给下列程序添加英文注释：bool MoveBase::getRobotPose(geometry_msgs::PoseStamped& global_pose, costmap_2d::Costmap2DROS* costmap) { tf2::toMsg(tf2::Transform::getIdentity(), global_pose.pose); geometry_msgs::PoseStamped robot_pose; tf2::toMsg(tf2::Transform::getIdentity(), robot_pose.pose); robot_pose.header.frame_id = robot_base_frame_; robot_pose.header.stamp = ros::Time(); // latest available ros::Time current_time = ros::Time::now(); // save time for checking tf delay later // get robot pose on the given costmap frame try { tf_.transform(robot_pose, global_pose, costmap->getGlobalFrameID()); } catch (tf2::LookupException& ex) { ROS_ERROR_THROTTLE(1.0, "No Transform available Error looking up robot pose: %s\n", ex.what()); return false; } catch (tf2::ConnectivityException& ex) { ROS_ERROR_THROTTLE(1.0, "Connectivity Error looking up robot pose: %s\n", ex.what()); return false; } catch (tf2::ExtrapolationException& ex) { ROS_ERROR_THROTTLE(1.0, "Extrapolation Error looking up robot pose: %s\n", ex.what()); return false; } // check if global_pose time stamp is within costmap transform tolerance if (current_time.toSec() - global_pose.header.stamp.toSec() > costmap->getTransformTolerance()) { ROS_WARN_THROTTLE(1.0, "Transform timeout for %s. " \ "Current time: %.4f, pose stamp: %.4f, tolerance: %.4f", costmap->getName().c_str(), current_time.toSec(), global_pose.header.stamp.toSec(), costmap->getTransformTolerance()); return false; } return true; }

// Function to get the robot pose in the given costmap frame
bool MoveBase::getRobotPose(geometry_msgs::PoseStamped& global_pose, costmap_2d::Costmap2DROS* costmap) {
// Set the global pose to the identity transform
tf2::toMsg(tf2::Transform::getIdentity(), global_pose.pose);
// Create a new pose for the robot and set it to the identity transform
geometry_msgs::PoseStamped robot_pose;
tf2::toMsg(tf2::Transform::getIdentity(), robot_pose.pose);
// Set the frame ID for the robot pose to the robot base frame
robot_pose.header.frame_id = robot_base_frame_;
// Set the time stamp for the robot pose to the latest available time
robot_pose.header.stamp = ros::Time(); // latest available
// Save the current time for checking the tf delay later
ros::Time current_time = ros::Time::now(); // save time for checking tf delay later

// Get the robot pose on the given costmap frame
try
{
tf_.transform(robot_pose, global_pose, costmap->getGlobalFrameID());
}
catch (tf2::LookupException& ex)
{
// If the transform lookup fails, print an error message and return false
ROS_ERROR_THROTTLE(1.0, "No Transform available Error looking up robot pose: %s\n", ex.what());
return false;
}
catch (tf2::ConnectivityException& ex)
{
// If there is a connectivity error, print an error message and return false
ROS_ERROR_THROTTLE(1.0, "Connectivity Error looking up robot pose: %s\n", ex.what());
return false;
}
catch (tf2::ExtrapolationException& ex)
{
// If there is an extrapolation error, print an error message and return false
ROS_ERROR_THROTTLE(1.0, "Extrapolation Error looking up robot pose: %s\n", ex.what());
return false;
}

// Check if the time stamp of the global pose is within the costmap transform tolerance
if (current_time.toSec() - global_pose.header.stamp.toSec() > costmap->getTransformTolerance())
{
// If the time stamp is outside the tolerance, print a warning and return false
ROS_WARN_THROTTLE(1.0, "Transform timeout for %s. " \
"Current time: %.4f, pose stamp: %.4f, tolerance: %.4f", costmap->getName().c_str(),
current_time.toSec(), global_pose.header.stamp.toSec(), costmap->getTransformTolerance());
return false;
}

// Return true if the robot pose was successfully retrieved
return true;
}