openmv小车追小球

希望在电赛的时候，我可以帮到我们队，起到很重要的作用

mian.py

# 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, time
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() # 重置感光元件
sensor.set_pixformat(sensor.RGB565) # 设置彩图
sensor.set_framesize(sensor.QQVGA) # 设置图像的分辨率
sensor.skip_frames(10) # Let new settings take affect.
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...
red_threshold   = (0, 100, 12, 127, -102, 127)
size_threshold = 2000#标志参数
#摄像头检测到的小球的色块的面积，像素点数>2000,说明小车距离小球非常近
#设置小车后退一点，保持一段距离

#如果<2000,设置openmv去追踪小球
x_pid = PID(p=0.5, i=1, imax=100)#控制电机的方向
h_pid = PID(p=0.001, i=0.1, imax=50)#控制小车运动的速度
#如果速度太快了，可以把h_pid的p参数调小一点
#如果发现小车在拐角追球的时候，拐的角度非常大，x_pid 的p参数调小一点

def find_max(blobs):#找到视野中最大的小球，最大的色块
#因为视野中可能会有其他的小球，我们要追踪距离最近的那个小球
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.

    blobs = img.find_blobs([red_threshold])#调用颜色识别的函数
if blobs:#如果找到了色块
max_blob = find_max(blobs)
x_error = max_blob[5]-img.width()/2
h_error = max_blob[2]*max_blob[3]-size_threshold
#pid的差值，用于计算后面pid的参数
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(max_blob[0:4]) # rect
img.draw_cross(max_blob[5], max_blob[6]) # 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:#没有找到色块
car.run(18,-18)#让小车在原地以非常慢的速度旋转
#旋转可以在四周搜寻我们的小球

pid.py

from pyb import millis
from math import pi, isnan
#在后续的应用中直接调用即可

class PID:
_kp = _ki = _kd = _integrator = _imax = 0
_last_error = _last_derivative = _last_t = 0
_RC = 1/(2 * pi * 20)
def __init__(self, p=0, i=0, d=0, imax=0):
self._kp = float(p)
self._ki = float(i)
self._kd = float(d)
self._imax = abs(imax)
self._last_derivative = float('nan')

    def get_pid(self, error, scaler):
tnow = millis()
dt = tnow - self._last_t
output = 0
if self._last_t == 0 or dt > 1000:
dt = 0
self.reset_I()
self._last_t = tnow
delta_time = float(dt) / float(1000)
output += error * self._kp
if abs(self._kd) > 0 and dt > 0:
if isnan(self._last_derivative):
derivative = 0
self._last_derivative = 0
else:
derivative = (error - self._last_error) / delta_time
derivative = self._last_derivative + \
((delta_time / (self._RC + delta_time)) * \
(derivative - self._last_derivative))
self._last_error = error
self._last_derivative = derivative
output += self._kd * derivative
output *= scaler
if abs(self._ki) > 0 and dt > 0:
self._integrator += (error * self._ki) * scaler * delta_time
if self._integrator < -self._imax: self._integrator = -self._imax
elif self._integrator > self._imax: self._integrator = self._imax
output += self._integrator
return output
def reset_I(self):
self._integrator = 0
self._last_derivative = float('nan')

car.py

from pyb import Pin, Timer
inverse_left=False
inverse_right=False
ain1 =  Pin('P0', Pin.OUT_PP)
ain2 =  Pin('P1', Pin.OUT_PP)
bin1 =  Pin('P2', Pin.OUT_PP)
bin2 =  Pin('P3', Pin.OUT_PP)
ain1.low()
ain2.low()
bin1.low()
bin2.low()
pwma = Pin('P7')
pwmb = Pin('P8')
tim = Timer(4, freq=1000)
ch1 = tim.channel(1, Timer.PWM, pin=pwma)
ch2 = tim.channel(2, Timer.PWM, pin=pwmb)
ch1.pulse_width_percent(0)
ch2.pulse_width_percent(0)
def run(left_speed, right_speed):
    if inverse_left==True:
        left_speed=(-left_speed)
    if inverse_right==True:
        right_speed=(-right_speed)
    if left_speed < 0:
        ain1.low()
        ain2.high()
    else:
        ain1.high()
        ain2.low()
    ch1.pulse_width_percent(int(abs(left_speed)))
    if right_speed < 0:
        bin1.low()
        bin2.high()
    else:
        bin1.high()
        bin2.low()
    ch2.pulse_width_percent(int(abs(right_speed)))