THIS IS THE FULL CODE FOR THE STABILIZER.

// Librerias I2C para controlar el mpu6050
// la libreria MPU6050.h necesita I2Cdev.h, I2Cdev.h necesita Wire.h
#include "I2Cdev.h"
#include "MPU6050.h"
#include "Wire.h"

#include <Servo.h>
Servo servoX;  // create servo object to control a servo
// twelve servo objects can be created on most boards
Servo servoY;  // create servo object to control a servo
// twelve servo objects can be created on most boards
Servo servoZ;  // create servo object to control a servo

// La dirección del MPU6050 puede ser 0x68 o 0x69, dependiendo
// del estado de AD0. Si no se especifica, 0x68 estará implicito
MPU6050 sensor;

// Valores RAW (sin procesar) del acelerometro y giroscopio en los ejes x,y,z
int ax, ay, az;
int gx, gy, gz;
float ang_x = 0;  // variable to store the servo position
float ang_y = 0;  // variable to store the servo position

long tiempo_prev;
float dt;
float ang_x_prev, ang_y_prev;

const int buttonPin1 = 2;     // the number of the pushbutton pin
const int buttonPin2 = 3;     // the number of the pushbutton pin
int ang_1 = 5;
int ang_2 = 175;
int e = 90;
// variables will change:
int buttonState1 = 0;         // variable for reading the pushbutton status
int buttonState2 = 0;

void setup() {

  servoZ.attach(11);  // attaches the servo on pin 9 to the servo object
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin1, INPUT);
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin2, INPUT);

  Serial.begin(9600);    //Iniciando puerto serial
  Wire.begin();           //Iniciando I2C
  sensor.initialize();    //Iniciando el sensor

  if (sensor.testConnection()) Serial.println("Sensor iniciado correctamente");
  else Serial.println("Error al iniciar el sensor");

  servoX.attach(9);  // attaches the servo on pin 9 to the servo object
  servoY.attach(10);  // attaches the servo on pin 9 to the servo object

}

void loop() {
  // Leer las aceleraciones y velocidades angulares
  sensor.getAcceleration(&ax, &ay, &az);
  sensor.getRotation(&gx, &gy, &gz);

  dt = (millis() - tiempo_prev) / 1000.0;
  tiempo_prev = millis();

  //Calcular los ángulos con acelerometro
  float accel_ang_x = atan(ay / sqrt(pow(ax, 2) + pow(az, 2))) * (180.0 / 3.14);
  float accel_ang_y = atan(-ax / sqrt(pow(ay, 2) + pow(az, 2))) * (180.0 / 3.14);

  //Calcular angulo de rotación con giroscopio y filtro complemento
  ang_x = 0.98 * (ang_x_prev + (gx / 131) * dt) + 0.02 * accel_ang_x;
  ang_y = 0.98 * (ang_y_prev + (gy / 131) * dt) + 0.02 * accel_ang_y;



  //Mostrar los angulos separadas por un [tab]

  Serial.print("Rotacion en X: ");
  Serial.print(ang_x);
  Serial.print("Rotacion en Y: ");
  Serial.println(ang_y);


  servoX.write(ang_x);              // tell servo to go to position in variable 'pos'
  servoY.write(ang_y);              // tell servo to go to position in variable 'pos'
  delay(1);                       // waits 15ms for the servo to reach the position
  ang_x_prev = ang_x;
  ang_y_prev = ang_y;

  // read the state of the pushbutton value:
  buttonState1 = digitalRead(buttonPin1);
  buttonState2 = digitalRead(buttonPin2);

  // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
  if (buttonState1 == LOW && e >= ang_1) {
    e = e - 5;
    if (e >= ang_1) {
      servoZ.write(e);              // tell servo to go to position in variable 'pos'
      delay(20);
    }
    // waits 20ms for the servo to reach the position
  } else if (buttonState2 == LOW && e <= ang_2) {
    e = e + 5;
    if (e <= ang_2) {
      servoZ.write(e);              // tell servo to go to position in variable 'pos'
      delay(20);
    }
    // waits 20ms for the servo to reach the position
  }
}