Whip's PID Class

//Whip's PID controller class v6 - 11/22/17
public class PID
{
    double _kP = 0;
    double _kI = 0;
    double _kD = 0;
    double _integralDecayRatio = 0;
    double _lowerBound = 0;
    double _upperBound = 0;
    double _timeStep = 0;
    double _inverseTimeStep = 0;
    double _errorSum = 0;
    double _lastError = 0;
    bool _firstRun = true;
    bool _integralDecay = false;
    public double Value { get; private set; }

    public PID(double kP, double kI, double kD, double lowerBound, double upperBound, double timeStep)
    {
        _kP = kP;
        _kI = kI;
        _kD = kD;
        _lowerBound = lowerBound;
        _upperBound = upperBound;
        _timeStep = timeStep;
        _inverseTimeStep = 1 / _timeStep;
        _integralDecay = false;
    }

    public PID(double kP, double kI, double kD, double integralDecayRatio, double timeStep)
    {
        _kP = kP;
        _kI = kI;
        _kD = kD;
        _timeStep = timeStep;
        _inverseTimeStep = 1 / _timeStep;
        _integralDecayRatio = integralDecayRatio;
        _integralDecay = true;
    }

    public double Control(double error)
    {
        //Compute derivative term
        var errorDerivative = (error - _lastError) * _inverseTimeStep;

        if (_firstRun)
        {
            errorDerivative = 0;
            _firstRun = false;
        }

        //Compute integral term
        if (!_integralDecay)
        {
            _errorSum += error * _timeStep;

            //Clamp integral term
            if (_errorSum > _upperBound)
                _errorSum = _upperBound;
            else if (_errorSum < _lowerBound)
                _errorSum = _lowerBound;
        }
        else
        {
            _errorSum = _errorSum * (1.0 - _integralDecayRatio) + error * _timeStep;
        }

        //Store this error as last error
        _lastError = error;

        //Construct output
        this.Value = _kP * error + _kI * _errorSum + _kD * errorDerivative;
        return this.Value;
    }

    public double Control(double error, double timeStep)
    {
        _timeStep = timeStep;
        _inverseTimeStep = 1 / _timeStep;
        return Control(error);
    }

    public void Reset()
    {
        _errorSum = 0;
        _lastError = 0;
        _firstRun = true;
    }
}