Package frc.robot.shared.subsystems

Class AbstractVelocitySubsystem<TConfig extends AbstractVelocitySubsystemConfig>

java.lang.Object

edu.wpi.first.wpilibj2.command.SubsystemBase

frc.robot.shared.subsystems.AbstractSubsystem<TConfig>

frc.robot.shared.subsystems.AbstractMotorSubsystem<TConfig>

frc.robot.shared.subsystems.AbstractVelocitySubsystem<TConfig>

Type Parameters:

TConfig - configuration type supplying velocity limits, PID gains, and feedforward gains

All Implemented Interfaces:

edu.wpi.first.util.sendable.Sendable, edu.wpi.first.wpilibj2.command.Subsystem

Direct Known Subclasses:

FeederSubsystem, IndexerSubsystem, IntakeSubsystem, ShooterSubsystem

public abstract class AbstractVelocitySubsystem<TConfig extends AbstractVelocitySubsystemConfig>
extends AbstractMotorSubsystem<TConfig>

Base subsystem for mechanisms that maintain a target velocity using feedforward and PID control.

All RPM values in the public API represent mechanism (flywheel) speed after gear reduction, not motor shaft speed. The gear ratio is applied at the motor encoder conversion layer, so subsystem code never deals with motor-side rotations. Internally, all velocity math uses radians per second to align with WPILib conventions.

When maximumAccelerationRpmPerSecond in config is greater than zero, the subsystem uses a trapezoidal profile to ramp velocity smoothly. When it is zero, the subsystem applies direct PID + feedforward control without a ramp.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static interface	AbstractVelocitySubsystem.TriFunction<A,B,C,R>	Functional interface for a three-argument function used by buildVelocityMotor(frc.robot.shared.config.AbstractVelocitySubsystemConfig, TMotorConfig, java.util.function.Function<TMotorConfig, frc.robot.devices.motor.Motor>, frc.robot.shared.subsystems.AbstractVelocitySubsystem.TriFunction<TMotorConfig, java.util.function.Supplier<java.lang.Double>, java.util.function.Supplier<java.lang.Double>, frc.robot.devices.motor.Motor>).

Field Summary

Fields

Modifier and Type	Field	Description
protected final edu.wpi.first.math.controller.PIDController	controller	PID controller that corrects velocity error.

Fields inherited from class frc.robot.shared.subsystems.AbstractMotorSubsystem

feedforward, motor, motorInputs

Fields inherited from class frc.robot.shared.subsystems.AbstractSubsystem

className, config, enabled, kDt, log, verbose

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractVelocitySubsystem(TConfig config, Motor motor)	Creates a velocity-controlled subsystem with PID, feedforward, and optional trapezoidal velocity ramp.

Method Summary

Modifier and Type	Method	Description
protected static <TMotorConfig extends MotorConfig> Motor	buildVelocityMotor(AbstractVelocitySubsystemConfig config, TMotorConfig motorConfig, Function<TMotorConfig,Motor> realFactory, AbstractVelocitySubsystem.TriFunction<TMotorConfig,Supplier<Double>,Supplier<Double>,Motor> simFactory)	Builds the correct motor implementation for the current environment using the shared velocity subsystem pattern.
double	getIdleVelocityRpm()	Returns the configured idle velocity in RPM.
double	getMeasuredVelocityRpm()	Returns the current measured velocity in RPM.
double	getTargetVelocityRpm()	Returns the current target velocity in RPM.
boolean	isAtTargetVelocity()	Reports whether the measured velocity is within tolerance of the target and has been stable for the configured settle time.
boolean	isReady()	Reports whether the subsystem is ready for downstream consumers.
boolean	isWithinTolerance()	Reports whether the measured velocity is currently within tolerance of the target, without requiring the settle timer.
void	periodic()	Refreshes motor, feedforward, and PID configuration when not attached to the FMS, and logs common velocity telemetry.
void	seekVelocity()	Advances the velocity controller by one cycle: updates motor inputs, steps the optional velocity ramp, computes PID + feedforward, and applies the voltage to the motor.
void	setTargetVelocityRpm(double targetRpm)	Sets a new target velocity for the mechanism.
void	stop()	Resets velocity controller state to zero and stops the motor.

Methods inherited from class frc.robot.shared.subsystems.AbstractMotorSubsystem

applyVoltage, getMeasuredPositionRadians, getMeasuredVelocityRadiansPerSecond, getSysIdRoutine, logSysIdEnd, logSysIdInterrupted, logSysIdStart, refreshFeedforward, updateAndLogMotorInputs

Methods inherited from class frc.robot.shared.subsystems.AbstractSubsystem

getConfig, isFMSAttached, isSimulation, isSubsystemDisabled, isVerbose, isVerboseLoggingEnabled, logDisabled, reportWarning

Methods inherited from class edu.wpi.first.wpilibj2.command.SubsystemBase

addChild, getName, getSubsystem, initSendable, setName, setSubsystem

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface edu.wpi.first.wpilibj2.command.Subsystem

defer, getCurrentCommand, getDefaultCommand, idle, register, removeDefaultCommand, run, runEnd, runOnce, setDefaultCommand, simulationPeriodic, startEnd, startRun

Field Details

controller

protected final edu.wpi.first.math.controller.PIDController controller

PID controller that corrects velocity error.

