SimplePID.cs

[System.Serializable]
public class SimplePID {
    public float Kp = 1f;
    public float Ki = 0f;
    public float Kd = .1f;

    float _lastError;
    float _p, _i, _d;

    public void Reset() {
        _lastError = 0;
    }

    public float Update(float error, float dt) {
        _p = error;
        _i += error * dt;
        _d = (error - _lastError) / dt;
        _lastError = error;
        return _p * Kp + _i * Ki + _d * Kd;
    }
}