cartographer 纯定位---pure_localization

0. 简介

最近群里有些老哥在问cartographer纯定位相关问题，网上已有的方法均已失效，这里作者研究了下cartographer相关的流程以及源码，给出了一种简单的解决策略。

1. 旧版cartographer_ros

launch文件的修改

在启动cartographer_occupancy_grid_node节点时，增加pure_localization参数。

<node name="cartographer_occupancy_grid_node" pkg="cartographer_ros"
      type="cartographer_occupancy_grid_node" args="-resolution 0.05
                                                    -pure_localization 1" />

源文件的修改

在​​cartographer_ros/cartographer_ros/cartographer_ros/occupancy_grid_node_main.cc​​文件中

• 增加纯定位参数

DEFINE_int32(pure_localization, 0, "Pure localization !");

• 更改初始化函数，增加参数赋值

//Node::Node(const double resolution, const double publish_period_sec)
Node::Node(const int pure_localization,const double resolution, const double publish_period_sec) 
    : resolution_(resolution),
      pure_localization_(pure_localization),//kaikai.gao

• 禁止地图话题发布：

void Node::DrawAndPublish(const ::ros::WallTimerEvent& unused_timer_event) {
  if (submap_slices_.empty() || last_frame_id_.empty()) {
    return;
  }

  // 非常重要，逻辑不能出错，否则影响导航地图！
  if(pure_localization_ == 1) return;

  ::cartographer::common::MutexLocker locker(&mutex_);
  auto painted_slices = PaintSubmapSlices(submap_slices_, resolution_);
  std::unique_ptr<nav_msgs::OccupancyGrid> msg_ptr = CreateOccupancyGridMsg(
      painted_slices, resolution_, last_frame_id_, last_timestamp_);

  occupancy_grid_publisher_.publish(*msg_ptr);
}