Basic Flight Controller

The flight controller is responsible for passing high level position information to the pixhawk/pixracer. The controller is written in C++ and designed to be extended for multiple use cases. To develop your own controller see the controller development page.

This page will cover how to use the basic pose controller:

Usage

You’ll need to launch two sets of launch files on the quad via ssh.

ROS Bridge

roslaunch mslquad quad_vrpn.launch

This will create the connection between the roscore, motion capture, and the px4. You should verify that the quad ID in:

quad_vrpn.launch

is the same as the one you have in Motive e.g., for quad3 the ID=”3”.

Controller

roslaunch mslquad pose_controller.launch

This will launch the pose_controller node which allows you to set a goal point of the quad. You can directly publish to quad#/command/pose. You can also run:

roslaunch mslquad goal_set.launch

to use a python script to set the goal position. Make sure you change the namespace before using this launch file.

Troubleshooting

Things will likely break, this is here so you don’t break as well. The first you should do is restart everything on the quad and make sure everything is plugged in.

All the examples use “quad0”, change that to the quad that’s not working.

Verify all of the following

  • Serial Connection

    Verify all the serial connection wires are connected and not loose. To check if px4 is comunicating with ros run:

    rostopic echo quad0/mavros/state

    This should return a connected: TRUE. If not then check that fcu_url in quad_vrpn.launch is pointing to the correct port.

  • Motion Capture

    Verify that the motion capture and quad estimator poses match:

    rostopic echo quad0/mavros/vision_pose/pose
rostopic echo quad0/mavros/local_position/pose

ROS Parameters

Basic Parameters: You’ll find these in the pose_controller.launch file.

  • takeoff_height: float. (1.5)
    Takeoff height in m. Do not set this higher than 2
  • max_vel: float. (2.0)
    Maximum velocity in m/s. The flight room is small don’t go higher than 4 m/s
  • auto_takeoff: Boolean. (True)
    The quad will takeoff as soon as it’s armed. Stand back. Don’t be another statistic.

Pose Controller Parameters:

  • pose_target_topic: Rostopic Pose. (command/pose)
    Target pose of the quad.