Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/spectrum3847/2026-Spectrum/llms.txt

Use this file to discover all available pages before exploring further.

The Swerve subsystem extends CTRE’s SwerveDrivetrain class and integrates field-centric driving, autonomous path following, zone-based triggers, and pose estimation into a single command-based subsystem. Each of the four swerve modules is powered by a Kraken X60 FOC drive motor and a Kraken X60 FOC steer motor, communicating over the CANIVORE bus via Phoenix 6.

​
Hardware and initialization

Swerve is constructed with a SwerveConfig that carries drivetrain constants, module positions, and PID gains. During construction the robot seeds its pose to the field center, configures PathPlanner, and starts a high-rate simulation notifier when running in simulation.
Swerve.java
public Swerve(SwerveConfig config) {
    super(
            TalonFX::new,
            TalonFX::new,
            CANcoder::new,
            config.getDrivetrainConstants(),
            250.0,
            MapleSimSwerveDrivetrain.regulateModuleConstantsForSimulation(config.getModules()));
    ...
    configurePathPlanner();
}
The simulation thread runs at a faster rate than the main robot loop so that PID gains behave correctly in MapleSimSwerveDrivetrain.

​
Drive requests

SwerveStates pre-configures four CTRE swerve requests that are reused across all commands:
RequestUsage
SwerveRequest.FieldCentricNormal field-centric teleop driving
SwerveRequest.RobotCentricRobot-centric / FPV driving
SwerveRequest.SwerveDriveBrakeX-brake lock during launch
SwerveRequest.FieldCentricFacingAngleAim-assist rotation toward a target
SwerveStates.java
private static final SwerveRequest.FieldCentricFacingAngle FIELD_CENTRIC_FACING_ANGLE =
        new SwerveRequest.FieldCentricFacingAngle()
                .withDriveRequestType(DriveRequestType.Velocity)
                .withSteerRequestType(SteerRequestType.Position)
                .withMaxAbsRotationalRate(config.getMaxAngularRate())
                .withHeadingPID(
                        config.getKPRotationController(),
                        config.getKIRotationController(),
                        config.getKDRotationController());

​
Driver control bindings

The default command is pilotDrive, which maps the left stick to translation and the right stick to rotation. When the robot is in a LAUNCH_WITH_SQUEEZE, LAUNCH_WITHOUT_SQUEEZE, or TRACK_TARGET state the swerve automatically switches to pilotAimAtTarget, rotating the chassis toward the shot angle calculated by ShotCalculator. Alliance color is accounted for — the blue-alliance version adds 180° to the drive angle.
SwerveStates.java
(launching.or(launchPreping))
        .and(isRed, Util.autoMode.not())
        .whileTrue(log(pilotAimAtTargetRed()));
(launching.or(launchPreping))
        .and(isRed.not(), Util.autoMode.not())
        .whileTrue(log(pilotAimAtTargetBlue()));
launching.and(Robot.getPilot().RB).whileTrue(log(xBrake()));
Cardinal reorientation is available on the D-pad (upReorient, leftReorient, downReorient, rightReorient) and snaps the gyro heading without affecting translation.

​
Zone-based field positioning triggers

Swerve exposes two high-level zone Triggers used by RobotStates to gate mechanism behavior:
Returns true when the robot is inside the neutral (center) zone of the REBUILT field. The zone is a Rectangle2d centered at mid-field with a depth of 283 in and length of 317.7 in.
Swerve.java
public Trigger inNeutralZone() {
    final double fieldLengthMeters = Units.feetToMeters(54.0);
    final double fieldWidthMeters = Units.feetToMeters(27.0);
    final double neutralDepthMeters = Units.inchesToMeters(283.0);
    final double neutralLengthMeters = Units.inchesToMeters(317.7);
    final double centerX = fieldLengthMeters / 2.0;
    final double centerY = fieldWidthMeters / 2.0;
    Rectangle2d neutralZone = new Rectangle2d(
            new Translation2d(centerX - neutralDepthMeters / 2.0,
                              centerY - neutralLengthMeters / 2.0),
            new Translation2d(centerX + neutralDepthMeters / 2.0,
                              centerY + neutralLengthMeters / 2.0));
    return new Trigger(() -> neutralZone.contains(
            new Translation2d(getRobotPose().getX(), getRobotPose().getY())));
}
Returns true when the alliance-flipped X coordinate of the robot is inside the opponent’s alliance zone (the last 180 in of the field). FieldHelpers.flipXifRed handles the Blue/Red mirroring automatically.
Swerve.java
public Trigger inEnemyAllianceZone() {
    final double allianceDepthMeters = Units.inchesToMeters(180.0);
    ...
    return new Trigger(() -> enemyAllianceZone.contains(
            new Translation2d(FieldHelpers.flipXifRed(getRobotPose().getX()),
                              getRobotPose().getY())));
}
SwerveStates exposes these as public static helpers so RobotStates can compose them without depending directly on the Swerve instance:
SwerveStates.java
public static Trigger robotInNeutralZone() {
    return swerve.inNeutralZone();
}

public static Trigger robotInEnemyZone() {
    return swerve.inEnemyAllianceZone();
}

​
Pose estimation and odometry

Pose is read from getState().Pose (provided by the Phoenix SwerveDrivetrain base class), which fuses wheel odometry with vision measurements added externally by the Vision subsystem. In simulation the pose comes from the MapleSimSwerveDrivetrain physics model instead. getPoseAtTimestamp uses Phoenix’s built-in pose buffer to interpolate historical poses for latency-compensated vision updates.

​
PathPlanner integration

AutoBuilder.configure registers the swerve as the path-following subsystem. Translation is controlled by a PPHolonomicDriveController with separate PID constants (P=4 for translation, P=3 for rotation). The AutoRequest uses DriveRequestType.Velocity and desaturates wheel speeds to handle high-speed autonomous segments.

SwerveStates source

Trigger bindings and all drive command factories.

Swerve source

Zone triggers, pose methods, and PathPlanner configuration.

Build docs developers (and LLMs) love

Get started for freeTalk to us