How to set an Elevator's target Height?

Create and Configure our Elevator

Our Arm will easily configure the SmartMotorController and create a simple and intuitive interface.

ExampleSubsystem.java

// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.

package frc.robot.subsystems;

import static edu.wpi.first.units.Units.Amps;
import static edu.wpi.first.units.Units.Meters;
import static edu.wpi.first.units.Units.MetersPerSecond;
import static edu.wpi.first.units.Units.MetersPerSecondPerSecond;
import static edu.wpi.first.units.Units.Feet;
import static edu.wpi.first.units.Units.Pounds;
import static edu.wpi.first.units.Units.Seconds;

import com.revrobotics.spark.SparkLowLevel.MotorType;
import com.revrobotics.spark.SparkMax;

import edu.wpi.first.math.controller.ArmFeedforward;
import edu.wpi.first.math.system.plant.DCMotor;
import edu.wpi.first.wpilibj2.command.Command;
import edu.wpi.first.wpilibj2.command.SubsystemBase;
import yams.mechanisms.SmartMechanism;
import yams.mechanisms.config.ElevatorConfig;
import yams.mechanisms.positional.Elevator;
import yams.motorcontrollers.SmartMotorController;
import yams.motorcontrollers.SmartMotorControllerConfig;
import yams.motorcontrollers.SmartMotorControllerConfig.ControlMode;
import yams.motorcontrollers.SmartMotorControllerConfig.MotorMode;
import yams.motorcontrollers.SmartMotorControllerConfig.TelemetryVerbosity;
import yams.motorcontrollers.local.SparkWrapper;
import yams.gearing.GearBox;
import yams.gearing.MechanismGearing;

public class ExampleSubsystem extends SubsystemBase {

  private SmartMotorControllerConfig smcConfig = new SmartMotorControllerConfig(this)
  .withControlMode(ControlMode.CLOSED_LOOP)
  // Mechanism Circumference is the distance traveled by each mechanism rotation converting rotations to meters.
  .withMechanismCircumference(Meters.of(Inches.of(0.25).in(Meters) * 22))
  // Feedback Constants (PID Constants)
  .withClosedLoopController(4, 0, 0, MetersPerSecond.of(0.5), MetersPerSecondPerSecond.of(0.5))
  .withSimClosedLoopController(4, 0, 0, MetersPerSecond.of(0.5), MetersPerSecondPerSecond.of(0.5))
  // Feedforward Constants
  .withFeedforward(new ElevatorFeedforward(0, 0, 0))
  .withSimFeedforward(new ElevatorFeedforward(0, 0, 0))
  // Telemetry name and verbosity level
  .withTelemetry("ElevatorMotor", TelemetryVerbosity.HIGH)
  // Gearing from the motor rotor to final shaft.
  // In this example gearbox(3,4) is the same as gearbox("3:1","4:1") which corresponds to the gearbox attached to your motor.
  .withGearing(new MechanismGearing(GearBox.fromReductionStages(3, 4)))
  // Motor properties to prevent over currenting.
  .withMotorInverted(false)
  .withIdleMode(MotorMode.BRAKE)
  .withStatorCurrentLimit(Amps.of(40))
  .withClosedLoopRampRate(Seconds.of(0.25))
  .withOpenLoopRampRate(Seconds.of(0.25));

  // Vendor motor controller object
  private SparkMax spark = new SparkMax(4, MotorType.kBrushless);

  // Create our SmartMotorController from our Spark and config with the NEO.
  private SmartMotorController sparkSmartMotorController = new SparkWrapper(spark, DCMotor.getNEO(1), smcConfig);

  private ElevatorConfig elevconfig = new ElevatorConfig(sparkSmartMotorController)
      .withStartingHeight(Meters.of(0.5))
      .withHardLimits(Meters.of(0), Meters.of(3))
      .withTelemetry("Elevator", TelemetryVerbosity.HIGH)
      .withMass(Pounds.of(16));

  // Elevator Mechanism
  private Elevator elevator = new Elevator(elevconfig);

  /** Creates a new ExampleSubsystem. */
  public ExampleSubsystem() {}

  /**
   * Example command factory method.
   *
   * @return a command
   */
  public Command exampleMethodCommand() {
    // Inline construction of command goes here.
    // Subsystem::RunOnce implicitly requires `this` subsystem.
    return runOnce(
        () -> {
          /* one-time action goes here */
        });
  }

  /**
   * An example method querying a boolean state of the subsystem (for example, a digital sensor).
   *
   * @return value of some boolean subsystem state, such as a digital sensor.
   */
  public boolean exampleCondition() {
    // Query some boolean state, such as a digital sensor.
    return false;
  }

  @Override
  public void periodic() {
    // This method will be called once per scheduler run
    elevator.updateTelemetry();
  }

  @Override
  public void simulationPeriodic() {
    // This method will be called once per scheduler run during simulation
    elevator.simIterate();
  }
}

Create Commands with our Elevator

We use the Elevator class as a interface to create commands!

