1. 前提：安装好 ros 和 gazebo

  2. 安装 PX4：

    git clone https://github.com/PX4/PX4-Autopilot.git

  3. offboard 环境部署：

    # 建立工作空间
mkdir -p catkin_ws/src
cd catkin_ws
catkin init
wstool init src
   
# 安装所需的 python 工具
sudo apt-get install python-catkin-tools python-rosinstall-generator -y
   
# 安装 mavlink
rosinstall_generator --rosdistro kinetic mavlink | tee /tmp/mavros.rosinstall
   
# 安装 mavros
rosinstall_generator --upstream-development mavros | tee -a /tmp/mavros.rosinstall
# 上面两步需要打开代理
   
# 创建 deps
wstool merge -t src /tmp/mavros.rosinstall	#这一步会报错 TypeError: load() missing 1 required positional argument: 'Loader'，需要修改 /usr/lib/python3/dist-packages/wstool/config_yaml.py 中 74 行为 yamldata = yaml.load(stream, Loader=yaml.FullLoader)
wstool update -t src -j4	#这一步需要关闭代理
rosdep install --from-paths src --ignore-src -y
   
# 安装GeographicLib
sudo ./src/mavros/mavros/scripts/install_geographiclib_datasets.sh
   
# build
catkin build
   
# 更新环境变量
source devel/setup.bash

  4. 编写 offboard 文件：

    # 建立 offboard 包，依赖于 roscpp mavros geometry_msgs
cd catkin_ws/src
catkin_create_pkg offboard roscpp mavros geometry_msgs
   
# 新建 cpp 文件，将官网提供的例程复制进去：https://docs.px4.io/main/zh/ros/mavros_offboard_cpp.html
cd offboard/src
gedit offb_node.cpp

    修改 CMakeList.txt 文件，需要修改 3 处：

    ###################################
## catkin specific configuration ##
###################################
## The catkin_package macro generates cmake config files for your package
## Declare things to be passed to dependent projects
## INCLUDE_DIRS: uncomment this if your package contains header files
## LIBRARIES: libraries you create in this project that dependent projects also need
## CATKIN_DEPENDS: catkin_packages dependent projects also need
## DEPENDS: system dependencies of this project that dependent projects also need
catkin_package(
 INCLUDE_DIRS include
#  LIBRARIES offboard
 CATKIN_DEPENDS geometry_msgs mavros roscpp
 DEPENDS system_lib
)
   
## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
add_executable(offb_node src/offb_node.cpp)
   
## Specify libraries to link a library or executable target against
target_link_libraries(offb_node
  ${catkin_LIBRARIES}
)

  5. 新建终端，回到catkin_ws工作区：

    cd catkin_ws
catkin build
source devel/setup.bash

  6. 运行，记得每个终端都要source devel/setup.bash：

    # 打开一个新终端，启动 gazebo
cd PX4-Autopilot
make px4_sitl_default gazebo
# 根据错误提示安装缺少的依赖，此处安装了 3 个
pip3 install kconfiglib
pip3 install --user jsonschema
pip3 install future
   
# 打开一个新终端，运行 mavros，连接到本地 ROS
roslaunch mavros px4.launch fcu_url:="udp://:14540@127.0.0.1:14557"
   
# 打开一个新终端，运行 offboard 实例
rosrun offboard offb_node

  7. 通过发布消息实现控制

    # body frame 下的控制，设置 velocity 和 yaw_rate 字段来分别控制无人机的线速度和角速度
rostopic pub -r 20 /mavros/setpoint_raw/local mavros_msgs/PositionTarget "{
header: { frame_id: 'base_footprint' },
coordinate_frame: 1,
type_mask: 4088,
position: { x: 0.0, y: 10.0, z: 12.0 },
velocity: { x: 0.0, y: 0.0, z: 0.0 },
acceleration_or_force: { x: 0.0, y: 0.0, z: 0.0 },
yaw: 0.0,
yaw_rate: 0.0
}"
   
# 设置线速度和角速度控制
rostopic pub -r 20 /mavros/setpoint_velocity/cmd_vel_unstamped geometry_msgs/Twist "linear:
  x: 1.0
  y: 0.0
  z: 0.0
angular:
  x: 0.0
  y: 0.0
  z: 0.5"