Drone RTPS

A ROS2 node that interfaces to PX4 using Fast RTPS and published enough to get the navigation stack running. This thing runs in the Gazebo simulator, but I have not bable to test it against a flight controller yet. This is planned for September 2021

WARNING

This node has fallen a bit behind the Drone_MAVSDK version, and will not work with the Navigation Light Package at this stage. To bring it up to date, add:

• a map->odom transfom publisher,
• battery state publisher
• subscrive to the downward pointing range sensor and pass to flight controller
• gps position publisher (optional) Consult with the drone_mavsdk package for examples of how this is done. This is a valid starting point though.

Dependencies

This node depends on the drone_interfaces package.

Coordinate Systems

PX4 uses a Foreward Right Down coordinate system, and ROS2 uses a Foreward Left Up coodinate system. To align the two, a static transform boradcaster has to be started. This is demonstrated in the launch file.

node info

eric@simulator:~/ros_ws$ ros2 node info /drone_node
/drone_node
  Subscribers:
    /drone/cmd_vel: geometry_msgs/msg/Twist
  Publishers:
    /drone/odom: nav_msgs/msg/Odometry
  Service Servers:
    /drone/arm: drone_interfaces/srv/Arm
    /drone/offboard: drone_interfaces/srv/Offboard
  Service Clients:  
  
  Action Servers:
    /drone/land: drone_interfaces/action/Land
    /drone/takeoff: drone_interfaces/action/Takeoff
  Action Clients:
  
eric@simulator:~/ros_ws$

Status

• The code compiles and runs on a Virtual Box machine running Ubuntu 20.04 LTS
• The code compiles and runs on a Raspberry Pi 4 4Mb running Ubuntu 20.04 LTS
• Code needs to be tested in the smulator (functional testing)
• Code neets to be tested against a real flight controller (Pixhawk 4 Mini)

Test Scripts

Arm the drone

ros2 service call /drone/arm drone_interfaces/srv/Arm

Takeoff

ros2 action send_goal /drone/takeoff "drone_interfaces/action/Takeoff" "{target_altitude: 5.0}"

Land

ros2 action send_goal /drone/land "drone_interfaces/action/Land" "{gear_down: true}"

Enable offboard mode

ros2 service call /drone/offboard drone_interfaces/srv/Offboard "{enable: 0}"

Fly in a circle

ros2 topic pub --once /drone/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 2.0, y: 0.0, z: 0.5}, angular: {x: 0.0, y: 0.0, z: 0.5}}"

Caution

This code has not flown.