Alpha vs Competition bot configuration

REBUILT 2026 runs on two physical robots — an Alpha prototype used for early development and testing, and a Competition bot used at events. The codebase targets both from a single source tree: hardware-specific constants (PID gains, gear ratios, soft limits, CAN bus routing, and camera transforms) branch automatically at startup based on which robot the code is running on. In simulation the type is always SIM.

How robot type is detected

RobotType.java contains a static initializer that runs exactly once when the class is first loaded — before any subsystem is constructed:

public class RobotType {
  private static final String comp  = "032B4B39"; // Comp bot serial number
  private static final String alpha = "032B4B88"; // Alpha bot serial number

  public static final RobotTypesEnum TYPE;

  static {
    if (RobotBase.isSimulation()) {
      TYPE = RobotTypesEnum.SIM;
    } else {
      String serialNumber = RobotController.getSerialNumber();
      if (serialNumber.equals(comp)) {
        TYPE = RobotTypesEnum.COMP;
        DataLogManager.log("Running on Comp-bot");
      } else if (serialNumber.equals(alpha)) {
        TYPE = RobotTypesEnum.ALPHA;
        DataLogManager.log("Running on Alpha-bot");
      } else {
        TYPE = RobotTypesEnum.OTHER;
        DataLogManager.log("Unknown robot detected serial number is " + serialNumber);
      }
    }
  }

  public static boolean isAlpha() { return TYPE == RobotTypesEnum.ALPHA; }
  public static boolean isComp()  { return TYPE == RobotTypesEnum.COMP; }
  public static boolean isSim()   { return TYPE == RobotTypesEnum.SIM; }
}

RobotController.getSerialNumber() reads the RoboRIO’s hardware serial number from the FPGA. Because TYPE is a public static final field, every class that imports RobotType sees the same resolved value for the entire robot session.

In simulation, RobotBase.isSimulation() returns true before the serial number branch is ever reached, so TYPE is always RobotTypesEnum.SIM regardless of any environment configuration.

The full enum is:

public enum RobotTypesEnum {
  COMP,   // Competition bot — serial "032B4B39"
  ALPHA,  // Alpha prototype — serial "032B4B88"
  SIM,    // WPILib simulation environment
  OTHER   // Unknown RoboRIO — logs the serial number and continues
}

Drivetrain configuration

The drivebase is the most significant branching point. In Subsystems.java:

if (DRIVEBASE_ENABLED) {
  drivebaseSubsystem =
      (RobotType.TYPE == RobotTypesEnum.ALPHA)
          ? AlphaTunerConstants.createDrivetrain()
          : CompTunerConstants.createDrivetrain();
}

MaxSpeed in Controls.java follows the same pattern:

public static final double MaxSpeed =
    (RobotType.TYPE == RobotTypesEnum.ALPHA)
        ? AlphaTunerConstants.kSpeedAt12Volts.in(MetersPerSecond)
        : CompTunerConstants.kSpeedAt12Volts.in(MetersPerSecond);

Alpha bot
Competition bot

AlphaTunerConstants — generated by Tuner X for the Alpha prototype.

Parameter	Value
Top speed at 12 V	5.48 m/s
Drive gear ratio	5.357 : 1
Steer gear ratio	18.75 : 1
Wheel radius	1.84 in
CAN bus name	`"Drivebase"` (CANivore)
Slip current	120 A
Drive supply current limit	(none — default `TalonFXConfiguration`)
Stator current limit (steer)	60 A
Steer kV	2.33 V / (rot/s)
Module positions (FL, FR, BL, BR)	±12.375 in × ±10.5 in

CompTunerConstants — generated by Tuner X 2026 for the Competition bot.

Parameter	Value
Top speed at 12 V	5.30 m/s
Drive gear ratio	5.357 : 1
Steer gear ratio	18.75 : 1
Wheel radius	1.924 in
CAN bus name	`"Drivebase"` (Phoenix 6 CANivore named `"Drivebase"`)
Slip current	80 A
Drive supply current limit	80 A upper / 40 A lower for 2 s
Drive stator current limit	80 A
Stator current limit (steer)	60 A
Steer kV	1.79 V / (rot/s)
Module positions (FL, FR, BL, BR)	±9.375 in × ±12.375 in

