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#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, Set_Point=0.0):
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=Set_Point
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
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