Indexer subsystem: feeder and spindexer control

The indexer moves fuel from the intake staging area into the launcher using two motors: a Feeder that pushes fuel along the exit path, and a Spindexer that spins fuel into the feed zone. Both are wrapped by IndexerSubsystem, which exposes a single runIndexer() command used by the launching sequence.

Components

Feeder

Feeder drives a single TalonFX (CAN ID FEEDER_MOTOR_ID = 30) on the CANivore bus (comp bot) or roboRIO bus (alpha bot) using VelocityVoltage control.

Parameter	Value
Default target RPS	95 RPS
kV	`11.28 / 92`
kP	0.5
Stator limit	120 A
Supply limit	80 A
Neutral mode	Coast

Spindexer

Spindexer drives a single TalonFX (CAN ID SPINDEXER_MOTOR_ID = 31) on the roboRIO bus using VelocityVoltage control.

Parameter	Value
Default target RPS	70 RPS
Default acceleration	1000 rot/s²
kV	`11.2 / 90.7`
kP	0.6
Stator limit	50 A
Supply limit	30 A
Neutral mode	Coast

IndexerSubsystem API

IndexerSubsystem exposes two variants of runIndexer():

`runIndexer()` — fixed velocity

Runs both motors at their default configured velocities.

public Command runIndexer() {
    return Commands.runEnd(
            () -> {
                feeder.runVelocity();
                spindexerSubsystem.runVelocity();
            },
            () -> {
                feeder.stopMotor();
                spindexerSubsystem.stopMotor();
            })
        .withName("Run Indexer");
}

`runIndexer(DoubleSupplier flywheelRPS)` — flywheel-matched velocity

Scales feeder and spindexer velocity to match the active flywheel speed for a smooth handoff. The linear equations provide proportional ramping:

public Command runIndexer(DoubleSupplier flywheelRPS) {
    return Commands.runEnd(
        () -> {
            // Scale feeder and spindexer from flywheel speed for smooth handoff
            double fRPS = flywheelRPS.getAsDouble() * 1.12 + 15;
            double sRPS = Math.min(fRPS * 1.5, 70);
            feeder.setVelocity(fRPS);
            spindexerSubsystem.setVelocity(sRPS);
        },
        () -> {
            feeder.stopMotor();
            spindexerSubsystem.stopMotor();
        });
}

The spindexer is capped at 70 RPS regardless of flywheel speed to prevent over-spinning.

Launch integration

The indexer is gated behind launcherSubsystem.isAtTarget() in the launching command chain in Controls.java. Fuel is not fed until flywheels, hood, and turret are all within tolerance:

Commands.waitUntil(() -> s.launcherSubsystem.isAtTarget())
    .andThen(
        Commands.parallel(
            s.indexerSubsystem.runIndexer(() -> s.flywheels.getTargetSpeed()),
            Commands.runOnce(() -> ledsMode = LEDMode.LAUNCH))
        .onlyWhile(() -> s.launcherSubsystem.isAtTarget()))
    .repeatedly()

If the launcher drops out of tolerance mid-cycle (e.g. the robot is bumped), onlyWhile() cancels the indexer automatically and the loop waits for re-acquisition.

Controller binding

Controller	Button	Action
`indexingTestController` (port 1)	Left trigger	`whileTrue(runIndexer())` — runs at fixed default velocity

The indexer only instantiates if both SPINDEXER_ENABLED and FEEDER_ENABLED are true in Subsystems.java. Controls.java checks for null subsystems and logs a warning if either component is disabled, skipping all indexer bindings.

Get Started

Subsystems

Autonomous

Simulation

Configuration & Tuning

Indexer subsystem: feeder and spindexer control

Components

Feeder

Spindexer

IndexerSubsystem API

`runIndexer()` — fixed velocity

`runIndexer(DoubleSupplier flywheelRPS)` — flywheel-matched velocity

Launch integration

Controller binding

​Components

​Feeder

​Spindexer

​IndexerSubsystem API

​runIndexer() — fixed velocity

​runIndexer(DoubleSupplier flywheelRPS) — flywheel-matched velocity

​Launch integration

​Controller binding

Components

Feeder

Spindexer

IndexerSubsystem API

`runIndexer()` — fixed velocity

`runIndexer(DoubleSupplier flywheelRPS)` — flywheel-matched velocity

Launch integration

Controller binding