scan.cpp

// Copyright (c) 2022 Samsung R&D Institute Russia
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#include "nav2_collision_monitor/scan.hpp"
 
#include <cmath>
#include <functional>
 
namespace nav2_collision_monitor
{
 
Scan::Scan(
  const nav2_util::LifecycleNode::WeakPtr & node,
  const std::string & source_name,
  const std::shared_ptr<tf2_ros::Buffer> tf_buffer,
  const std::string & base_frame_id,
  const std::string & global_frame_id,
  const tf2::Duration & transform_tolerance,
  const rclcpp::Duration & source_timeout,
  const bool base_shift_correction)
: Source(
    node, source_name, tf_buffer, base_frame_id, global_frame_id,
    transform_tolerance, source_timeout, base_shift_correction),
  data_(nullptr)
{
  RCLCPP_INFO(logger_, "[%s]: Creating Scan", source_name_.c_str());
}
 
Scan::~Scan()
{
  RCLCPP_INFO(logger_, "[%s]: Destroying Scan", source_name_.c_str());
  data_sub_.reset();
}
 
void Scan::configure()
{
  Source::configure();
  auto node = node_.lock();
  if (!node) {
    throw std::runtime_error{"Failed to lock node"};
  }
 
  std::string source_topic;
 
  // Laser scanner has no own parameters
  getCommonParameters(source_topic);
 
  rclcpp::QoS scan_qos = rclcpp::SensorDataQoS();  // set to default
  data_sub_ = node->create_subscription<sensor_msgs::msg::LaserScan>(
    source_topic, scan_qos,
    std::bind(&Scan::dataCallback, this, std::placeholders::_1));
}
 
void Scan::getData(
  const rclcpp::Time & curr_time,
  std::vector<Point> & data) const
{
  // Ignore data from the source if it is not being published yet or
  // not being published for a long time
  if (data_ == nullptr) {
    return;
  }
  if (!sourceValid(data_->header.stamp, curr_time)) {
    return;
  }
 
  tf2::Transform tf_transform;
  if (base_shift_correction_) {
    // Obtaining the transform to get data from source frame and time where it was received
    // to the base frame and current time
    if (
      !nav2_util::getTransform(
        data_->header.frame_id, data_->header.stamp,
        base_frame_id_, curr_time, global_frame_id_,
        transform_tolerance_, tf_buffer_, tf_transform))
    {
      return;
    }
  } else {
    // Obtaining the transform to get data from source frame to base frame without time shift
    // considered. Less accurate but much more faster option not dependent on state estimation
    // frames.
    if (
      !nav2_util::getTransform(
        data_->header.frame_id, base_frame_id_,
        transform_tolerance_, tf_buffer_, tf_transform))
    {
      return;
    }
  }
 
  // Calculate poses and refill data array
  float angle = data_->angle_min;
  for (size_t i = 0; i < data_->ranges.size(); i++) {
    if (data_->ranges[i] >= data_->range_min && data_->ranges[i] <= data_->range_max) {
      // Transform point coordinates from source frame -> to base frame
      tf2::Vector3 p_v3_s(
        data_->ranges[i] * std::cos(angle),
        data_->ranges[i] * std::sin(angle),
        0.0);
      tf2::Vector3 p_v3_b = tf_transform * p_v3_s;
 
      // Refill data array
      data.push_back({p_v3_b.x(), p_v3_b.y()});
    }
    angle += data_->angle_increment;
  }
}
 
void Scan::dataCallback(sensor_msgs::msg::LaserScan::ConstSharedPtr msg)
{
  data_ = msg;
}
 
}  // namespace nav2_collision_monitor