PID算法介绍
PID参数作用
位置式PID
增量式PID
PID离散化公式
PID算法公式
PID算法公式如下：
PWM (k) =PWM(k-1)+Kp*(T(k)-T(k-1))+Ki*(T(k)-Ttarget)+Kd*(T(k)-2*T(k-1)+T(k-2))
参数整定口诀
调试效果图
最终效果图
调试代码
from cProfile import label
import time
from turtle import width
import numpy as np
import matplotlib.pyplot as plt
from subprocess import PIPE, Popen, DEVNULL
from numpy import append
def run(cmd, retype="r"):
'''run System Command and Return Command Stdout Object'''
try:
with Popen(cmd, shell=True, stdout=PIPE, stderr=PIPE, encoding="utf-8") as f:
Ret_Type = {"r": f.stdout.read, "rl": f.stdout.readline, "rls" : f.stdout.readlines, "rc": f.wait}
if retype == 're':
return f.stdout.read() + f.stderr.read()
return Ret_Type[retype]()
except Exception as e:
print("\033[31mExecute Err:%s\033[0m"%e)
class DeltaPid(object):
'''
PID calculate
pwm = pre_pwm + kp*(err-pre_ee) + ki*err + kd*(err-2*pre_err+pre_pre_ee)
'''
def __init__(self, target_temp, max_pwm, min_pwm, p, i, d):
self.max_pwm = max_pwm
self.min_pwm = min_pwm
self.k_p = p
self.k_i = i
self.k_d = d
self.target_temp = target_temp
self._pre_temp = target_temp
self._pre_pre_temp = target_temp - 1
def calculate(self, cur_temp, pwm_in):
# pwm = pre_pwm + kp*(err-pre_ee) + ki*err + kd*(err-2*pre_err+pre_pre_ee)
pwm_out = 0
p_change = self.k_p * (cur_temp - self._pre_temp)
i_change = self.k_i * (cur_temp - self.target_temp)
d_change = self.k_d * (cur_temp - 2 * self._pre_temp + self._pre_pre_temp)
print(f"p:{p_change} i:{i_change} d:{d_change}")
delta_output = p_change + i_change + d_change
print(f"p+i+d output={delta_output}")
pwm_out = delta_output + pwm_in
print(f"calculate pwm={pwm_out}")
self._pre_pre_temp = self._pre_temp
self._pre_temp = cur_temp
pwm_out = self.max_pwm if pwm_out > self.max_pwm else (self.min_pwm if pwm_out < self.min_pwm else pwm_out )
print(f"actual output pwm={pwm_out}")
return pwm_out
class Pwm(object):
'''
function1: set and get fan and heater pwm
function2: get socket temp
'''
def __init__(self, path):
self.path = f"{path}"
self.fan_en = []
self.heater_en = []
self.fan_pwm = []
self.heater_pwm = []
self.temp = []
for i in range(1, 5):
self.fan_en.append(f"{self.path}fan{i}_en")
self.heater_en.append(f"{self.path}heater{i}_en")
self.fan_pwm.append(f"{self.path}fan{i}_pwm")
self.heater_pwm.append(f"{self.path}heater{i}_pwm")
self.temp.append(f"{self.path}temp{i}")
def en_fan(self, index):
cmd = f"echo 100 > {self.fan_en[index - 1]}"
run(cmd)
def en_heater(self, index):
cmd = f"echo 100 > {self.heater_en[index - 1]}"
run(cmd)
def get_temp(self, index):
cmd = f"cat {self.temp[index - 1]}"
return run(cmd).replace('\n', '')
def get_fan_pwm(self, index):
cmd = f"cat {self.fan_pwm[index - 1]}"
return run(cmd).replace('\n', '')
def set_fan_pwm(self, pwm, index):
cmd = f"echo {pwm} > {self.fan_pwm[index - 1]}"
run(cmd)
def get_heater_pwm(self, index):
cmd = f"cat {self.heater_pwm[index - 1]}"
return run(cmd).replace('\n', '')
def set_heater_pwm(self, pwm, index):
cmd = f"echo {pwm} > {self.heater_pwm[index - 1]}"
run(cmd)
def filter(index, limit):
usb_path = "/sys/dev/char/USB0/USB/"
pwm = Pwm(usb_path)
temp = []
for i in range(0, 7):
temp_old = int(pwm.get_temp(index))
temp_new = int(pwm.get_temp(index))
print(temp_old, temp_new)
if abs(temp_old - temp_new) < limit:
temp.append(temp_old)
temp.append(temp_new)
print(temp)
if not temp:
return int(pwm.get_temp(index))
return int(sum(temp)/len(temp))
def test(count=5000, target_temp = 105):
usb_path = "/sys/dev/char/USB0/USB/"
pwm = Pwm(usb_path)
counts = np.arange(count)
outputs = []
pwms = []
# enable fan and heater
pwm.en_fan(1)
pwm.en_heater(1)
# initial fan and heater pwm
pwm.set_fan_pwm(0, 1)
pwm.set_heater_pwm(100, 1)
pid = DeltaPid(target_temp, 45, 5, 10, 0.7, 0.3)
print(f"Now temp is {pwm.get_temp(1)}")
print("start test ...")
print(f"set heater pwm to 100, target temp is {target_temp} ...")
# set temp to (target) and keep heater in 80 pwm
print(f"time: {time.ctime()}")
while True:
temp1 = filter(1, 20)
print(f"Now temp is {temp1}")
time.sleep(1)
if temp1 / 10 >= (target_temp):
print("keep heater pwm to 80 ...")
pwm.set_fan_pwm(35, 1)
pwm.set_heater_pwm(80, 1)
break
# draw
print(f"time: {time.ctime()}")
for i in counts:
print(f"No.{i} pid adjust")
temp1 = filter(1, 20)
now_fan_pwm = int(pwm.get_fan_pwm(1))
pwms.append(now_fan_pwm)
print(f"temp={temp1}C , fan pwm={now_fan_pwm}")
now_pwm = pid.calculate(int(temp1) / 10, now_fan_pwm)
pwm.set_fan_pwm(int(now_pwm), 1)
time.sleep(1)
outputs.append(int(temp1) / 10)
print('Done')
# draw
plt.figure()
plt.axhline(target_temp, c='red', label = "target_temp")
plt.axhline(target_temp-3, c='yellow', label = "target_temp_min")
plt.axhline(target_temp+3, c='red', label = "target_temp_max")
plt.plot(counts, np.array(outputs), 'b.')
plt.ylim(0, 130)
plt.plot(counts, outputs, label = "temp")
plt.plot(counts, pwms, label = "pwm")
plt.title("PID")
plt.xlabel('count')
plt.ylabel('temperature')
plt.legend()
plt.tick_params(axis='both', width=1, length=5)
plt.xticks(fontsize=13)
plt.yticks(fontsize=13)
plt.show()
if __name__ == "__main__":
test()
