Limelight always returning default value of 0.0

[brandonmcd]

Hey everyone,

I’m running into an issue setting up a Limelight vision system where it’s always returning the default value, and I’m not sure what’s causing it. I’ve attached some screenshots to give you a clearer picture of what’s going on.

The goal is to align the bot with an apriltag when the 9 button is held down. Here is the code.

package frc.robot.commands.LimeLightVision;

import edu.wpi.first.networktables.NetworkTable;
import edu.wpi.first.networktables.NetworkTableEntry;
import edu.wpi.first.networktables.NetworkTableInstance;
import edu.wpi.first.wpilibj2.command.Command;
import frc.robot.subsystems.CANDrivetrain;

public class AlignWithTag extends Command {

    private final CANDrivetrain drivetrain;
    private final NetworkTable table;
    private static final double Kp = -0.1;
    private static final double min_command = 0.05;

    // Constructor
    public AlignWithTag(CANDrivetrain drivetrain) {
        this.drivetrain = drivetrain;
        table = NetworkTableInstance.getDefault().getTable("limelight");
        addRequirements(drivetrain);
    }


    // Called when the command is initially scheduled.
    @Override
    public void initialize() {
        // Initialization code, if any
    }

    // Called every time the scheduler runs while the command is scheduled.
    @Override
    public void execute() {
           NetworkTableEntry tx = table.getEntry("tx"); 
            double x = tx.getDouble(0.0);
            double heading_error = -x;
            System.out.println("Executing with error " + heading_error);
            double steering_adjust = 0.0;
            if (Math.abs(heading_error) > 1.0) {
                steering_adjust = Kp * heading_error + (heading_error > 0 ? -min_command : min_command);
            }
            drivetrain.arcadeDrive(0, steering_adjust);
        
    }

    // Called once the command ends or is interrupted.
    @Override
    public void end(boolean interrupted) {
        drivetrain.arcadeDrive(0, 0); //Stop the drivetrain when the command ends
    }

    // Returns true when the command should end.
    @Override
    public boolean isFinished() {
        return false; // Modify this as needed based on your command's ending condition
    }
}

package frc.robot;

import java.lang.reflect.Method;
import java.util.Arrays;

import edu.wpi.first.wpilibj.Joystick;
import edu.wpi.first.wpilibj.smartdashboard.SendableChooser;
import edu.wpi.first.wpilibj.smartdashboard.SmartDashboard;
import edu.wpi.first.wpilibj2.command.Command;
import edu.wpi.first.wpilibj2.command.InstantCommand;
import edu.wpi.first.wpilibj2.command.RunCommand;
import edu.wpi.first.wpilibj2.command.button.JoystickButton;
import frc.robot.commands.Autos;
import frc.robot.commands.LimeLightVision.AlignWithTag;
import frc.robot.subsystems.CANDrivetrain;
//import frc.robot.subsystems.CANLauncher;

public class RobotContainer {
  private final CANDrivetrain m_drivetrain = new CANDrivetrain();
  private final SendableChooser<Command> autoChooser = new SendableChooser<>();
  private final AlignWithTag m_align = new AlignWithTag(m_drivetrain);
  //private final CANLauncher m_launcher = new CANLauncher();

  // Assuming these port numbers are correct for your setup.
  private final Joystick m_driver = new Joystick(Constants.OperatorConstants.kDriverControllerPort);
  //private final Joystick m_operator = new Joystick(Constants.OperatorConstants.kOperatorControllerPort);

  public RobotContainer() {
    configureBindings();
    populateAutoCommands();
  }
  
private void configureBindings() {
    m_drivetrain.setDefaultCommand(
        new RunCommand(
            () -> m_drivetrain.arcadeDrive(
                    -m_driver.getY() * Constants.OperatorConstants.kDriverSpeedMultiplier, 
                    -m_driver.getX() * Constants.OperatorConstants.kDriverSpeedMultiplier),
            m_drivetrain));

    // Create a JoystickButton object for the button
    JoystickButton alignButton = new JoystickButton(m_driver, 9);

   // Bind align command to the button
    alignButton.onTrue(m_align);
}
            

   

    // Commented out the following as we do not have a launcher yet.
    /*
    m_operatorController
        .a()
        .whileTrue(
            new PrepareLaunch(m_launcher)
                .withTimeout(LauncherConstants.kLauncherDelay)
                .andThen(new LaunchNote(m_launcher))
                .handleInterrupt(() -> m_launcher.stop()));

    m_operatorController.leftBumper().whileTrue(m_launcher.getIntakeCommand());
    */
  
 private void populateAutoCommands() {
        Method[] methods = Autos.class.getDeclaredMethods();
        Arrays.stream(methods)
              .filter(method -> Command.class.isAssignableFrom(method.getReturnType()) && method.getParameterCount() == 1)
              .forEach(method -> {
                  try {
                      Command command = (Command) method.invoke(null, m_drivetrain);
                      autoChooser.addOption(method.getName(), command);
                  } catch (Exception e) {
                      e.printStackTrace();
                  }
              });
        SmartDashboard.putData("Auto Mode", autoChooser);
    }

    public Command getAutonomousCommand() {
        return autoChooser.getSelected();
    }

    public String getSelectedAutoName() {
      return autoChooser.getSelected().getName();
  }

}