ExampleSubsystem.java

// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.

package frc.robot.subsystems;

import static edu.wpi.first.units.Units.Amps;
import static edu.wpi.first.units.Units.Meters;
import static edu.wpi.first.units.Units.MetersPerSecond;
import static edu.wpi.first.units.Units.MetersPerSecondPerSecond;
import static edu.wpi.first.units.Units.Feet;
import static edu.wpi.first.units.Units.Pounds;
import static edu.wpi.first.units.Units.Second;
import static edu.wpi.first.units.Units.Seconds;
import static edu.wpi.first.units.Units.Volts;

import com.revrobotics.spark.SparkLowLevel.MotorType;
import com.revrobotics.spark.SparkMax;

import edu.wpi.first.math.controller.ElevatorFeedforward;
import edu.wpi.first.math.system.plant.DCMotor;
import edu.wpi.first.units.measure.Distance;
import edu.wpi.first.wpilibj2.command.Command;
import edu.wpi.first.wpilibj2.command.SubsystemBase;
import yams.mechanisms.SmartMechanism;
import yams.mechanisms.config.ElevatorConfig;
import yams.mechanisms.positional.Elevator;
import yams.motorcontrollers.SmartMotorController;
import yams.motorcontrollers.SmartMotorControllerConfig;
import yams.motorcontrollers.SmartMotorControllerConfig.ControlMode;
import yams.motorcontrollers.SmartMotorControllerConfig.MotorMode;
import yams.motorcontrollers.SmartMotorControllerConfig.TelemetryVerbosity;
import yams.motorcontrollers.local.SparkWrapper;
import yams.gearing.GearBox;
import yams.gearing.MechanismGearing;

public class ExampleSubsystem extends SubsystemBase {

  private SmartMotorControllerConfig smcConfig = new SmartMotorControllerConfig(this)
  .withControlMode(ControlMode.CLOSED_LOOP)
  // Mechanism Circumference is the distance traveled by each mechanism rotation converting rotations to meters.
  .withMechanismCircumference(Meters.of(Inches.of(0.25).in(Meters) * 22))
  // Feedback Constants (PID Constants)
  .withClosedLoopController(4, 0, 0, MetersPerSecond.of(0.5), MetersPerSecondPerSecond.of(0.5))
  .withSimClosedLoopController(4, 0, 0, MetersPerSecond.of(0.5), MetersPerSecondPerSecond.of(0.5))
  // Feedforward Constants
  .withFeedforward(new ElevatorFeedforward(0, 0, 0))
  .withSimFeedforward(new ElevatorFeedforward(0, 0, 0))
  // Telemetry name and verbosity level
  .withTelemetry("ElevatorMotor", TelemetryVerbosity.HIGH)
  // Gearing from the motor rotor to final shaft.
  // In this example gearbox(3,4) is the same as gearbox("3:1","4:1") which corresponds to the gearbox attached to your motor.
  .withGearing(new MechanismGearing(GearBox.fromReductionStages(3, 4)))
  // Motor properties to prevent over currenting.
  .withMotorInverted(false)
  .withIdleMode(MotorMode.BRAKE)
  .withStatorCurrentLimit(Amps.of(40))
  .withClosedLoopRampRate(Seconds.of(0.25))
  .withOpenLoopRampRate(Seconds.of(0.25));

  // Vendor motor controller object
  private SparkMax spark = new SparkMax(4, MotorType.kBrushless);

  // Create our SmartMotorController from our Spark and config with the NEO.
  private SmartMotorController sparkSmartMotorController = new SparkWrapper(spark, DCMotor.getNEO(1), smcConfig);

  private ElevatorConfig elevconfig = new ElevatorConfig(sparkSmartMotorController)
      .withStartingHeight(Meters.of(0.5))
      .withHardLimits(Meters.of(0), Meters.of(3))
      .withTelemetry("Elevator", TelemetryVerbosity.HIGH)
      .withMechanismPositionConfig(m_robotToMechanism)
      .withMass(Pounds.of(16));

