Drone MAVSDK

Base controller, exposing a ROS2 interface to the PX4 flight controller using the MAVSDK library to control a drone in local flight. This node depends on the drone_interfaces package.

Coordinate Systems

Drone node

PX4 uses a NED coordinate system, and ROS2 uses an ENU coodinate system. This node publishes odometry in the odom_ned frame, and publishes an odom_ned -> base_link_ned transform. A static transform broadcaster is needed to publish a map->odom_ned transform, effectively flipping and rotating NED into ENU.

Frame Broadcaser

A second node is included that is timer driven. It looks up a transform from base_link_ned to odom, and publishes a transform from odom to base_link. This node needs a map->odom static transform broadcaster.

The static transform broadcasters are defined in the launch file. This completes the tree in line with ROS-REP 105. All unit and coordinate conventions in this node are compliant to ROS-REP 103.

Node Info

xxx@simulator:~/ros_ws$ ros2 node info /drone_node
/drone_node
  Subscribers:
    /drone/cmd_vel: geometry_msgs/msg/Twist
  Publishers:
    /drone/battery: sensor_msgs/msg/BatteryState
    /drone/gps: sensor_msgs/msg/NavSatFix
    /drone/odom: nav_msgs/msg/Odometry
    /tf: tf2_msgs/msg/TFMessage
  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:
  

Status

Test scripts run 100% in a simulator environment. The code is stable. Compiles on a Raspberry Pi 3 and 4, and connects successfully to a Pixhawk 4 Mini.

First test flights on an actual drone using a Pixhawk 4.0 Mini were good. The code seems flight ready.

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: 1}"

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}}"