airsim_ros_pkgs#

AirSim C++客户端库上的ROS封装。

安装#

以下步骤适用于Linux。如果在Windows上运行AirSim，则可以使用Windows Subsystem for Linux（WSL）来运行ROS包装，请参阅下面的说明。如果由于某些问题，您无法或不喜欢在主机Linux上安装ROS和相关工具，您也可以使用Docker尝试，请参阅为 ROS 封装使用 Docker 中的步骤

如果默认GCC版本不是8或更高版本（使用GCC--version检查）
- 使用 gcc >= 8.0.0: sudo apt-get install gcc-8 g++-8
- 使用 gcc-8 --version 验证安装
Ubuntu 16.04
- 安装 ROS kinetic
- 安装tf2 sensor 和 mavros 包：sudo apt-get install ros-kinetic-tf2-sensor-msgs ros-kinetic-tf2-geometry-msgs ros-kinetic-mavros*
Ubuntu 18.04
- 安装 ROS melodic
- 安装 tf2 sensor 和 mavros 包: sudo apt-get install ros-melodic-tf2-sensor-msgs ros-melodic-tf2-geometry-msgs ros-melodic-mavros*
Ubuntu 20.04
- 安装 ROS noetic
- 安装 tf2 sensor 和 mavros 包: sudo apt-get install ros-noetic-tf2-sensor-msgs ros-noetic-tf2-geometry-msgs ros-noetic-mavros*
安装 catkin_tools sudo apt-get install python-catkin-tools 或 pip install catkin_tools。如果在 Ubuntu 20.04 则使用 pip install "git+https://github.com/catkin/catkin_tools.git#egg=catkin_tools"

构建#

构建 AirSim

git clone https://github.com/Microsoft/AirSim.git;
cd AirSim;
./setup.sh;
./build.sh;

确保已按照上面的安装页面中所述设置ROS的环境变量。为方便起见，将source命令添加到.bashrc中（用特定的版本名替换mediatic）：

echo "source /opt/ros/melodic/setup.bash" >> ~/.bashrc
source ~/.bashrc

构建 ROS 包

cd ros;
catkin build; # 或 catkin_make

如果默认GCC不是8或更高（使用GCC--version检查），则编译将失败。在这种情况下，请显式使用gcc-8，如下所示

catkin build -DCMAKE_C_COMPILER=gcc-8 -DCMAKE_CXX_COMPILER=g++-8

运行#

source devel/setup.bash;
roslaunch airsim_ros_pkgs airsim_node.launch;
roslaunch airsim_ros_pkgs rviz.launch;

注意

如果在运行roslaunch airsim_ros_pkgs airsim_node.launch时出错，请运行catkin clean，然后重试

使用 AirSim ROS 包装器#

ROS包装器由两个ROS节点组成——第一个是AirSim多旋翼 C++ 客户端库的包装器，第二个是简单的比例-微分(PD) 位置控制器。让我们看看这 2 个节点的ROS API：

AirSim ROS 包装器节点#

发布者：#

/airsim_node/origin_geo_point airsim_ros_pkgs/GPSYaw GPS coordinates corresponding to global NED frame. This is set in the airsim's settings.json file under the OriginGeopoint key.
/airsim_node/VEHICLE_NAME/global_gps sensor_msgs/NavSatFix This the current GPS coordinates of the drone in airsim.
/airsim_node/VEHICLE_NAME/odom_local_ned nav_msgs/Odometry Odometry in NED frame (default name: odom_local_ned, launch name and frame type are configurable) wrt take-off point.
/airsim_node/VEHICLE_NAME/CAMERA_NAME/IMAGE_TYPE/camera_info sensor_msgs/CameraInfo
/airsim_node/VEHICLE_NAME/CAMERA_NAME/IMAGE_TYPE sensor_msgs/Image RGB or float image depending on image type requested in settings.json.
/tf tf2_msgs/TFMessage
/airsim_node/VEHICLE_NAME/altimeter/SENSOR_NAME airsim_ros_pkgs/Altimeter This the current altimeter reading for altitude, pressure, and QNH
/airsim_node/VEHICLE_NAME/imu/SENSOR_NAME sensor_msgs::Imu IMU sensor data
/airsim_node/VEHICLE_NAME/magnetometer/SENSOR_NAME sensor_msgs::MagneticField Meausrement of magnetic field vector/compass
/airsim_node/VEHICLE_NAME/distance/SENSOR_NAME sensor_msgs::Range Meausrement of distance from an active ranger, such as infrared or IR
/airsim_node/VEHICLE_NAME/lidar/SENSOR_NAME sensor_msgs::PointCloud2 LIDAR pointcloud

