Falcon 500 ConfigAllowableClosedLoopError issue

[merelephant]

Hi! We’re running onboard motion magic control on our swerve motors. I’m using the onboard units and have configured the allowable closed loop error to be 1 degree or 72 sensor units (confirmed via Phoenix Tuner). However, the motors still twitch even when within that tolerance. Changing the tolerance to make it bigger doesn’t change the twitching, but it does make the motors stop within a greater tolerance (ie the twitching happens near setpoint ±error – within the error band). I’m not sure if I’m misunderstanding what ConfigAllowableClosedLoopError does – how can I make them not twitch within the tolerance?
The code is here: https://github.com/team2485/frc-2022/blob/develop/src/main/java/frc/robot/subsystems/drive/SwerveModule.java
Here’s all the motor configs:

turningMotorConfig.voltageCompSaturation = Constants.kNominalVoltage;
    turningMotorConfig.supplyCurrLimit.currentLimit = kTurningCurrentLimitAmps;
    turningMotorConfig.supplyCurrLimit.enable = true;
    turningMotorConfig.slot0.kP = kPTurning;
    turningMotorConfig.slot0.kD = kDTurning;
    turningMotorConfig.slot0.kF = kFTurning;
    turningMotorConfig.motionCruiseVelocity = kModuleMaxSpeedTurningPulsesPer100Ms;
    turningMotorConfig.motionAcceleration = kModuleMaxAccelerationTurningPulsesPer100MsSquared;
    this.m_turningMotor = new WL_TalonFX(turningMotorID);
    m_turningMotor.configAllSettings(turningMotorConfig);
    m_turningMotor.enableVoltageCompensation(true);
    m_turningMotor.configSelectedFeedbackSensor(
        TalonFXFeedbackDevice.IntegratedSensor, 0, Constants.kCANTimeoutMs);
    m_turningMotor.configIntegratedSensorAbsoluteRange(
        AbsoluteSensorRange.Signed_PlusMinus180, Constants.kCANTimeoutMs);
    m_turningMotor.setNeutralMode(NeutralMode.Brake);
    m_turningMotor.configAllowableClosedloopError(
        0, Units.degreesToRadians(1) / kTurningRadiansPerPulse, Constants.kCANTimeoutMs);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_1_General, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_2_Feedback0, 20);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_4_AinTempVbat, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_6_Misc, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_7_CommStatus, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_8_PulseWidth, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_9_MotProfBuffer, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_10_MotionMagic, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_10_Targets, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_11_UartGadgeteer, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_12_Feedback1, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_13_Base_PIDF0, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_14_Turn_PIDF1, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_15_FirmwareApiStatus, 255);
    m_turningMotor.setStatusFramePeriod(StatusFrameEnhanced.Status_Brushless_Current, 255);

[Joe_Ross]

When it’s twitching what does phoenix tuner self test say about it’s mode and inputs and outputs?

[bruingineer]

It sounds like the wheels on the border of allowable error.

Have you tried manually turning the wheels to the setpoint?

I.E. if the allowable error is 10 degrees (yes this is large for the sake of the example), and the wheel is manually placed at the goal angle, does the twitching still happen?

[merelephant]

@Joe_Ross @bruingineer thanks for the responses, I’ll test in phoenix tuner and test with a large allowable error at the center when I’m back in the shop tomorrow. One potential explanation might be that while graphing it in Glass it doesn’t go beyond the threshold, I’m only updating that every 10 ms over the CAN bus, and the loop is running at 1 ms. But I’ll update when I test further. Thanks!