FlightGear: JSBSim::FGExternalReactions Class Reference

Manages the external and/or arbitrary forces and moments. More...

#include <FGExternalReactions.h>

Public Member Functions
	FGExternalReactions (FGFDMExec *fdmex)
	Constructor.

	~FGExternalReactions (void) override
	Destructor.

bool	InitModel (void) override

bool	Run (bool Holding) override
	Sum all the constituent forces for this cycle.

bool	Load (Element *el) override
	Loads the external forces from the XML configuration file.

const FGColumnVector3 &	GetForces (void) const
	Retrieves the total forces defined in the external reactions.

double	GetForces (int idx) const

const FGColumnVector3 &	GetMoments (void) const
	Retrieves the total moment resulting from the forces defined in the external reactions.

double	GetMoments (int idx) const

Public Member Functions inherited from JSBSim::FGModel
	FGModel (FGFDMExec *)
	Constructor.

	~FGModel () override
	Destructor.

bool	InitModel (void) override

void	SetRate (unsigned int tt)
	Set the ouput rate for the model in frames.

unsigned int	GetRate (void)
	Get the output rate for the model in frames.

FGFDMExec *	GetExec (void)

void	SetPropertyManager (FGPropertyManager *fgpm)

virtual SGPath	FindFullPathName (const SGPath &path) const

const std::string &	GetName (void)

Public Member Functions inherited from JSBSim::FGModelFunctions
virtual	~FGModelFunctions ()

void	RunPreFunctions (void)

void	RunPostFunctions (void)

bool	Load (Element el, FGFDMExec fdmex, std::string prefix="")

void	PreLoad (Element el, FGFDMExec fdmex, std::string prefix="")

void	PostLoad (Element el, FGFDMExec fdmex, std::string prefix="")

std::string	GetFunctionStrings (const std::string &delimeter) const
	Gets the strings for the current set of functions.

std::string	GetFunctionValues (const std::string &delimeter) const
	Gets the function values.

FGFunction *	GetPreFunction (const std::string &name)
	Get one of the "pre" function.

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
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...

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::FGModel
bool	Upload (Element *el, bool preLoad)
	Uploads this model in memory.

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

Protected Attributes inherited from JSBSim::FGModel
unsigned int	exe_ctr

unsigned int	rate

std::string	Name

FGFDMExec *	FDMExec

FGPropertyManager *	PropertyManager

Protected Attributes inherited from JSBSim::FGModelFunctions
std::vector< FGFunction * >	PreFunctions

std::vector< FGFunction * >	PostFunctions

FGPropertyReader	LocalProperties

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

Manages the external and/or arbitrary forces and moments.

The external reactions capability in JSBSim really should be named "arbitrary forces and moments", because this feature can be used to model a wide variety of forces and moments that act on a vehicle. Some examples include: parachutes, catapult, arresting hook, and tow line.

This class acts similarly to the other "manager classes" (FGPropulsion, FGFCS, FGGroundReactions, FGAerodynamics) because it manages collections of constituent elements. The individual forces and moments are implemented with the FGExternalForce class.

The format of the optional external reactions section in the config file is as follows:

<external_reactions>
 
  <!-- Interface properties, a.k.a. property declarations -->
  <property> ... </property>
    
  <force name="name" frame="BODY | LOCAL | WIND">
    ...
  </force>
  <moment name="name" frame="BODY | LOCAL | WIND">
    ...
  </moment>
 
  <!-- Additional force and moment definitions may follow -->
  <force name="name" frame="BODY | LOCAL | WIND">
    ...
  </force>
  <moment name="name" frame="BODY | LOCAL | WIND">
    ...
  </moment>
 
</external_reactions>

See the FGExternalForce class for more information on the format of the force and moment specifications.

When force or moment elements are encountered in the configuration file, a new instance of the FGExternalForce class is created and a pointer to the class is pushed onto the Forces vector.

This class is one of a few of the manager classes that allows properties to be "declared". In code, these are represented by the interface_properties vector. Properties that have not yet been created in an already parsed section of the configuration file and that are used in the definition of an external force or moment should be declared in the external_reactions section because they will not be created automatically, and so would cause an error, since the property cannot be found to exist.

See the FGExternalForce documentation for details on how forces and moments are actually calculated.

Definition at line 121 of file FGExternalReactions.h.

Constructor & Destructor Documentation

◆ FGExternalReactions()

JSBSim::FGExternalReactions::FGExternalReactions ( FGFDMExec * fdmex )

Constructor.

Parameters

fdmex pointer to the main executive class.

Definition at line 51 of file FGExternalReactions.cpp.

◆ ~FGExternalReactions()

JSBSim::FGExternalReactions::~FGExternalReactions ( void )

override

Destructor.

Within the destructor the Forces and interface_properties vectors are cleared out and the items pointed to are deleted.

Definition at line 93 of file FGExternalReactions.cpp.

Member Function Documentation

◆ GetForces() [1/2]

double JSBSim::FGExternalReactions::GetForces ( int idx ) const

inline

Definition at line 158 of file FGExternalReactions.h.

◆ GetForces() [2/2]

const FGColumnVector3 & JSBSim::FGExternalReactions::GetForces ( void ) const

inline

Retrieves the total forces defined in the external reactions.

Returns: the total force in pounds.

Definition at line 157 of file FGExternalReactions.h.

◆ GetMoments() [1/2]

double JSBSim::FGExternalReactions::GetMoments ( int idx ) const

inline

Definition at line 164 of file FGExternalReactions.h.

◆ GetMoments() [2/2]

const FGColumnVector3 & JSBSim::FGExternalReactions::GetMoments ( void ) const

inline

Retrieves the total moment resulting from the forces defined in the external reactions.

Returns: the total moment in foot-pounds.

Definition at line 163 of file FGExternalReactions.h.

◆ InitModel()

bool JSBSim::FGExternalReactions::InitModel ( void )

overridevirtual

Reimplemented from JSBSim::FGModelFunctions.

Definition at line 102 of file FGExternalReactions.cpp.

◆ Load()

bool JSBSim::FGExternalReactions::Load ( Element * el )

overridevirtual

Loads the external forces from the XML configuration file.

If the external_reactions section is encountered in the vehicle configuration file, this Load() method is called. All external forces will be parsed, and a FGExternalForce object will be instantiated for each force definition.

Parameters

el	a pointer to the XML element holding the external reactions definition.

Reimplemented from JSBSim::FGModel.

Definition at line 58 of file FGExternalReactions.cpp.

◆ Run()

bool JSBSim::FGExternalReactions::Run ( bool Holding )

overridevirtual

Sum all the constituent forces for this cycle.

Can pass in a value indicating if the executive is directing the simulation to Hold.

Parameters

Holding if true, the executive has been directed to hold the sim from advancing time. Some models may ignore this flag, such as the Input model, which may need to be active to listen on a socket for the "Resume" command to be given.

Returns: true always.

Reimplemented from JSBSim::FGModel.

Definition at line 114 of file FGExternalReactions.cpp.

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

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ FGExternalReactions()

◆ ~FGExternalReactions()

Member Function Documentation

◆ GetForces() [1/2]

◆ GetForces() [2/2]

◆ GetMoments() [1/2]

◆ GetMoments() [2/2]

◆ InitModel()

◆ Load()

◆ Run()