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Choreo

Choreo is the tool we draw autonomous paths with. You place waypoints on the field, Choreo generates the fastest trajectory the robot can physically follow between them, and the robot replays that trajectory in autonomous. Behavior-tree autos drive a path by name with the FollowTrajectory node, so Choreo and Arbor together are the whole autonomous workflow: Choreo for where, Arbor for what and when.

The Project​

The robot project holds one Choreo project file (.chor) and the generated trajectories in src/main/deploy/choreo/*.traj. Open the .chor from the robot project so the .traj files land in the right place.

Project settings that have to be right before anything else:

  • Drive type: Swerve for the competition robot, Differential for the lesson robots.
  • Robot measurements: mass, moment of inertia, wheel radius, track/module positions, motor and current limit. A path generated with the wrong numbers is one the real robot cannot follow on time. The 2026 robot's values are in the Choreo project already; a new robot copies them from CAD and the drivetrain constants.
  • Bumper size, so keep-out zones and wall clearance are honest.

Drawing a Path​

  1. New trajectory, give it the name the auto will use (SynergyP1, ToPickup). The name is the file name and what an auto's FollowTrajectory node names in its trajectory port, so pick it once and keep it.
  2. Place the start pose where the robot sits at the start of the auto (or where the previous path ended), add translation waypoints to shape the path, and finish on a pose waypoint so the heading at the end is defined.
  3. Add constraints where you need them: a maximum velocity near a pickup, stop points, keep-in or keep-out regions.
  4. Event markers mark a time along the path ("Intake Out"). The auto reacts to them with WaitForChoreoEvent or the IntakeOnEvent sub-tree, so the intake drops exactly where the path reaches the game piece.
  5. Generate. Look at the velocity graph: a path that saturates the whole way is as fast as it can be; one with sharp spikes usually wants a smoother waypoint.

Draw every path for the blue alliance. The robot flips trajectories for red automatically when the auto is selected, so there is one set of paths to maintain.

Using It From an Auto​

In Arbor, add a FollowTrajectory node to the auto and set its trajectory port to the path's name (SynergyP1). That is all the robot code needs. ./gradlew test in the robot project fails if an auto names a trajectory that has no .traj file, so a renamed path shows up before it reaches the robot. See Autonomous: Driving Paths for events and heading lock.

  • Autonomous: the autos that follow these paths.
  • Arbor: the editor for those autos.
  • Swerve: the CHOREO_* states and following gains.