FlightGear: JSBSim::FGPID Class Reference

Encapsulates a PID control component for the flight control system. More...

#include <FGPID.h>

Public Types
enum	eIntegrateType { eNone = 0 , eRectEuler , eTrapezoidal , eAdamsBashforth2 , eAdamsBashforth3 }
	These define the indices use to select the various integrators. More...

Public Types inherited from JSBSim::FGJSBBase
enum	{ eL = 1 , eM , eN }
	Moments L, M, N. More...

enum	{ eP = 1 , eQ , eR }
	Rates P, Q, R. More...

enum	{ eU = 1 , eV , eW }
	Velocities U, V, W. More...

enum	{ eX = 1 , eY , eZ }
	Positions X, Y, Z. More...

enum	{ ePhi = 1 , eTht , ePsi }
	Euler angles Phi, Theta, Psi. More...

enum	{ eDrag = 1 , eSide , eLift }
	Stability axis forces, Drag, Side force, Lift. More...

enum	{ eRoll = 1 , ePitch , eYaw }
	Local frame orientation Roll, Pitch, Yaw. More...

enum	{ eNorth = 1 , eEast , eDown }
	Local frame position North, East, Down. More...

enum	{ eLat = 1 , eLong , eRad }
	Locations Radius, Latitude, Longitude. More...

enum	{ inNone = 0 , inDegrees , inRadians , inMeters , inFeet }
	Conversion specifiers. More...

Public Member Functions
	FGPID (FGFCS fcs, Element element)

	~FGPID ()

bool	Run (void) override

void	ResetPastStates (void) override

void	SetInitialOutput (double val)

Public Member Functions inherited from JSBSim::FGFCSComponent
	FGFCSComponent (FGFCS fcs, Element el)
	Constructor.

virtual	~FGFCSComponent ()
	Destructor.

virtual void	SetOutput (void)

double	GetOutput (void) const

std::string	GetName (void) const

std::string	GetType (void) const

virtual double	GetOutputPct (void) const

Public Member Functions inherited from JSBSim::FGJSBBase
	FGJSBBase ()
	Constructor for FGJSBBase.

virtual	~FGJSBBase ()
	Destructor for FGJSBBase.

void	PutMessage (const Message &msg)
	Places a Message structure on the Message queue.

void	PutMessage (const std::string &text)
	Creates a message with the given text and places it on the queue.

void	PutMessage (const std::string &text, bool bVal)
	Creates a message with the given text and boolean value and places it on the queue.

void	PutMessage (const std::string &text, int iVal)
	Creates a message with the given text and integer value and places it on the queue.

void	PutMessage (const std::string &text, double dVal)
	Creates a message with the given text and double value and places it on the queue.

int	SomeMessages (void) const
	Reads the message on the queue (but does not delete it).

void	ProcessMessage (void)
	Reads the message on the queue and removes it from the queue.

Message *	ProcessNextMessage (void)
	Reads the next message on the queue and removes it from the queue.

void	disableHighLighting (void)
	Disables highlighting in the console output.

Additional Inherited Members
static const std::string &	GetVersion (void)
	Returns the version number of JSBSim.

static constexpr double	KelvinToFahrenheit (double kelvin)
	Converts from degrees Kelvin to degrees Fahrenheit.

static constexpr double	CelsiusToRankine (double celsius)
	Converts from degrees Celsius to degrees Rankine.

static constexpr double	RankineToCelsius (double rankine)
	Converts from degrees Rankine to degrees Celsius.

static constexpr double	KelvinToRankine (double kelvin)
	Converts from degrees Kelvin to degrees Rankine.

static constexpr double	RankineToKelvin (double rankine)
	Converts from degrees Rankine to degrees Kelvin.

static constexpr double	FahrenheitToCelsius (double fahrenheit)
	Converts from degrees Fahrenheit to degrees Celsius.

static constexpr double	CelsiusToFahrenheit (double celsius)
	Converts from degrees Celsius to degrees Fahrenheit.

