4. 想制作追踪特定id的apriltag码的小车，为什么程序进不了else，感觉循环嵌套有误？
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    • 想制作追踪特定id的apriltag码的小车，为什么程序进不了else，感觉循环嵌套有误？

    • H
       

      # Blob Detection Example
#
# This example shows off how to use the find_blobs function to find color
# blobs in the image. This example in particular looks for dark green objects.

import sensor, image, time, math
import car
from pid import PID

# You may need to tweak the above settings for tracking green things...
# Select an area in the Framebuffer to copy the color settings.

sensor.reset() # Initialize the camera sensor.
sensor.set_pixformat(sensor.RGB565) # use RGB565.
sensor.set_framesize(sensor.QQVGA) # use QQVGA for speed.
sensor.skip_frames(30) # Let new settings take affect.
sensor.set_auto_gain(False)
sensor.set_auto_whitebal(False) # turn this off.
clock = time.clock() # Tracks FPS.

# For color tracking to work really well you should ideally be in a very, very,
# very, controlled enviroment where the lighting is constant...
green_threshold   = (76, 96, -110, -30, 8, 66)
size_threshold = 2000
x_pid = PID(p=0.5, i=1, imax=100)
h_pid = PID(p=0.05, i=0.1, imax=50)


while(True):
    clock.tick() # Track elapsed milliseconds between snapshots().
    img = sensor.snapshot() # Take a picture and return the image.
    for tag in img.find_apriltags():
      if tag.id()==1:
           x_error = tag[6]-img.width()/2
           h_error = tag[2]*tag[3]-size_threshold
           print("x error: ", x_error)
           '''
           for b in blobs:
               # Draw a rect around the blob.
               img.draw_rectangle(b[0:4]) # rect
               img.draw_cross(b[5], b[6]) # cx, cy
           '''
           img.draw_rectangle(tag[0:4]) # rect
           img.draw_cross(tag[6], tag[7]) # cx, cy
           x_output=x_pid.get_pid(x_error,1)
           h_output=h_pid.get_pid(h_error,1)
           print("h_output",h_output)
           car.run(-h_output-x_output,-h_output+x_output)
      else: 
           car.run(18,-18)
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    • 你的这个else，对应的是for，而不是if。

      解决办法：else再加一个缩进，和if对齐。

      0