Trajectories¶

Documentation / Controllers / Trajectories

The shared trajectory configuration is:

ros2/src/offboard_controllers/config/trajectory/trajectories.yaml

It is used by both the independent Offboard position controller and the SE(3) controller.

Coordinate convention¶

Trajectory references use PX4 local NED coordinates:

x: North
y: East
z: Down

Therefore an upward displacement has a negative z offset.

Anchoring and time origin¶

A configured trajectory is anchored to the vehicle position when PX4 confirms Offboard entry.

During prestream, the reference remains at trajectory time t = 0 and follows the current local position. The trajectory does not start advancing merely because the controller process started or because it requested Offboard.

If SE(3) loses Offboard and later regains confirmed ownership, it re-anchors and restarts the trajectory.

Segment semantics¶

Supported segment types currently include:

hold
step
line
circle
helix
yaw
figure_eight

Units in the YAML are:

duration                 seconds
offset/radius/height     metres
amplitude                 metres
yaw/yaw_offset            radians
turns                     revolutions

At an exact segment boundary, the segment that is ending owns that sample; the next segment begins immediately afterward. After the final segment, the terminal position/yaw is held indefinitely.

Checked-in trajectories¶

The current named trajectories are:

hover
step_response
line_tracking
circle_tracking
helix_tracking
translation_yaw_sweep
figure_eight_tracking
full_excitation

Use a name directly as a launch argument:

ros2 launch offboard_controllers offboard_position.launch.py \
  trajectory:=line_tracking

or:

ros2 launch offboard_controllers se3.launch.py \
  vehicle:=gz_f450 \
  trajectory:=figure_eight_tracking \
  handoff:=acceleration

Extending¶

To add new segments or named trajectories, follow Extending the toolkit.

Analysis relationship¶

px4_compare --trajectory <name> resolves this same configuration so it can compute segment-aware metrics against the configured maneuver boundaries.