static constexpr double	CelsiusToKelvin (double celsius)
	Converts from degrees Celsius to degrees Kelvin.

static constexpr double	KelvinToCelsius (double kelvin)
	Converts from degrees Kelvin to degrees Celsius.

static constexpr double	FeetToMeters (double measure)
	Converts from feet to meters.

static double	PitotTotalPressure (double mach, double p)
	Compute the total pressure in front of the Pitot tube.

static double	MachFromImpactPressure (double qc, double p)
	Compute the Mach number from the differential pressure (qc) and the static pressure.

static double	VcalibratedFromMach (double mach, double p)
	Calculate the calibrated airspeed from the Mach number.

static double	MachFromVcalibrated (double vcas, double p)
	Calculate the Mach number from the calibrated airspeed.Based on the formulas in the US Air Force Aircraft Performance Flight Testing Manual (AFFTC-TIH-99-01).

static bool	EqualToRoundoff (double a, double b)
	Finite precision comparison.

static bool	EqualToRoundoff (float a, float b)
	Finite precision comparison.

static bool	EqualToRoundoff (float a, double b)
	Finite precision comparison.

static bool	EqualToRoundoff (double a, float b)
	Finite precision comparison.

static constexpr double	Constrain (double min, double value, double max)
	Constrain a value between a minimum and a maximum value.

static constexpr double	sign (double num)

static double	GaussianRandomNumber (void)

Static Public Attributes inherited from JSBSim::FGJSBBase
static char	highint [5] = {27, '[', '1', 'm', '\0' }
	highlights text

static char	halfint [5] = {27, '[', '2', 'm', '\0' }
	low intensity text

static char	normint [6] = {27, '[', '2', '2', 'm', '\0' }
	normal intensity text

static char	reset [5] = {27, '[', '0', 'm', '\0' }
	resets text properties

static char	underon [5] = {27, '[', '4', 'm', '\0' }
	underlines text

static char	underoff [6] = {27, '[', '2', '4', 'm', '\0' }
	underline off

static char	fgblue [6] = {27, '[', '3', '4', 'm', '\0' }
	blue text

static char	fgcyan [6] = {27, '[', '3', '6', 'm', '\0' }
	cyan text

static char	fgred [6] = {27, '[', '3', '1', 'm', '\0' }
	red text

static char	fggreen [6] = {27, '[', '3', '2', 'm', '\0' }
	green text

static char	fgdef [6] = {27, '[', '3', '9', 'm', '\0' }
	default text

static short	debug_lvl = 1

Protected Member Functions inherited from JSBSim::FGFCSComponent
void	Delay (void)

void	Clip (void)

void	CheckInputNodes (size_t MinNodes, size_t MaxNodes, Element *el)

static std::string	CreateIndexedPropertyName (const std::string &Property, int index)

Protected Attributes inherited from JSBSim::FGFCSComponent
FGFCS *	fcs

FGPropertyManager *	PropertyManager

std::vector< FGPropertyNode_ptr >	OutputNodes

FGParameter_ptr	ClipMin

FGParameter_ptr	ClipMax

std::vector< FGPropertyValue_ptr >	InitNodes

std::vector< FGPropertyValue_ptr >	InputNodes

std::vector< double >	output_array

std::string	Type

std::string	Name

double	Input

double	Output

double	delay_time

unsigned int	delay

int	index

double	dt

bool	clip

bool	cyclic_clip

static Message	localMsg

static std::queue< Message >	Messages

static unsigned int	messageId = 0

static constexpr double	radtodeg = 180. / 3.14159265358979323846

static constexpr double	degtorad = 3.14159265358979323846 / 180.

static constexpr double	hptoftlbssec = 550.0

static constexpr double	psftoinhg = 0.014138

static constexpr double	psftopa = 47.88

static constexpr double	ktstofps = 1.68781

static constexpr double	fpstokts = 1.0 / ktstofps

static constexpr double	inchtoft = 1.0/12.0

static constexpr double	fttom = 0.3048

static constexpr double	m3toft3 = 1.0/(fttomfttomfttom)

static constexpr double	in3tom3 = inchtoftinchtoftinchtoft/m3toft3

static constexpr double	inhgtopa = 3386.38

static constexpr double	slugtolb = 32.174049
	Note that definition of lbtoslug by the inverse of slugtolb and not to a different constant you can also get from some tables will make lbtoslug*slugtolb == 1 up to the magnitude of roundoff.

