场景：Gazebo+ROS+PX4硬件(hitl模式）+QGC+Depth_camera，实现半实物仿真系统搭建

基于以上场景，实现无人机指控、导航、避障算法的仿真平台的搭建
官方硬件在环仿真关系图

一、连接PX4硬件，设置（hitl,硬件在环仿真模式）,测试硬件在环仿真模式

官方参考链接: PX4 HITL SETUP

STEP1：将PX4硬件连接到QGC，设置HIL enabled

STEP2:编译Gazebo-classic上的仿真模块

(1)Build PX4 with Gazebo Classic (in order to build the Gazebo Classic plugins).

cd <Firmware_clone>
DONT_RUN=1 make px4_sitl_default gazebo-classic

(2)设置参数，打开Tools/simulation/gazebo-classic/sitl_gazebo-classic/models/iris_hitl/iris_hitl.sdf).找到文件的 mavlink_interface plugin 分区，将 serialEnabled 和 hil_mode 参数更改为 true。
注意：串口为ttyACM0,可以使用dmesg| grep "tty"进行验证
(3)配置环境变量

source Tools/simulation/gazebo-classic/setup_gazebo.bash $(pwd) $(pwd)/build/px4_sitl_default

(4)启动Gazebo

gazebo Tools/simulation/gazebo-classic/sitl_gazebo-classic/worlds/hitl_iris.world

(5)转发mavlink到其他电脑

mavlink-routerd -e 192.168.100.6:14550 127.0.0.1:14550

最后一个为server，前面为client
以上为PX4+Gazebo半实物仿真系统，还没有添加ROS模块

二、通过ROS启动半实物仿真模型，启动depth_camera话题，启动mavros功能包

STEP1 启动gazebo_ros节点，加载世界模型

cd <PX4-Autopilot_clone>
source Tools/simulation/gazebo-classic/setup_gazebo.bash $(pwd) $(pwd)/build/px4_sitl_default
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:$(pwd)/Tools/simulation/gazebo-classic/sitl_gazebo-classic

roslaunch gazebo_ros empty_world.launch world_name:=$(pwd)/Tools/simulation/gazebo-classic/sitl_gazebo-classic/worlds/empty.world

STEP2 启动无人机模型，iris_hitl_depth_camera,为iris_hitl加装了深度相机的模型，会输出深度和rgb话题

<?xml version="1.0" ?>
<sdf version="1.5">
  <model name='iris_hitl_depth_camera'>
    <include>
      <uri>model://iris_hitl</uri>
    </include>

    <include>
      <uri>model://depth_camera</uri>
      <pose>0.1 0 0 0 0 0</pose>
    </include>
    <joint name="depth_camera_joint" type="revolute">
      <child>depth_camera::link</child>
      <parent>iris::base_link</parent>
      <axis>
        <xyz>0 0 1</xyz>
        <limit>
          <upper>0</upper>
          <lower>0</lower>
        </limit>
      </axis>
    </joint>

  </model>
</sdf>

rosrun gazebo_ros spawn_model -sdf -file $(pwd)/Tools/simulation/gazebo-classic/sitl_gazebo-classic/models/iris/iris_hitl_depth_camera.sdf -model iris -x 0 -y 0 -z 0 -R 0 -P 0 -Y 0

STEP3 开启MAVROS节点，将mavlink消息转发为ROS节点

roslaunch mavros px4.launch fcu_url:="udp://:[email protected]:14557"

以上便启动了基于ROS+gazebo+PX4的半实物仿真过程，也可以通过以下launch文件一起启动,不过原始脚本是启动的SITL软件在环仿真，可以修改其iris模型，添加hitl描述，同时不需运行sitl节点

cd <Firmware_clone>
source Tools/setup_gazebo.bash $(pwd) $(pwd)/build/px4_sitl_default
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:$(pwd)
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:$(pwd)/Tools/sitl_gazebo
roslaunch px4 mavros_posix_sitl.launch

以下就是同时启动PX4 HITL+GAZEBO+ROS+RVIZ深度图+QGC的画面，有问题可留言探讨