Set up PathPlanner

Register a YAGSL-built SwerveDrive with PathPlanner's AutoBuilder.

PathPlanner is a separate tool from YAGSL — it plans and follows multi-point paths (with obstacle-aware routing, event markers, and an on-field GUI editor) rather than the single point-to-point moves in driveToPose. This page wires a YAGSL-built SwerveDrive into it. It assumes you already have a driving robot from the Tutorial.

This page covers the YAGSL/YAMS side of the wiring. For building paths/autos themselves, installing the standalone PathPlanner GUI app, and general PathPlanner concepts, see PathPlanner's own documentation.

1. Install PathplannerLib

Open the WPILib Vendor Dependencies panel in VS Code (same place you installed YAGSL — see Install YAGSL) and install PathplannerLib from the catalog.

2. Export your robot config from the PathPlanner GUI

In the PathPlanner GUI app, fill in your robot's mass, MOI, module offsets, wheel radius, and drive motor specs under its Robot Config tab, then export. This writes deploy/pathplanner/settings.json, which RobotConfig.fromGUISettings() reads at runtime — you don't hand-write this file or duplicate its values in Java.

This is a second, separate description of your robot's physical properties from YAGSL's own modules/physicalproperties.json — gear ratio and wheel diameter in particular exist in both places. If you change one (a wheel swap, a gearing change), update the other too, or PathPlanner's paths and YAGSL's own odometry will disagree about how far the robot actually travels. This is a common, JSON-invisible cause of drift — see the PathPlanner section of Swerve Drive Drift.

3. Register AutoBuilder once, right after building the drive

Do this once, in your swerve subsystem's constructor, right after SwerveParser.createSwerveDrive(...) returns. After this call, PathPlannerAuto commands and GUI-defined paths just work — no extra wiring per auto.

import com.pathplanner.lib.auto.AutoBuilder;
import com.pathplanner.lib.config.PIDConstants;
import com.pathplanner.lib.config.RobotConfig;
import com.pathplanner.lib.controllers.PPHolonomicDriveController;
import edu.wpi.first.wpilibj.DriverStation;
import java.io.IOException;
import org.json.simple.parser.ParseException;

public class SwerveDriveSubsystem extends SubsystemBase {
  private SwerveDrive drive;

  public SwerveDriveSubsystem() {
    var cfg = new SwerveDriveConfig()
        .withStartingPose(new Pose2d(3, 3, Rotation2d.kZero))
        .withSubsystem(this)
        .withTelemetry(TelemetryVerbosity.HIGH);

    drive = new SwerveParser(new File(Filesystem.getDeployDirectory(), "swerve/base"))
        .createSwerveDrive(cfg);

    try {
      setupPathPlanner();
    } catch (IOException | ParseException e) {
      throw new RuntimeException(
          "PathPlanner setup failed -- check deploy/pathplanner/settings.json exists", e);
    }
  }

  private void setupPathPlanner() throws IOException, ParseException {
    AutoBuilder.configure(
        drive::getPose,                  // robot pose supplier
        drive::resetOdometry,             // called if an auto defines a starting pose
        drive::getRobotRelativeSpeed,     // ChassisSpeeds supplier -- MUST be robot-relative
        (speedsRobotRelative, moduleFeedForwards) ->
            drive.setRobotRelativeChassisSpeeds(speedsRobotRelative),
        new PPHolonomicDriveController(
            new PIDConstants(5.0, 0.0, 0.0),  // translation PID
            new PIDConstants(5.0, 0.0, 0.0)   // rotation PID
        ),
        RobotConfig.fromGUISettings(),    // reads deploy/pathplanner/settings.json
        () -> {
          // Field origin is always the blue alliance wall -- flip paths when on red.
          var alliance = DriverStation.getAlliance();
          return alliance.filter(a -> a == DriverStation.Alliance.Red).isPresent();
        },
        this                              // subsystem requirement for the generated commands
    );
  }
}

The PPHolonomicDriveController PID constants above are independent of SwerveDriveConfig.withTranslationController()/withRotationController() from driveToPose — PathPlanner's AutoBuilder uses its own controller and never touches YAGSL's. Tune them separately; there's no reason they need matching gains.

4. Run an auto

public Command getAutonomousCommand() {
  return new PathPlannerAuto("New Auto");
}

Build "New Auto" in the PathPlanner GUI, deploy, and bind getAutonomousCommand() the same way you'd bind any other autonomous command (RobotContainer's autonomous command supplier, or Robot.autonomousInit()). Event markers placed in the GUI fire EventTriggers in code:

new EventTrigger("EventMarker").whileTrue(Commands.print("Something"));

Troubleshooting

If a PathPlanner auto drives the wrong distance, curves when it should be straight, or ends up in the wrong spot, see the PathPlanner checklist in Swerve Drive Drift before re-tuning anything — most of these trace back to the config mismatch in step 2, or PID gains that were never tuned past their defaults.