import sensor, image, time
from pid import PID
from pyb import Servo
pan_servo=Servo(1)
tilt_servo=Servo(2)
red_threshold = (13, 49, 18, 61, 6, 47)
pan_pid = PID(p=0.07, i=0, imax=90) #脱机运行或者禁用图像传输，使用这个PID
tilt_pid = PID(p=0.05, i=0, imax=90) #脱机运行或者禁用图像传输，使用这个PID
#pan_pid = PID(p=0.1, i=0, imax=90)#在线调试使用这个PID
#tilt_pid = PID(p=0.1, i=0, imax=90)#在线调试使用这个PID
sensor.reset()
# Sensor settings
sensor.set_contrast(1)
sensor.set_gainceiling(16)
# HQVGA and GRAYSCALE are the best for face tracking.
sensor.set_framesize(sensor.HQVGA)
sensor.set_pixformat(sensor.GRAYSCALE)
clock = time.clock() # Tracks FPS.
face_cascade = image.HaarCascade("frontalface", stages=25)
def find_max(blobs):
max_size=0
for blob in blobs:
if blob[2]*blob[3] > max_size:
max_blob=blob
max_size = blob[2]*blob[3]
return max_blob
while(True):
clock.tick() # Track elapsed milliseconds between snapshots().
img = sensor.snapshot() # Take a picture and return the image.
objects = img.find_features(face_cascade, threshold=0.75, scale=1.35)
if objects:
max_blob = find_max(objects)
pan_error = max_blob.cx()-img.width()/2
tilt_error = max_blob.xy()-img.height()/2
print("pan_error: ", pan_error)
img.draw_rectangle(max_blob.rect()) # rect
pan_output=pan_pid.get_pid(pan_error,1)/2
tilt_output=tilt_pid.get_pid(tilt_error,1)
print("pan_output",pan_output)
pan_servo.angle(pan_servo.angle()+pan_output)
tilt_servo.angle(tilt_servo.angle()-tilt_output)
```
