问如何在开放式简历中识别头部运动？

EN

   import cv2
import numpy as np
"""
Created on Mon Mar 2 11:38:49 2020

@author: bradl
"""
# Open Camera
camera = cv2.VideoCapture(0)
camera.set(10, 200)

face_cascade = cv2.CascadeClassifier('haarcascades/face.xml')
##smile = cv2.CascadeClassifier('haarcascades/smile.xml')
eye_cascade = cv2.CascadeClassifier('haarcascades/eye.xml')

while True:
    ret, img = camera.read()
    ## converts to gray
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    ## determines what a face is and how it is found
    faces = face_cascade.detectMultiScale(gray, 1.3, 5)
    for (x,y,w,h) in faces:
        ## Determines the starting and ending co-ordinates for a blue rectangle to be drawn around the face
        cv2.rectangle (img, (x,y), (x+w, y+h), (255,0,0), 2)
        ## Declares the region of the image where the eyes will be 
        roi_gray = gray[y:y+h, x:x+w]
        roi_color = img[y:y+h, x:x+w]
        ## Determines what an eye is based on the eye haar cascade xml file
        eyes = eye_cascade.detectMultiScale(roi_gray)
        for (ex,ey,ew,eh) in eyes: 
            ##Draws green rectangles around the co-ordintates for eyes 
            cv2.rectangle(roi_color, (ex, ey),(ex+ew,ey+eh), (0,255,0),2)

    ##Displays camera        
    cv2.imshow('Image',img)
    ##Requires the user to press escape to exit the program
    k = cv2.waitKey(40) 
    if k == 27: 
            break