SimScripts.PID.PID Class Reference

PID Controller. More...

Public Member Functions
def	__init__ (self, P=0.2, I=0.0, D=0.0, current_time=None)
def	clear (self)
	Clears PID computations and coefficients.
def	update (self, feedback_value, current_time=None)
	Calculates PID value for given reference feedback
def	setKp (self, proportional_gain)
	Determines how aggressively the PID reacts to the current error with setting Proportional Gain.
def	setKi (self, integral_gain)
	Determines how aggressively the PID reacts to the current error with setting Integral Gain.
def	setKd (self, derivative_gain)
	Determines how aggressively the PID reacts to the current error with setting Derivative Gain.
def	setWindup (self, windup)
	Integral windup, also known as integrator windup or reset windup, refers to the situation in a PID feedback controller where a large change in setpoint occurs (say a positive change) and the integral terms accumulates a significant error during the rise (windup), thus overshooting and continuing to increase as this accumulated error is unwound (offset by errors in the other direction).
def	setSampleTime (self, sample_time)
	PID that should be updated at a regular interval.

Public Attributes
	Kp
	Ki
	Kd
	sample_time
	current_time
	last_time
	SetPoint
	PTerm
	ITerm
	DTerm
	last_error
	int_error
	windup_guard
	output

Detailed Description

PID Controller.

Constructor & Destructor Documentation

__init__()

def SimScripts.PID.PID.__init__	(		self,
			P = 0.2,
			I = 0.0,
			D = 0.0,
			current_time = None
	)

Member Function Documentation

clear()

def SimScripts.PID.PID.clear

(

self

)

Clears PID computations and coefficients.

setKd()

def SimScripts.PID.PID.setKd	(		self,
			derivative_gain
	)

Determines how aggressively the PID reacts to the current error with setting Derivative Gain.

setKi()

def SimScripts.PID.PID.setKi	(		self,
			integral_gain
	)

Determines how aggressively the PID reacts to the current error with setting Integral Gain.

setKp()

def SimScripts.PID.PID.setKp	(		self,
			proportional_gain
	)

Determines how aggressively the PID reacts to the current error with setting Proportional Gain.

setSampleTime()

def SimScripts.PID.PID.setSampleTime	(		self,
			sample_time
	)

PID that should be updated at a regular interval.

Based on a pre-determined sampe time, the PID decides if it should compute or return immediately.

setWindup()

def SimScripts.PID.PID.setWindup	(		self,
			windup
	)

Integral windup, also known as integrator windup or reset windup, refers to the situation in a PID feedback controller where a large change in setpoint occurs (say a positive change) and the integral terms accumulates a significant error during the rise (windup), thus overshooting and continuing to increase as this accumulated error is unwound (offset by errors in the other direction).

The specific problem is the excess overshooting.

update()

def SimScripts.PID.PID.update	(		self,
			feedback_value,
			current_time = None
	)

Calculates PID value for given reference feedback

. math:: u(t) = K_p e(t) + K_i \int_{0}^{t} e(t)dt + K_d {de}/{dt} .. figure:: images/pid_1.png :align: center Test PID with Kp=1.2, Ki=1, Kd=0.001 (test_pid.py)

Member Data Documentation

current_time

SimScripts.PID.PID.current_time

DTerm

SimScripts.PID.PID.DTerm

int_error

SimScripts.PID.PID.int_error

ITerm

SimScripts.PID.PID.ITerm

Kd

SimScripts.PID.PID.Kd

Ki

SimScripts.PID.PID.Ki

Kp

SimScripts.PID.PID.Kp

last_error

SimScripts.PID.PID.last_error

last_time

SimScripts.PID.PID.last_time

output

SimScripts.PID.PID.output

PTerm

SimScripts.PID.PID.PTerm

sample_time

SimScripts.PID.PID.sample_time

SetPoint

SimScripts.PID.PID.SetPoint

windup_guard

SimScripts.PID.PID.windup_guard

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The documentation for this class was generated from the following file:

• lsvsim/simulationscripts/simScripts/src/hlcc/SimScripts/PID.py