Turret configuration

TurretSubsystem branches on RobotType.isAlpha() for PID gains, gear ratio, soft limits, and CAN bus:

private static final double kP = RobotType.isAlpha() ? 25  : 200;
private static final double kD = RobotType.isAlpha() ? 0   : 2;
private static final double kS = RobotType.isAlpha() ? 0.41 : 0.65;

private static final double GEAR_RATIO = RobotType.isAlpha() ? 24 : 40;

public static final double TURRET_MAX = RobotType.isAlpha() ? 190 : 350; // degrees
public static final double TURRET_MIN = RobotType.isAlpha() ? 0   : -90; // degrees

The turret motor CAN bus also differs:

turretMotor = new TalonFX(
    Hardware.TURRET_MOTOR_ID,
    RobotType.isAlpha() ? CANBus.roboRIO() : CompTunerConstants.kCANBus);

Alpha bot
Competition bot

Parameter	Value
kP	25
kI	0
kD	0
kS	0.41 V
Gear ratio	24 : 1
Forward soft limit	190°
Reverse soft limit	0°
CAN bus	`CANBus.roboRIO()`

Parameter	Value
kP	200
kI	0
kD	2
kS	0.65 V
Gear ratio	40 : 1
Forward soft limit	350°
Reverse soft limit	-90°
CAN bus	`CompTunerConstants.kCANBus` (`"Drivebase"` CANivore)

Both robots share the same stator and supply current limits (40 A each) and the same motor ID (Hardware.TURRET_MOTOR_ID = 23).

Vision camera transforms

VisionSubsystem defines three Transform3d constants that describe where each Limelight camera is mounted on the Competition bot relative to the robot origin. The Alpha bot uses a separate velocity-gating path (see below).

public static final Transform3d COMP_BOT_LEFT_CAMERA =
    new Transform3d(-0.076, 0.311, 0.274,
        new Rotation3d(0, toRadians(-20), toRadians(90)));

public static final Transform3d COMP_BOT_FRONT_CAMERA =
    new Transform3d(0.295, -0.288, 0.273,
        new Rotation3d(0, toRadians(-20), 0));

public static final Transform3d COMP_BOT_RIGHT_CAMERA =
    new Transform3d(0.212, -0.371, 0.273,
        new Rotation3d(0, toRadians(-20), toRadians(-90)));

All three cameras pitch down at −20°. Left and right cameras rotate ±90° in yaw; the front camera faces forward. The Alpha bot applies stricter velocity gating — vision updates are rejected if any chassis speed axis exceeds 2.0 m/s or if angular velocity exceeds 0.2 rad/s:

if (RobotType.isAlpha() &&
    (Math.abs(speeds.vxMetersPerSecond) > MAX_XY_VELO_ALPHA ||
     Math.abs(speeds.vyMetersPerSecond) > MAX_XY_VELO_ALPHA ||
     Math.abs(speeds.omegaRadiansPerSecond) > MAX_TURN_VELO_ALPHA)) {
  // reject update — "alpha-max-speed"
}

Additionally, target count for getNumTargets() is reported differently: the Alpha bot uses only CCamera (Limelight C), while the Comp bot sums ACamera and BCamera.

Summary comparison

Property	Alpha	Competition
RoboRIO serial	`032B4B88`	`032B4B39`
Top drivetrain speed	5.48 m/s	5.30 m/s
Wheel radius	1.84 in	1.924 in
Swerve module footprint	12.375 × 10.5 in	9.375 × 12.375 in
Turret kP	25	200
Turret kD	0	2
Turret kS	0.41 V	0.65 V
Turret gear ratio	24 : 1	40 : 1
Turret travel	0° – 190°	−90° – 350°
Turret CAN bus	roboRIO	CANivore `"Drivebase"`
Vision velocity gate	2.0 m/s / 0.2 rad/s	none
Primary vision cameras	Limelight C	Limelight A + B

Get Started

Subsystems

Autonomous

Simulation

Configuration & Tuning

Alpha vs Competition bot configuration

How robot type is detected

Drivetrain configuration

Turret configuration

Vision camera transforms

Summary comparison

Build docs developers (and LLMs) love

Get Started

Subsystems

Autonomous

Simulation

Configuration & Tuning

Documentation Index

​How robot type is detected

​Drivetrain configuration

​Turret configuration

​Vision camera transforms

​Summary comparison

Build docs developers (and LLMs) love

How robot type is detected

Drivetrain configuration

Turret configuration

Vision camera transforms

Summary comparison