static constexpr double	lbtoslug = 1.0/slugtolb

static constexpr double	kgtolb = 2.20462

static constexpr double	kgtoslug = 0.06852168

static const std::string	needed_cfg_version = "2.0"

static const std::string	JSBSim_version = JSBSIM_VERSION " " __DATE__ " " __TIME__

static int	gaussian_random_number_phase = 0

Detailed Description

Encapsulates a PID control component for the flight control system.

Configuration Format:

<pid name="{string}" [type="standard"]>
  <input> {[-]property} </input>
  <kp> {number|[-]property} </kp>
  <ki type="rect|trap|ab2|ab3"> {number|[-]property} </ki>
  <kd> {number|[-]property} </kd>
  <trigger> {property} </trigger>
  <pvdot> {property} </pvdot>
</pid>

For the integration constant element, one can also supply the type attribute for what kind of integrator to be used, one of:

rect, for a rectangular integrator
trap, for a trapezoidal integrator
ab2, for a second order Adams Bashforth integrator
ab3, for a third order Adams Bashforth integrator

For example,

<pid name="fcs/heading-control">
  <input> fcs/heading-error </input>
  <kp> 3 </kp>
  <ki type="ab3"> 1 </ki>
  <kd> 1 </kd>
</pid>

Configuration Parameters:

The values of kp, ki, and kd have slightly different interpretations depending on whether the PID controller is a standard one, or an ideal/parallel one - with the latter being the default.

By default, the PID controller computes the derivative as being the slope of the line joining the value of the previous input to the value of the current input. However if a better estimation can be determined for the derivative, you can provide its value to the PID controller via the property supplied in pvdot.

kp - Proportional constant, default value 0. ki - Integrative constant, default value 0. kd - Derivative constant, default value 0. trigger - Property which is used to sense wind-up, optional. Most often, the trigger will be driven by the "saturated" property of a particular actuator. When the relevant actuator has reached it's limits (if there are any, specified by the <clipto> element) the automatically generated saturated property will be greater than zero (true). If this property is used as the trigger for the integrator, the integrator will not continue to integrate while the property is still true (> 1), preventing wind-up. The integrator can also be reset to 0.0 if the property is set to a negative value. pvdot - The property to be used as the process variable time derivative.

Author: Jon S. Berndt

Definition at line 125 of file FGPID.h.

Member Enumeration Documentation

◆ eIntegrateType

enum JSBSim::FGPID::eIntegrateType

These define the indices use to select the various integrators.

Enumerator
eNone
eRectEuler
eTrapezoidal
eAdamsBashforth2
eAdamsBashforth3

Definition at line 135 of file FGPID.h.

Constructor & Destructor Documentation

◆ FGPID()

JSBSim::FGPID::FGPID	(	FGFCS *	fcs,
		Element *	element )

Definition at line 49 of file FGPID.cpp.

◆ ~FGPID()

JSBSim::FGPID::~FGPID ( )

Definition at line 131 of file FGPID.cpp.

Member Function Documentation

◆ ResetPastStates()

void JSBSim::FGPID::ResetPastStates ( void )

overridevirtual

Reimplemented from JSBSim::FGFCSComponent.

Definition at line 143 of file FGPID.cpp.

◆ Run()

bool JSBSim::FGPID::Run ( void )

overridevirtual

Reimplemented from JSBSim::FGFCSComponent.

Definition at line 152 of file FGPID.cpp.

◆ SetInitialOutput()

void JSBSim::FGPID::SetInitialOutput ( double val )

inline

Definition at line 138 of file FGPID.h.

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

Public Types

Public Member Functions

Additional Inherited Members