Constructor Details

AbstractVelocitySubsystem

protected AbstractVelocitySubsystem(TConfig config,
 Motor motor)

Creates a velocity-controlled subsystem with PID, feedforward, and optional trapezoidal velocity ramp.

Parameters:

config - configuration bundle supplying velocity limits, PID gains, and feedforward gains

motor - motor controller that reports velocity and accepts voltage commands, or null to use a disabled no-op motor

Method Details

buildVelocityMotor

protected static <TMotorConfig extends MotorConfig>
Motor buildVelocityMotor(AbstractVelocitySubsystemConfig config,
 TMotorConfig motorConfig,
 Function<TMotorConfig,Motor> realFactory,
 AbstractVelocitySubsystem.TriFunction<TMotorConfig,Supplier<Double>,Supplier<Double>,Motor> simFactory)

Builds the correct motor implementation for the current environment using the shared velocity subsystem pattern.

Returns null when the config is disabled so the parent falls back to DisabledMotor. Real and simulation motors are selected using the provided factory functions.

Type Parameters:

TMotorConfig - concrete motor config type

Parameters:

config - velocity subsystem config supplying max velocity and acceleration for sim motor suppliers

motorConfig - motor-specific configuration bundle (CAN ID, gear ratio, inversion, etc.)

realFactory - factory function that creates the real motor from a motor config

simFactory - factory function that creates the sim motor from a motor config and velocity/acceleration suppliers

Returns:

configured motor, or null when the subsystem is disabled

periodic

public void periodic()

Refreshes motor, feedforward, and PID configuration when not attached to the FMS, and logs common velocity telemetry.

Override this if you need additional periodic behavior, but call super.periodic() to keep live tuning updates and common telemetry active.

Specified by:

periodic in interface edu.wpi.first.wpilibj2.command.Subsystem

Overrides:

periodic in class AbstractMotorSubsystem<TConfig extends AbstractVelocitySubsystemConfig>

setTargetVelocityRpm

public void setTargetVelocityRpm(double targetRpm)

Sets a new target velocity for the mechanism. Values are clamped to the configured maximum in both directions.

The target is in mechanism RPM (after gear reduction). Positive values spin the mechanism forward; negative values spin it in reverse. Requested and clamped values are logged for tuning visibility.

The settle timer and tolerance flag are only reset when the measured velocity is outside tolerance of the new target. This prevents reset-flicker in distance-based commands where the interpolated target drifts slightly each cycle while the mechanism is already tracking within tolerance. Large target jumps (e.g., idle to full speed) still trigger a full reset and settle window.

Parameters:

targetRpm - desired mechanism velocity in RPM (0 to stop, positive for forward, negative for reverse)

seekVelocity

public void seekVelocity()

Advances the velocity controller by one cycle: updates motor inputs, steps the optional velocity ramp, computes PID + feedforward, and applies the voltage to the motor.

isAtTargetVelocity

public boolean isAtTargetVelocity()

Reports whether the measured velocity is within tolerance of the target and has been stable for the configured settle time.

Returns:

true when the mechanism is at the target velocity and has been stable long enough

isWithinTolerance

public boolean isWithinTolerance()

Reports whether the measured velocity is currently within tolerance of the target, without requiring the settle timer.

Use this for continuously-updating targets (such as distance-based RPM) where the settle timer resets each time the target changes. isAtTargetVelocity() is still preferred for fixed-target scenarios where stability over time matters.

Returns:

true when the measured velocity is within tolerance of the current target right now

isReady

public boolean isReady()

Reports whether the subsystem is ready for downstream consumers.

This is a stable, uniform API that all velocity subsystems expose. Composite commands and cross-subsystem suppliers should prefer this method over subsystem-specific readiness checks so wiring code stays consistent across mechanisms.

Returns:

true when the mechanism is at the target velocity and has been stable long enough

getTargetVelocityRpm

public double getTargetVelocityRpm()

Returns the current target velocity in RPM.

Returns:

target velocity in mechanism RPM

getMeasuredVelocityRpm

public double getMeasuredVelocityRpm()

Returns the current measured velocity in RPM.

Returns:

measured velocity in mechanism RPM

getIdleVelocityRpm

public double getIdleVelocityRpm()

Returns the configured idle velocity in RPM.

Commands can use this to set the target to the idle speed without direct config access.

Returns:

idle velocity in mechanism RPM from config

stop

public void stop()

Resets velocity controller state to zero and stops the motor.

Clears the target velocity, setpoint, tolerance flag, and trapezoidal profile state so the mechanism is fully idle.

Overrides:

stop in class AbstractMotorSubsystem<TConfig extends AbstractVelocitySubsystemConfig>