Limelight and April Tag Auto Align Help

Technical Programming
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1

Hello, my team has been having trouble getting the April Tag auto alignment to work. We got our code from the Limelight docs. The issue is that when we press a button, the swerves angle themselves to the April Tag, but they don’t move forward and the robot doesn’t rotate. However, we are looking for the ability to press a button to have the swerves rotate the robot towards the April Tag and have the driver manually drive up to it. We are using Limelight software. Here is our code; the auto-alignment function is in RobotContainer.java. Is there something we are doing incorrectly? Thank you for the help!

2

We are still trying to fix this issue, any help would be greatly appreciated!

3

What do you overwrite your xSpeed with forward_limelight if you want the driver to keep full control on location?

4

I would suggest using SwerveRequest.FieldCentricFacingAngle, that was what I switched to a couple weeks ago and it works great.

5

That was just a test to see if we could do the auto-align without the driver strafing, but that didn’t work either. Is it as simple as using a drive function with a translation2d for the Xbox controller inputs and the limelight’s tx value for the rotation? Here is what I did if that makes sense

 public void execute() {
       // if(NetworkTableInstance.getDefault().getTable("limelight").getEntry("tv").getBoolean() == NetworkTableInstance.getDefault().getTable("limelight").getEntry("tx").setInteger(7))
        if(LimelightHelpers.getLatestResults("limelight") != null) { 

            //desiredStrafe = NetworkTableInstance.getDefault().getTable("limelight").getEntry("ty").getDouble(0);

            heading = -NetworkTableInstance.getDefault().getTable("limelight").getEntry("tx").getDouble(0);
            //Do we divide by something here?
        }else{
            heading = 0;
            System.out.println("Failed to see target");
        }

          drive.drive(new Translation2d(Math.pow(translationX.getAsDouble(), 3) * Constants.SwerveConstants.maxSwerveSpeedMS,
    Math.pow(translationY.getAsDouble(), 3) * Constants.SwerveConstants.maxSwerveSpeedMS),
    heading * Constants.SwerveConstants.maxSwerveSpeedMS,
false);
6

Look at that file: FRC2495-2024/src/main/java/frc/robot/commands/drivetrain/DrivetrainDriveUsingAprilTagCamera.java at main · FRC2495/FRC2495-2024 (github.com)

Tweak it for the Limelight, and you should be good to go.

7

Since the amp is 90 degrees perpendicular to where the gyro says field-oriented forward is at the start of the match, are you saying that we could auto-align by telling the robot to turn 90 degrees from the field-oriented forward direction? That would be a smart way of auto-aligning without vision

8

Will do, thanks! Do you know why the angle is divided by 90 here?

drivetrain.drive(
			-MathUtil.applyDeadband(joystick.getY(), JOYSTICK_AXIS_THRESHOLD),
			-MathUtil.applyDeadband(joystick.getX(), JOYSTICK_AXIS_THRESHOLD),
			-angle/90.00,
			true, true);
9

To normalize. Adjust as you want.

10

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