订阅者:#

/airsim_node/vel_cmd_body_frame airsim_ros_pkgs/VelCmd Ignore vehicle_name field, leave it to blank. We will use vehicle_name in future for multiple drones.
/airsim_node/vel_cmd_world_frame airsim_ros_pkgs/VelCmd Ignore vehicle_name field, leave it to blank. We will use vehicle_name in future for multiple drones.
/gimbal_angle_euler_cmd airsim_ros_pkgs/GimbalAngleEulerCmd Gimbal set point in euler angles.
/gimbal_angle_quat_cmd airsim_ros_pkgs/GimbalAngleQuatCmd Gimbal set point in quaternion.
/airsim_node/VEHICLE_NAME/car_cmd airsim_ros_pkgs/CarControls Throttle, brake, steering and gear selections for control. Both automatic and manual transmission control possible, see the car_joy.py script for use.

服务:#

/airsim_node/VEHICLE_NAME/land airsim_ros_pkgs/Takeoff
/airsim_node/takeoff airsim_ros_pkgs/Takeoff
/airsim_node/reset airsim_ros_pkgs/Reset Resets all drones

参数:#

/airsim_node/world_frame_id [string] Set in: $(airsim_ros_pkgs)/launch/airsim_node.launch Default: world_ned Set to "world_enu" to switch to ENU frames automatically
/airsim_node/odom_frame_id [string] Set in: $(airsim_ros_pkgs)/launch/airsim_node.launch Default: odom_local_ned If you set world_frame_id to "world_enu", the default odom name will instead default to "odom_local_enu"
/airsim_node/coordinate_system_enu [boolean] Set in: $(airsim_ros_pkgs)/launch/airsim_node.launch Default: false If you set world_frame_id to "world_enu", this setting will instead default to true
/airsim_node/update_airsim_control_every_n_sec [double] Set in: $(airsim_ros_pkgs)/launch/airsim_node.launch Default: 0.01 seconds. Timer callback frequency for updating drone odom and state from airsim, and sending in control commands. The current RPClib interface to unreal engine maxes out at 50 Hz. Timer callbacks in ROS run at maximum rate possible, so it's best to not touch this parameter.
/airsim_node/update_airsim_img_response_every_n_sec [double] Set in: $(airsim_ros_pkgs)/launch/airsim_node.launch Default: 0.01 seconds. Timer callback frequency for receiving images from all cameras in airsim. The speed will depend on number of images requested and their resolution. Timer callbacks in ROS run at maximum rate possible, so it's best to not touch this parameter.
/airsim_node/publish_clock [double] Set in: $(airsim_ros_pkgs)/launch/airsim_node.launch Default: false Will publish the ros /clock topic if set to true.

简单 PID 位置控制器节点#

参数:#

PD 控制器参数：
/pd_position_node/kd_x [double], /pd_position_node/kp_y [double], /pd_position_node/kp_z [double], /pd_position_node/kp_yaw [double] Proportional gains
/pd_position_node/kd_x [double], /pd_position_node/kd_y [double], /pd_position_node/kd_z [double], /pd_position_node/kd_yaw [double] Derivative gains
/pd_position_node/reached_thresh_xyz [double] Threshold euler distance (meters) from current position to setpoint position
/pd_position_node/reached_yaw_degrees [double] Threshold yaw distance (degrees) from current position to setpoint position
/pd_position_node/update_control_every_n_sec [double] Default: 0.01 seconds

服务:#

/airsim_node/VEHICLE_NAME/gps_goal [Request: srv/SetGPSPosition] Target gps position + yaw. In absolute altitude.
/airsim_node/VEHICLE_NAME/local_position_goal [Request: srv/SetLocalPosition] Target local position + yaw in global NED frame.

