文章目录
一、仿真环境
使用现有开源的仿真环境---从零开始搭建一台ROS开源迷你无人车，作者已经配置好小车模型以及gazebo环境，imu频率已改为200HZ，文中也有详细的说明，这里就不再介绍。
启动仿真
bash
roslaunch steer_mini_gazebo steer_mini_sim_sensors_VLP16_lio_sam.launch 
话题如下：
bash
/ackermann_steering_controller/cmd_vel
/ackermann_steering_controller/odom
/clock
/gains/left_rear_joint/parameter_descriptions
/gains/left_rear_joint/parameter_updates
/gains/right_rear_joint/parameter_descriptions
/gains/right_rear_joint/parameter_updates
/gazebo/link_states
/gazebo/model_states
/gazebo/parameter_descriptions
/gazebo/parameter_updates
/gazebo/set_link_state
/gazebo/set_model_state
/imu/data
/joint_states
/rosout
/rosout_agg
/tf
/tf_static
/velodyne_points控制小车移动，打开一个终端，录制所有话题（也可录制需要的话题），会自动在终端所在的文件夹下根据当前时间产生bag文件。
bash
rosbag record -a二、lio_sam建图
lio_sam的安装测试可参考Lego-LOAM和LIO_SAM的使用及地图的处理
1.修改配置文件
在LIO-SAM/config下的params.yaml文件中
修改为自己小车的话题
bash
# Topics
pointCloudTopic: "/velodyne_points"
imuTopic: "/imu/data"
odomTopic: "/odometry/imu"
gpsTopic: "odometry/gpsz" 修改保存路径
bash
# Export settings
savePCD: true
savePCDDirectory: "/Downloads/" 修改imu到雷达的坐标变换
bash
# Extrinsics: T_lb (lidar -> imu)
extrinsicTrans: [0.0, 0.0, 0.0]
extrinsicRot: [1, 0, 0,
0, 1, 0,
0, 0, 1]
extrinsicRPY: [1, 0, 0,
0, 1, 0,
0, 0, 1]其它的保持默认即可。
2.开始建图
bash
roslaunch lio_sam run.launch
rosbag play your.bag 
保存的PCD---GlobalMap.pcd
三、ndt_matching定位
1.新建启动文件
使用Autoware.ai中的ndt_matching定位模块。为了适配前方，需要对应仿真的数据进行如下修改
autoware.ai/src/autoware/documentation/autoware_quickstart_examples/config路径：
新建headless_setup_steer_mini.yaml 内容如下：
bash
tf_x: 0
tf_y: 0
tf_z: 0.115
tf_yaw: 0
tf_pitch: 0
tf_roll: 0
localizer: velodyne
use_sim_time: false.autoware/data/tf 路径：
新建tf_steer_mini.launch
bash
<launch>
<!-- worldからmapへのtf -->
<node pkg="tf2_ros" type="static_transform_publisher" name="world_to_map" args="0 0 0 0 0 0 /world /map" />
<!-- mapからmobilityへのtf -->
<!-- <node pkg="tf2_ros" type="static_transform_publisher" name="map_to_mobility" args="0 0 0 0 0 0 /map /mobility" />-->
<node pkg="tf2_ros" type="static_transform_publisher" name="base_link_to_velodyne" args="0 0 0.115 0 0 0 /base_link /velodyne" />
</launch>autoware.ai/src/autoware/documentation/autoware_quickstart_examples/launch/rosbag_demo路径下：
新建my_map_steer_mini.launch内容如下
bash
<launch>
<rosparam command="load" file="$(find autoware_quickstart_examples)/config/headless_setup_steer_mini.yaml" />
<include file="$(env HOME)/.autoware/data/tf/tf_steer_mini.launch"/>
<node pkg="map_file" type="points_map_loader" name="points_map_loader" args="noupdate $(env HOME)/.autoware/data/map/pointcloud_map/GlobalMap.pcd"/>
</launch>autoware.ai/src/autoware/core_perception/lidar_localizer/launch路径下：
新建ndt_matching_steer_mini.launch内容如下：
bash
<launch>
<arg name="method_type" default="0" /> <!-- pcl_generic=0, pcl_anh=1, pcl_anh_gpu=2, pcl_openmp=3 -->
<arg name="use_gnss" default="0" />
<arg name="use_odom" default="true" />
<arg name="use_imu" default="true" />
<arg name="imu_upside_down" default="false" />
<arg name="imu_topic" default="/imu/data" />
<arg name="queue_size" default="1" />
<arg name="offset" default="linear" />
<arg name="get_height" default="false" />
<arg name="use_local_transform" default="false" />
<arg name="sync" default="false" />
<arg name="output_log_data" default="false" />
