PID Class Reference

PID controller in parallel form implemented in floating-point arithmetic. Features Derivative-on-Measurement, anti-windup through conditional integration, bumpless transfer, and feed-forward. More...

#include <PID.h>

Public Member Functions
	PID (const double *pv, double *cv, const double *sp, double Kp, double Ki, double Kd, double Kf, uint16_t dt, double cvMin, double cvMax, double a)
	Constructor.
bool	compute ()
	Run a cycle of the PID loop.
void	setAuto (bool inAuto)
	Set the mode of the controller.
void	setGains (double Kp, double Ki, double Kd, double Kf, uint16_t dt)
	Set the gains and timestep.

Public Attributes
double	pTerm = 0
double	iTerm = 0
double	dTerm = 0
double	fTerm = 0
	PID terms.
double	cvMin
double	cvMax
	Lower/upper limits for cv.

Private Member Functions
void	init ()
	Method to be called when the controller goes from manual to auto mode for proper bumpless transfer.
double	clip (double value) const
	Clip value to [cvMin, cvMax].

Private Attributes
const double &	pv
	Process variable.
double &	cv
	Control variable.
const double &	sp
	Setpoint.
double	Kp
double	Ki
double	Kd
double	Kf
	Gains.
double	a
	Smoothing factor for EWA filter for derivative.
uint16_t	dt
	Timestep.
bool	inAuto = false
	Mode.
double	lastPv
	Last value of pv.
double	lastE
	Last value of error.
double	lastDPV
	Last value of derivative term.
double	integral
	Integral of pv.

Detailed Description

PID controller in parallel form implemented in floating-point arithmetic. Features Derivative-on-Measurement, anti-windup through conditional integration, bumpless transfer, and feed-forward.

Definition at line 8 of file PID.h.

Constructor & Destructor Documentation

PID()

PID::PID	(	const double *	pv,
		double *	cv,
		const double *	sp,
		double	Kp,
		double	Ki,
		double	Kd,
		double	Kf,
		uint16_t	dt,
		double	cvMin,
		double	cvMax,
		double	a )

Constructor.

Parameters

pv	Pointer to process variable
cv	Pointer to control value
sp	Pointer to setpoint
Kp	Proportional gain
Ki	Integral gain (in 1/s)
Kd	Derivative gain (in s)
Kf	Feed-forward gain
dt	Timestep (in ms)
cvMin	Lower limit for control value
cvMax	Upper limit for control value
a	Smoothing factor for EWA filter for derivative

Definition at line 3 of file PID.cpp.

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Member Function Documentation

clip()

double PID::clip ( double value ) const

private

Clip value to [cvMin, cvMax].

Parameters

value

Value to clip

Returns

Clipped value

Definition at line 44 of file PID.cpp.

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compute()

bool PID::compute

(

)

Run a cycle of the PID loop.

Returns

True if a PID step was run, and false if not.

Definition at line 17 of file PID.cpp.

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init()

void PID::init ( )

private

Method to be called when the controller goes from manual to auto mode for proper bumpless transfer.

Definition at line 9 of file PID.cpp.

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setAuto()

void PID::setAuto

(

bool

inAuto

)

Set the mode of the controller.

Parameters

inAuto

Set to true for automatic, false for manual.

Definition at line 52 of file PID.cpp.

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setGains()

void PID::setGains	(	double	Kp,
		double	Ki,
		double	Kd,
		double	Kf,
		uint16_t	dt )

Set the gains and timestep.

Parameters

Kp	Proportional gain
Ki	Integral gain (in 1/s)
Kd	Derivative gain (in s)
Kf	Feed-forward gain
dt	Timestep (in ms)

Definition at line 59 of file PID.cpp.

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Member Data Documentation

a

double PID::a

private

Smoothing factor for EWA filter for derivative.

Definition at line 15 of file PID.h.

cv

double& PID::cv

private

Control variable.

Definition at line 11 of file PID.h.

cvMax

double PID::cvMax

Lower/upper limits for cv.

Definition at line 34 of file PID.h.

cvMin

double PID::cvMin

Definition at line 34 of file PID.h.

dt

uint16_t PID::dt

private

Timestep.

Definition at line 16 of file PID.h.

dTerm

double PID::dTerm = 0

Definition at line 33 of file PID.h.

fTerm

double PID::fTerm = 0

PID terms.

Definition at line 33 of file PID.h.

inAuto

bool PID::inAuto = false

private

Mode.

Definition at line 18 of file PID.h.

integral

double PID::integral

private

Integral of pv.

Definition at line 22 of file PID.h.

iTerm

double PID::iTerm = 0

Definition at line 33 of file PID.h.

Kd

double PID::Kd

private

Definition at line 14 of file PID.h.

Kf

double PID::Kf

private

Gains.

Definition at line 14 of file PID.h.

Ki

double PID::Ki

private

Definition at line 14 of file PID.h.

Kp

double PID::Kp

private

Definition at line 14 of file PID.h.

lastDPV

double PID::lastDPV

private

Last value of derivative term.

Definition at line 21 of file PID.h.

lastE

double PID::lastE

private

Last value of error.

Definition at line 20 of file PID.h.

lastPv

double PID::lastPv

private

Last value of pv.

Definition at line 19 of file PID.h.

pTerm

double PID::pTerm = 0

Definition at line 33 of file PID.h.

pv

const double& PID::pv

private

Process variable.

Definition at line 10 of file PID.h.

sp

const double& PID::sp

private

Setpoint.

Definition at line 12 of file PID.h.

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

• src/control/PID.h
• src/control/PID.cpp