订阅者:#

/airsim_node/origin_geo_point airsim_ros_pkgs/GPSYaw Listens to home geo coordinates published by airsim_node.
/airsim_node/VEHICLE_NAME/odom_local_ned nav_msgs/Odometry Listens to odometry published by airsim_node

发布者:#

/vel_cmd_world_frame airsim_ros_pkgs/VelCmd Sends velocity command to airsim_node

全局参数#

Dynamic constraints. These can be changed in dynamic_constraints.launch:
- /max_vel_horz_abs [double] Maximum horizontal velocity of the drone (meters/second)
- /max_vel_vert_abs [double] Maximum vertical velocity of the drone (meters/second)
- /max_yaw_rate_degree [double] Maximum yaw rate (degrees/second)

杂项#

使用 WSL1 或 WSL2 在 Windows10 上设置构架环境#

这些安装说明描述了如何设置“Windows上Ubuntu上的Bash”（又名“Linux的Windows子系统”）。

它涉及在Windows10中启用内置的Windows Linux环境（WSL），安装兼容的Linux OS映像，最后安装构建环境，就像它是一个普通的Linux系统一样。

完成后，您将能够像在本机linux机器中一样构建和运行ros包装器。

WSL1 vs WSL2#

WSL2 is the latest version of the Windows10 Subsystem for Linux. It is many times faster than WSL1 (if you use the native file system in /home/... rather than Windows mounted folders under /mnt/...) and is therefore much preferred for building the code in terms of speed.

Once installed, you can switch between WSL1 or WSL2 versions as you prefer.

WSL Setup steps#

Follow the instructions here. Check that the ROS version you want to use is supported by the Ubuntu version you want to install.
Congratulations, you now have a working Ubuntu subsystem under Windows, you can now go to Ubuntu 16 / 18 instructions and then How to run Airsim on Windows and ROS wrapper on WSL!

Note

You can run XWindows applications (including SITL) by installing VcXsrv on Windows. To use it find and run XLaunch from the Windows start menu. Select Multiple Windows in first popup, Start no client in second popup, only Clipboard in third popup. Do not select Native Opengl (and if you are not able to connect select Disable access control). You will need to set the DISPLAY variable to point to your display: in WSL it is 127.0.0.1:0, in WSL2 it will be the ip address of the PC's network port and can be set by using the code below. Also in WSL2 you may have to disable the firewall for public networks, or create an exception in order for VcXsrv to communicate with WSL2:

export DISPLAY=$(cat /etc/resolv.conf | grep nameserver | awk '{print $2}'):0

Tip

If you add this line to your ~/.bashrc file you won't need to run this command again
For code editing you can install VSCode inside WSL.
Windows 10 includes "Windows Defender" virus scanner. It will slow down WSL quite a bit. Disabling it greatly improves disk performance but increases your risk to viruses so disable at your own risk. Here is one of many resources/videos that show you how to disable it: How to Disable or Enable Windows Defender on Windows 10

File System Access between WSL and Windows10#

From within WSL, the Windows drives are referenced in the /mnt directory. For example, in order to list documents within your () documents folder:

`ls /mnt/c/'Documents and Settings'/<username>/Documents`
or
`ls /mnt/c/Users/<username>/Documents`

From within Windows, the WSL distribution's files are located at (type in windows Explorer address bar):

\\wsl$\<distribution name> e.g. \\wsl$\Ubuntu-18.04

How to run Airsim on Windows and ROS wrapper on WSL#

For WSL 1 execute: export WSL_HOST_IP=127.0.0.1 and for WSL 2: export WSL_HOST_IP=$(cat /etc/resolv.conf | grep nameserver | awk '{print $2}') Now, as in the running section for linux, execute the following:

source devel/setup.bash
roslaunch airsim_ros_pkgs airsim_node.launch output:=screen host:=$WSL_HOST_IP
roslaunch airsim_ros_pkgs rviz.launch

Using Docker for ROS#

A Dockerfile is present in the tools directory. To build the airsim-ros image -

cd tools
docker build -t airsim-ros -f Dockerfile-ROS .

To run, replace the path of the AirSim folder below -

docker run --rm -it --net=host -v <your-AirSim-folder-path>:/home/testuser/AirSim airsim-ros:latest bash

The above command mounts the AirSim directory to the home directory inside the container. Any changes you make in the source files from your host will be visible inside the container, which is useful for development and testing. Now follow the steps from Build to compile and run the ROS wrapper.