openmv/scripts/libraries/pid.py
王开智 e763300b8b
library/pid.py change millis to ticks_ms
change pyb.millis to time.tick_ms, for supporting imx.rt
2024-03-13 13:15:27 +08:00

62 lines
1.9 KiB
Python

"""
Example:
from pid import PID
pid1 = PID(p=0.07, i=0, imax=90)
while(True):
error = 50 #error should be calculated, target - measure
output=pid1.get_pid(error,1)
#control value with output
"""
from time import ticks_ms
from math import pi, isnan
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 = ticks_ms()
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")