#The recipe gives simple implementation of a Discrete Proportional-Integral-Derivative (PID) controller. PID controller gives output value for error between desired reference input and measurement feedback to minimize error value. #More information: http://en.wikipedia.org/wiki/PID_controller # #cnr437@gmail.com # ####### Example ######### # #p=PID(3.0,0.4,1.2) #p.setPoint(5.0) #while True: # pid = p.update(measurement_value) # # class PID: """ Discrete PID control """ def __init__(self, P=2.0, I=0.0, D=1.0, Derivator=0, Integrator=0, Integrator_max=500, Integrator_min=-500): self.Kp=P self.Ki=I self.Kd=D self.Derivator=Derivator self.Integrator=Integrator self.Integrator_max=Integrator_max self.Integrator_min=Integrator_min self.set_point=0.0 self.error=0.0 def update(self,current_value): """ Calculate PID output value for given reference input and feedback """ self.error = self.set_point - current_value self.P_value = self.Kp * self.error self.D_value = self.Kd * ( self.error - self.Derivator) self.Derivator = self.error self.Integrator = self.Integrator + self.error if self.Integrator > self.Integrator_max: self.Integrator = self.Integrator_max elif self.Integrator < self.Integrator_min: self.Integrator = self.Integrator_min self.I_value = self.Integrator * self.Ki PID = self.P_value + self.I_value + self.D_value return PID def setPoint(self,set_point): """ Initilize the setpoint of PID """ self.set_point = set_point self.Integrator=0 self.Derivator=0 def setIntegrator(self, Integrator): self.Integrator = Integrator def setDerivator(self, Derivator): self.Derivator = Derivator def setKp(self,P): self.Kp=P def setKi(self,I): self.Ki=I def setKd(self,D): self.Kd=D def getPoint(self): return self.set_point def getError(self): return self.error def getIntegrator(self): return self.Integrator def getDerivator(self): return self.Derivator