  // Elevator Mechanism
  private Elevator elevator = new Elevator(elevconfig);

  /**
   * Set the height of the elevator.
   * @param angle Distance to go to.
   */
  public Command setHeight(Distance height) { return elevator.setHeight(height);}

  /**
   * Move the elevator up and down.
   * @param dutycycle [-1, 1] speed to set the elevator too.
   */
  public Command set(double dutycycle) { return elevator.set(dutycycle);}

  /** Creates a new ExampleSubsystem. */
  public ExampleSubsystem() {}

  @Override
  public void periodic() {
    // This method will be called once per scheduler run
    elevator.updateTelemetry();
  }

  @Override
  public void simulationPeriodic() {
    // This method will be called once per scheduler run during simulation
    elevator.simIterate();
  }
}

Bind buttons to our Elevator

We bind buttons to use the Commands from our Elevator

RobotContainer.java

// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.

package frc.robot;

import frc.robot.Constants.OperatorConstants;
import frc.robot.commands.Autos;
import frc.robot.commands.ExampleCommand;
import frc.robot.subsystems.ExampleSubsystem;

import static edu.wpi.first.units.Units.Meters;

import edu.wpi.first.wpilibj2.command.Command;
import edu.wpi.first.wpilibj2.command.button.CommandXboxController;
import edu.wpi.first.wpilibj2.command.button.Trigger;

/**
 * This class is where the bulk of the robot should be declared. Since Command-based is a
 * "declarative" paradigm, very little robot logic should actually be handled in the {@link Robot}
 * periodic methods (other than the scheduler calls). Instead, the structure of the robot (including
 * subsystems, commands, and trigger mappings) should be declared here.
 */
public class RobotContainer {
  // The robot's subsystems and commands are defined here...
  private final ExampleSubsystem m_exampleSubsystem = new ExampleSubsystem();

  // Replace with CommandPS4Controller or CommandJoystick if needed
  private final CommandXboxController m_driverController =
      new CommandXboxController(OperatorConstants.kDriverControllerPort);

  /** The container for the robot. Contains subsystems, OI devices, and commands. */
  public RobotContainer() {
    // Configure the trigger bindings
    configureBindings();

    // Set the default command to force the elevator to go to 0.
    m_exampleSubsystem.setDefaultCommand(m_exampleSubsystem.setHeight(Meters.of(0)));
  }

  /**
   * Use this method to define your trigger->command mappings. Triggers can be created via the
   * {@link Trigger#Trigger(java.util.function.BooleanSupplier)} constructor with an arbitrary
   * predicate, or via the named factories in {@link
   * edu.wpi.first.wpilibj2.command.button.CommandGenericHID}'s subclasses for {@link
   * CommandXboxController Xbox}/{@link edu.wpi.first.wpilibj2.command.button.CommandPS4Controller
   * PS4} controllers or {@link edu.wpi.first.wpilibj2.command.button.CommandJoystick Flight
   * joysticks}.
   */
  private void configureBindings() {
    
    // Schedule `setAngle` when the Xbox controller's B button is pressed,
    // cancelling on release.
    m_driverController.a().whileTrue(m_exampleSubsystem.setHeight(Meters.of(0.5)));
    m_driverController.b().whileTrue(m_exampleSubsystem.setHeight(Meters.of(1)));
    // Schedule `set` when the Xbox controller's B button is pressed,
    // cancelling on release.
    m_driverController.x().whileTrue(m_exampleSubsystem.set(0.3));
    m_driverController.y().whileTrue(m_exampleSubsystem.set(-0.3));

  }

  /**
   * Use this to pass the autonomous command to the main {@link Robot} class.
   *
   * @return the command to run in autonomous
   */
  public Command getAutonomousCommand() {
    // An example command will be run in autonomous
    return Autos.exampleAuto(m_exampleSubsystem);
  }
}

Simulate our Elevator!

We can use our Elevator in simulation, with the exact same code that will control the real robot!

Connect an Xbox controller to your system and drag and drop from System Joysticks to Joystick[0]

Open up the Simulated mechanism with NetworkTables -> SmartDashboard -> Arm -> mechanism

Resize Elevator/mechanism to your liking

Press Teleoperated in Robot State then you can use your controller like its controlling the real robot!

Congratulations on successfully programming your Elevator!! 🎉🎉