<arg name="gnss_reinit_fitness" default="500.0" />
<node pkg="lidar_localizer" type="ndt_matching" name="ndt_matching" output="log">
<param name="method_type" value="$(arg method_type)" />
<param name="use_gnss" value="$(arg use_gnss)" />
<param name="use_odom" value="$(arg use_odom)" />
<param name="use_imu" value="$(arg use_imu)" />
<param name="imu_upside_down" value="$(arg imu_upside_down)" />
<param name="imu_topic" value="$(arg imu_topic)" />
<param name="queue_size" value="$(arg queue_size)" />
<param name="offset" value="$(arg offset)" />
<param name="get_height" value="$(arg get_height)" />
<param name="use_local_transform" value="$(arg use_local_transform)" />
<param name="output_log_data" value="$(arg output_log_data)" />
<param name="gnss_reinit_fitness" value="$(arg gnss_reinit_fitness)" />
<remap from="/points_raw" to="/sync_drivers/points_raw" if="$(arg sync)" />
</node>
</launch>同时修改ndt_matching.cpp中的里程计接收话题
cpp
// ros::Subscriber odom_sub = nh.subscribe("/vehicle/odom", _queue_size * 10, odom_callback); //default
ros::Subscriber odom_sub = nh.subscribe("/ackermann_steering_controller/odom", _queue_size * 10, odom_callback);autoware.ai/src/autoware/core_perception/points_downsampler/launch路径下：
新建points_downsample_steer_mini.launch
bash
<launch>
<arg name="sync" default="false" />
<arg name="node_name" default="voxel_grid_filter" />
<arg name="points_topic" default="/velodyne_points" />
<arg name="output_log" default="false" />
<arg name="measurement_range" default="200" />
<node pkg="points_downsampler" name="$(arg node_name)" type="$(arg node_name)">
<param name="points_topic" value="$(arg points_topic)" />
<remap from="/points_raw" to="/sync_drivers/points_raw" if="$(arg sync)" />
<param name="output_log" value="$(arg output_log)" />
<param name="measurement_range" value="$(arg measurement_range)" />
</node>
</launch>autoware.ai/src/autoware/documentation/autoware_quickstart_examples/launch/rosbag_demo路径下：
新建my_localization_steer_mini.launch
bash
<launch>
<!-- setting path parameter -->
<arg name="get_height" value="true" />
<!-- Setup
<include file="$(find runtime_manager)/launch_files/setup_tf.launch">
<arg name="x" value="1.2" />
<arg name="y" value="0.0" />
<arg name="z" value="2.0" />
<arg name="yaw" value="0.0" />
<arg name="pitch" value="0.0" />
<arg name="roll" value="0.0" />
<arg name="frame_id" value="/base_link" />
<arg name="child_frame_id" value="/velodyne" />
<arg name="period_in_ms" value="10"/>
</include>-->
<!-- <include file="$(find vehicle_description)/launch/vehicle_model.launch" /> -->
<!-- points downsampler -->
<include file="$(find points_downsampler)/launch/points_downsample_steer_mini.launch" />
<!-- nmea2tfpose -->
<!-- <include file="$(find gnss_localizer)/launch/nmea2tfpose.launch"/> -->
<!-- ndt_matching -->
<include file="$(find lidar_localizer)/launch/ndt_matching_steer_mini.launch">
<arg name="get_height" value="$(arg get_height)" />
</include>
</launch>2.启动
bash
roslaunch autoware_quickstart_examples my_map_steer_mini.launch
roslaunch autoware_quickstart_examples my_localization_steer_mini.launch
rviz
给定初始位姿(必须)
rosbag play your.bag效果图：
总结
以上实现了仿真场景下使用lio_sam建图以及ndt_matching定位的过程，仅仅作为测试使用，存在仿真场景较小，没有在机器人模型中添加gps数据的问题，整体上达到定位的要求。