get_group_urdf_capability.cpp

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/* Author: Sebastian Jahr */
 
#include "get_group_urdf_capability.h"
 
#include <moveit/moveit_cpp/moveit_cpp.h>
#include <moveit/move_group/capability_names.h>
#include <moveit/utils/logger.hpp>
#include <urdf_parser/urdf_parser.h>
 
namespace move_group
{
 
namespace
{
rclcpp::Logger getLogger()
{
  return moveit::getLogger("moveit.ros.move_group.get_urdf_service");
}
const auto JOINT_ELEMENT_CLOSING = std::string("</joint>");
const auto LINK_ELEMENT_CLOSING = std::string("</link>");
const auto ROBOT_ELEMENT_CLOSING = std::string("</robot>");
const auto GENERAL_ELEMENT_CLOSING = std::string("/>");
}  // namespace
 
GetUrdfService::GetUrdfService() : MoveGroupCapability("get_group_urdf")
{
}
 
void GetUrdfService::initialize()
{
  get_urdf_service_ = context_->moveit_cpp_->getNode()->create_service<moveit_msgs::srv::GetGroupUrdf>(
      GET_URDF_SERVICE_NAME,
      [this](const std::shared_ptr<moveit_msgs::srv::GetGroupUrdf::Request>& req,
             const std::shared_ptr<moveit_msgs::srv::GetGroupUrdf::Response>& res) {
        res->error_code.source = std::string("GetUrdfService");
        const auto subgroup = context_->moveit_cpp_->getRobotModel()->getJointModelGroup(req->group_name);
        // Check if group exists in loaded robot model
        if (!subgroup)
        {
          const auto error_string = std::string("Cannot create URDF because planning group '") + req->group_name +
                                    std::string("' does not exist");
          RCLCPP_ERROR(getLogger(), "%s", error_string.c_str());
          res->error_code.message = error_string;
          res->error_code.val = moveit_msgs::msg::MoveItErrorCodes::FAILURE;
          return;
        }
 
        std::string full_urdf_string =
            context_->moveit_cpp_->getPlanningSceneMonitor()->getRobotModelLoader()->getRDFLoader()->getURDFString();
 
        // Check if robot description string is empty
        if (full_urdf_string.empty())
        {
          const auto error_string = std::string("Couldn't get the robot description string from MoveItCpp");
          RCLCPP_ERROR(getLogger(), "%s", error_string.c_str());
          res->error_code.message = error_string;
          res->error_code.val = moveit_msgs::msg::MoveItErrorCodes::FAILURE;
          return;
        }
 
        // Create subgroup urdf
        // Create header
        res->urdf_string = std::string("<?xml version=\"1.0\" ?><robot name=\"") + req->group_name +
                           std::string("\" xmlns:xacro=\"http://ros.org/wiki/xacro\">");
 
        // Create links
        auto link_names = subgroup->getLinkModelNames();
        // Remove duplicates
        std::sort(link_names.begin(), link_names.end());
        link_names.erase(std::unique(link_names.begin(), link_names.end()), link_names.end());
 
        for (const auto& link_name : link_names)
        {
          const auto start = full_urdf_string.find("<link name=\"" + link_name + "\"");
          auto substring = full_urdf_string.substr(start, full_urdf_string.size() - start);
 
          // Link elements can be closed either by "/>" or "</link>" so we need to consider both cases
          auto const substring_without_opening = substring.substr(1, substring.size() - 2);
          auto const general_opening_pos_a = substring_without_opening.find('<');
          auto const link_closing_pos_b = substring.find(GENERAL_ELEMENT_CLOSING);
          // Case "/>"
          if (link_closing_pos_b < general_opening_pos_a)
          {
            res->urdf_string += substring.substr(0, link_closing_pos_b + GENERAL_ELEMENT_CLOSING.size());
          }
          // Case </link>
          else
          {
            res->urdf_string += substring.substr(0, substring.find(LINK_ELEMENT_CLOSING) + LINK_ELEMENT_CLOSING.size());
          }
        }
 
        // Create joints
        auto joint_names = subgroup->getJointModelNames();
        // Remove duplicates
        std::sort(joint_names.begin(), joint_names.end());
        joint_names.erase(std::unique(joint_names.begin(), joint_names.end()), joint_names.end());
        for (const auto& joint_name : joint_names)
        {
          const auto start = full_urdf_string.find("<joint name=\"" + joint_name + "\" type");
          auto substring = full_urdf_string.substr(start, full_urdf_string.size() - start);
          res->urdf_string += substring.substr(0, substring.find(JOINT_ELEMENT_CLOSING) + JOINT_ELEMENT_CLOSING.size());
 
          // If parent link model is not part of the joint group, add it
          const auto parent_link_element = subgroup->getJointModel(joint_name)->getParentLinkModel()->getName();
          if (std::find(link_names.begin(), link_names.end(), parent_link_element) == link_names.end())
          {
            auto const base_link_element = "<link name=\"" + parent_link_element + "\"/>";
            res->urdf_string += base_link_element;
            link_names.push_back(parent_link_element);
          }
        }
 
        // Add closing
        res->urdf_string += ROBOT_ELEMENT_CLOSING;
 
        //  Validate urdf file
        if (!urdf::parseURDF(res->urdf_string))
        {
          const std::string error_string = std::string("Failed to create valid urdf");
          RCLCPP_ERROR(getLogger(), "%s", error_string.c_str());
          res->error_code.message = error_string;
          res->error_code.val = moveit_msgs::msg::MoveItErrorCodes::FAILURE;
          return;
        }
        res->error_code.val = moveit_msgs::msg::MoveItErrorCodes::SUCCESS;
      }  // End of callback function
  );
}
}  // namespace move_group
 
#include <pluginlib/class_list_macros.hpp>
 
PLUGINLIB_EXPORT_CLASS(move_group::GetUrdfService, move_group::MoveGroupCapability)