajectory
  trajectory.group_name = req.group_name;
  trajectory.link_name = req.link_name;
 
  // Pose on first trajectory
  Eigen::Isometry3d blend_sample_pose1 =
      req.first_trajectory->getWayPoint(first_interse_index).getFrameTransform(req.link_name);
 
  // Pose on second trajectory
  Eigen::Isometry3d blend_sample_pose2 =
      req.second_trajectory->getWayPoint(second_interse_index).getFrameTransform(req.link_name);
 
  // blend the trajectory
  double blend_sample_num = second_interse_index + blend_align_index - first_interse_index + 1;
  pilz_industrial_motion_planner::CartesianTrajectoryPoint waypoint;
  blend_sample_pose2 = req.second_trajectory->getFirstWayPoint().getFrameTransform(req.link_name);
 
  // Pose on blending trajectory
  Eigen::Isometry3d blend_sample_pose;
  for (std::size_t i = 0; i < blend_sample_num; ++i)
  {
    // if the first trajectory does not reach the last sample, update
    if ((first_interse_index + i) < req.first_trajectory->getWayPointCount())
    {
      blend_sample_pose1 = req.first_trajectory->getWayPoint(first_interse_index + i).getFrameTransform(req.link_name);
    }
 
    // if after the alignment, the second trajectory starts, update
    if ((first_interse_index + i) > blend_align_index)
    {
      blend_sample_pose2 = req.second_trajectory->getWayPoint(first_interse_index + i - blend_align_index)
                               .getFrameTransform(req.link_name);
    }
 
    double s = (i + 1) / blend_sample_num;
    double alpha = 6 * std::pow(s, 5) - 15 * std::pow(s, 4) + 10 * std::pow(s, 3);
 
    // blend the translation
    blend_sample_pose.translation() = blend_sample_pose1.translation() +
                                      alpha * (blend_sample_pose2.translation() - blend_sample_pose1.translation());
 
    // blend the orientation
    Eigen::Quaterniond start_quat(blend_sample_pose1.rotation());
    Eigen::Quaterniond end_quat(blend_sample_pose2.rotation());
    blend_sample_pose.linear() = start_quat.slerp(alpha, end_quat).toRotationMatrix();
 
    // push to the trajectory
    waypoint.pose = tf2::toMsg(blend_sample_pose);
    waypoint.time_from_start = rclcpp::Duration::from_seconds((i + 1.0) * sampling_time);
    trajectory.points.push_back(waypoint);
  }
}
 
bool pilz_industrial_motion_planner::TrajectoryBlenderTransitionWindow::searchIntersectionPoints(
    const pilz_industrial_motion_planner::TrajectoryBlendRequest& req, std::size_t& first_interse_index,
    std::size_t& second_interse_index) const
{
  RCLCPP_INFO(LOGGER, "Search for start and end point of blending trajectory.");
 
  // compute the position of the center of the blend sphere
  // (last point of the first trajectory, first point of the second trajectory)
  Eigen::Isometry3d circ_pose = req.first_trajectory->getLastWayPoint().getFrameTransform(req.link_name);
 
  // Searh for intersection points according to distance
  if (!linearSearchIntersectionPoint(req.link_name, circ_pose.translation(), req.blend_radius, req.first_trajectory,
                                     true, first_interse_index))
  {
    RCLCPP_ERROR_STREAM(LOGGER, "Intersection point of first trajectory not found.");
    return false;
  }
  RCLCPP_INFO_STREAM(LOGGER, "Intersection point of first trajectory found, index: " << first_interse_index);
 
  if (!linearSearchIntersectionPoint(req.link_name, circ_pose.translation(), req.blend_radius, req.second_trajectory,
                                     false, second_interse_index))
  {
    RCLCPP_ERROR_STREAM(LOGGER, "Intersection point of second trajectory not found.");
    return false;
  }
 
  RCLCPP_INFO_STREAM(LOGGER, "Intersection point of second trajectory found, index: " << second_interse_index);
  return true;
}
 
void pilz_industrial_motion_planner::TrajectoryBlenderTransitionWindow::determineTrajectoryAlignment(
    const pilz_industrial_motion_planner::TrajectoryBlendRequest& req, std::size_t first_interse_index,
    std::size_t second_interse_index, std::size_t& blend_align_index) const
{
  size_t way_point_count_1 = req.first_trajectory->getWayPointCount() - first_interse_index;
  size_t way_point_count_2 = second_interse_index + 1;
 
  if (way_point_count_1 > way_point_count_2)
  {
    blend_align_index = req.first_trajectory->getWayPointCount() - second_interse_index - 1;
  }
  else
  {
    blend_align_index = first_interse_index;
  }
}