ardupilot_gazebo仿真（三）

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创建ROS node 实现对无人机的控制(软件在环)

MAVROS

MAVROS是ROS中的一个能够连接支持MAVLink地面站、支持MAVLink飞控和ROS计算机的工具。

安装MAVROS

sudo apt-get install ros-kinetic-mavros ros-kinetic-mavros-extras
wget https://raw.githubusercontent.com/mavlink/mavros/master/mavros/scripts/install_geographiclib_datasets.sh
chmod a+x install_geographiclib_datasets.sh
./install_geographiclib_datasets.sh

推荐安装rqt

sudo apt-get install ros-kinetic-rqt ros-kinetic-rqt-common-plugins ros-kinetic-rqt-robot-plugins

创建外部控制包

外部控制程序中文介绍
根据ROS官网教程，创建一个ROS包

cd ~/catkin_ws/src
catkin_create_pkg offboard roscpp mavros geometry_msgs

这时会在catkin_ws/src目录中生成offboard文件夹，其中包含include和src两个文件夹。我们将offboard_node.cpp放在刚刚生成的offboard/src中。修改offboard目录下的CMakeLists.txt文件，取消一些注释生成相应节点。

    ## 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(${PROJECT_NAME}_node src/offboard_node.cpp)
    
    ## Rename C++ executable without prefix
    ## The above recommended prefix causes long target names, the following renames the
    ## target back to the shorter version for ease of user use
    ## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
    # set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")
    
    ## Add cmake target dependencies of the executable
    ## same as for the library above
    # add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})
    
    ## Specify libraries to link a library or executable target against
     target_link_libraries(${PROJECT_NAME}_node
       ${catkin_LIBRARIES}
     )

offboard_node.cpp是我们创建的节点的名字。

然后在catkin_ws中，进行编译

cd ~/catkin_ws
catkin_make
source devel/setup.bash

每次要运行节点是都要source setup.bash

启动仿真

01.启动地面站MAVproxy

cd ardupilot/ArduCopter
sim_vehicle.py --map --console

02.launch MAVROS

roslaunch mavros apm.launch

03.运行自己做的外部程序节点

cd catkin_ws/
source devel/setup.bash
rosrun offboard offboard_node

利用graph实时绘制曲线

graph是MAVproxy的一个module
用之前先要load graph

module load graph

常用参数监视

graph NAV_CONTROLLER_OUTPUT.nav_roll ATTITUDE.roll*57.32
graph NAV_CONTROLLER_OUTPUT.nav_pitch ATTITUDE.pitch*57.32
graph NAV_CONTROLLER_OUTPUT.nav_bearing ATTITUDE.yaw*57.32
graph VFR_HUD.alt 
graph VFR_HUD.climb

NAV_CONTROLLER_OUTPUT 是期望数据
ATTITUDE 姿态需要乘以57.32变成角度

VFR_HUD.airspeed     VFR_HUD.climb        VFR_HUD.heading
VFR_HUD.alt          VFR_HUD.groundspeed  VFR_HUD.throttle

MAVprovxy控制无人机的指令

参考MAVproxy教程，官网给出了较完整的命令集
这里只做最简单的介绍，可以让无人机飞起来。

mode guided
arm throttle
takeoff 40

其中一些飞行模式需要rc 3 在中立的位置，例如alt_hold loiter circle 模式等

rc 3 1500

在地面站还可以对参数进行设置

GUIDED> param show fence*
GUIDED> FENCE_ACTION     1.000000
FENCE_ALT_MAX    100.000000
FENCE_ENABLE     0.000000
FENCE_MARGIN     2.000000
FENCE_RADIUS     150.000000
FENCE_TYPE       3.000000