A generic PID controller. This can be used for any application that needs to handle oscillations using a PID controller. Specific examples using a PID controller are maintain velocity, heading, or position. More...

#include <pidcontroller.h>

Public Member Functions
	PIDController ()
	Constructor.
	~PIDController ()
	Destructor.
void	SetRate (const double dt=1.0)
	Set the update interval for PID constants.
double	UpdatePID (const double error)
	Uses error feedback to provide new input to the system.
void	SetOffset (const double offset)
	Sets any desired offset for calculating solution from the PID.
void	SetBounds (const double min, const double max)
	Sets boundaries for the solutions the PID can calculate.
void	SetGains (const double p, const double i, const double d)
	Sets the PID gain values of your controller.
void	ClearError ()
	Clears out any summed error.
void	Reset ()
	Sets all values back to defaults.
void	Reset (const double lower, const double upper, const double offset, const double p, const double i, const double d)
	Resets the sum of errors, and configures the controller based on the inputs.
double	GetProportionalGain () const
double	GetIntegralGrain () const
double	GetDifferentialGain () const
double	GetSumOfError () const
double	GetOffset () const
double	GetLowerBound () const
double	GetUpperBound () const
Protected Attributes
double	mPreviousError
	Previous error of system.
double	mPreviousSolution
	Previous feedback result (used with upper and lower bounds to prevent winding)
double	mP
	Proportional Gain.
double	mI
	Integral Gain.
double	mD
	Differential Gain.
double	mSumOfError
	Sum of error.
double	mOffset
	Offset to add onto solution (default 0)
double	mUpperBound
	Upper bound on solution (prevents winding/large sum of errors) default is INFINITE.
double	mLowerBound
	Lower bound on solution (prevents winding/large sum of erros) default is -INFINITE.
double	mDT
	DT term.

Detailed Description

A generic PID controller. This can be used for any application that needs to handle oscillations using a PID controller. Specific examples using a PID controller are maintain velocity, heading, or position.

This controller does not calculate the error for your specific application, instead it takes the error as an argument to the UpdatePID function, which returns the new solution to use in your closed loop process.

Definition at line 62 of file pidcontroller.h.

Constructor & Destructor Documentation

PIDController::PIDController ( )

Constructor.

Definition at line 52 of file pidcontroller.cpp.

PIDController::~PIDController ( )

Destructor.

Definition at line 65 of file pidcontroller.cpp.

Member Function Documentation

void PIDController::ClearError ( )

Clears out any summed error.

Definition at line 200 of file pidcontroller.cpp.

double CxUtils::PIDController::GetDifferentialGain ( ) const [inline]

Definition at line 94 of file pidcontroller.h.

double CxUtils::PIDController::GetIntegralGrain ( ) const [inline]

Definition at line 93 of file pidcontroller.h.

double CxUtils::PIDController::GetLowerBound ( ) const [inline]

Definition at line 97 of file pidcontroller.h.

double CxUtils::PIDController::GetOffset ( ) const [inline]

Definition at line 96 of file pidcontroller.h.

double CxUtils::PIDController::GetProportionalGain ( ) const [inline]

Definition at line 92 of file pidcontroller.h.

double CxUtils::PIDController::GetSumOfError ( ) const [inline]

Definition at line 95 of file pidcontroller.h.

double CxUtils::PIDController::GetUpperBound ( ) const [inline]

Definition at line 98 of file pidcontroller.h.

void PIDController::Reset	(	const double	lower,
		const double	upper,
		const double	offset,
		const double	p,
		const double	i,
		const double	d
	)

Resets the sum of errors, and configures the controller based on the inputs.

Parameters:

lower	Lower bound of system inputs
upper	Upper bound of system inputs
offset	Offset to add to system input solutions
p	The proportional gain
i	The integral gain
d	The derivative gain

Definition at line 239 of file pidcontroller.cpp.

void PIDController::Reset ( )

Sets all values back to defaults.

Definition at line 211 of file pidcontroller.cpp.

void PIDController::SetBounds	(	const double	min,
		const double	max
	)

Sets boundaries for the solutions the PID can calculate.

For example, if the inputs you want to provide your system are between [-100,100], then your offset would be 0, and you would have upper and lower bounds of [-100,100]. If your system was [50, 150], you would have an offset of 50, with upper and lower bounds of [50,150].

Parameters:

min	The lower bound of your system inputs
max	The upper bound of your system inputs

Definition at line 164 of file pidcontroller.cpp.

void PIDController::SetGains	(	const double	p,
		const double	i,
		const double	d
	)

Sets the PID gain values of your controller.

By adjusting these values you can increase or decrease the performance of the PID controller. You should have a limited understanding of how to adjust these values before doing so.

Parameters:

p	The proportional gain
i	The integral gain
d	The derivative gain

Definition at line 187 of file pidcontroller.cpp.

void PIDController::SetOffset ( const double offset )

Sets any desired offset for calculating solution from the PID.

For example, if the inputs you want to provide your system are between [-100,100], then your offset would be 0, and you would have upper and lower bounds of [-100,100]. If your system was [50, 150], you would have an offset of 50, with upper and lower bounds of [50,150].

Parameters:

offset The offset to add to the PID solutions.

Definition at line 145 of file pidcontroller.cpp.

void PIDController::SetRate ( const double dt = 1.0 )

Set the update interval for PID constants.

Parameters:

[in] dt Delta Time variable for PID calculations, default is 1.

Definition at line 77 of file pidcontroller.cpp.

double PIDController::UpdatePID ( const double error )

Uses error feedback to provide new input to the system.

This function performs the calculations of the PID controller. It checks to make sure the returned value is within the bounds of the maximum and minimum values your system can take. The upper and lower bounds can be set using the setBounds function.

The error provided should be the error of your system between desired and actual. This controller does not calculate error so that it can be kept generic. The results of this function are only as good as the PID gain values that model your system.

Parameters:

error The feedback error of the system.