How to Move Servo Motor Sg90

Question

Like I would do where the print("RED"), print("GREEN") and print("BLUE") to move a servo motor at 180°, what happens is that the engine does not move, (I’m using Raspberry pi 3 b+).

if r >= 50 and g >= 50 and b >= 50:
        print("WHITE")
    elif r > g and r > b:
        print("RED")
        try:
            p.ChangeDutyCycle(7.5)
            time.sleep(1)
            p.ChangeDutyCycle(12.5)
            time.sleep(1)
            p.ChangeDutyCycle(2.5)
            time.sleep(1)
    elif g > r and g > b:
        print("GREEN")
        try:
            p.ChangeDutyCycle(7.5)
            time.sleep(1)
            p.ChangeDutyCycle(12.5)
            time.sleep(1)
            p.ChangeDutyCycle(2.5)
            time.sleep(1)
    else:
        print("BLUE")
        try:
            p.ChangeDutyCycle(7.5)
            time.sleep(1)
            p.ChangeDutyCycle(12.5)
            time.sleep(1)
            p.ChangeDutyCycle(2.5)
            time.sleep(1)
    return rect

---

import cv2
import numpy as np
import matplotlib.pyplot as plt
import RPi.GPIO as GPIO
import time
from matplotlib.animation import FuncAnimation

GPIO.setmode(GPIO.BOARD)
GPIO.setup(7,GPIO.OUT)

p = GPIO.PWM(7,50)
p.start(7.5)

def grab_frame(cap):
    ret,frame = cap.read()
    return cv2.cvtColor(frame,cv2.COLOR_BGR2RGB)

def atualizar(i):
    img = grab_frame(captura)
    im1.set_data(img)
    im2.set_data(retangulo(img))

def close(event):
    if event.key == 'q':
        plt.close(event.canvas.figure)

def unique_count_app(a):
    colors, count = np.unique(a.reshape(-1,a.shape[-1]), axis=0, return_counts=True)
    return colors[count.argmax()]

def retangulo(img):
    r, g, b = contar_kmeans(img)
    h, w, c = img.shape
    rect = np.zeros((h, w, 3), np.uint8)
    rect[0:h, 0:w] = (r,g,b)
    if r >= 50 and g >= 50 and b >= 50:
        print("WHITE")
    elif r > g and r > b:
        print("RED")
        try:
            p.ChangeDutyCycle(7.5)
            time.sleep(1)
            p.ChangeDutyCycle(12.5)
            time.sleep(1)
            p.ChangeDutyCycle(2.5)
            time.sleep(1)
    elif g > r and g > b:
        print("GREEN")
        try:
            p.ChangeDutyCycle(7.5)
            time.sleep(1)
            p.ChangeDutyCycle(12.5)
            time.sleep(1)
            p.ChangeDutyCycle(2.5)
            time.sleep(1)
    else:
        print("BLUE")
        try:
            p.ChangeDutyCycle(7.5)
            time.sleep(1)
            p.ChangeDutyCycle(12.5)
            time.sleep(1)
            p.ChangeDutyCycle(2.5)
            time.sleep(1)
    return rect

def contar_kmeans(img):
    data = np.reshape(img, (-1,3))
    data = np.float32(data)
    criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 10, 1.0)
    flags = cv2.KMEANS_RANDOM_CENTERS
    compactness, labels, centers = cv2.kmeans(data, 1, None, criteria, 10, flags)
    return centers[0]

captura = cv2.VideoCapture(0)
imagem = grab_frame(captura)

#Cria os dois subplots
ax1 = plt.subplot(1,2,1)
    ax2 = plt.subplot(1,2,2)

    #Cria duas imagens nos subplots
    im1 = ax1.imshow(imagem)
    im2 = ax2.imshow(retangulo(imagem))

    #Animação e atualização
    ani = FuncAnimation(plt.gcf(), atualizar, interval=200)

    except KeyboardInterrupt:
    p.stop()

    GPIO.cleanup()
    #Fechar 
    cid = plt.gcf().canvas.mpl_connect("key_press_event", close)
    #Mostrar o gráfico
    plt.show()