""" 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 pyb import millis 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 = 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")