Encapsulates code that models an individual arbitrary force. More...

#include <FGExternalForce.h>

Inheritance diagram for FGExternalForce:

Collaboration diagram for FGExternalForce:

Public Member Functions
	FGExternalForce (FGFDMExec *FDMExec)
	Constructor. More...

	FGExternalForce (FGFDMExec FDMExec, Element el, int index)
	Constructor. More...

	FGExternalForce (const FGExternalForce &extForce)
	Copy Constructor. More...

	~FGExternalForce ()
	Destructor.

double	GetAzimuth (void) const

const FGColumnVector3 &	GetBodyForces (void)

double	GetLocX (void) const

double	GetLocY (void) const

double	GetLocZ (void) const

double	GetMagnitude (void) const

double	GetX (void) const

double	GetY (void) const

double	GetZ (void) const

void	SetAzimuth (double az)

void	SetLocX (double x)

void	SetLocY (double y)

void	SetLocZ (double z)

void	SetMagnitude (double mag)

void	SetX (double x)

void	SetY (double y)

void	SetZ (double z)

Public Member Functions inherited from FGForce
	FGForce (FGFDMExec *FDMExec)
	Constructor.

	FGForce (const FGForce &force)

	~FGForce ()
	Destructor.

const FGColumnVector3 &	GetActingLocation (void) const

double	GetActingLocationX (void) const

double	GetActingLocationY (void) const

double	GetActingLocationZ (void) const

const FGColumnVector3 &	GetAnglesToBody (void) const

double	GetAnglesToBody (int axis) const

double	GetBodyXForce (void) const

double	GetBodyYForce (void) const

double	GetBodyZForce (void) const

const FGColumnVector3 &	GetLocation (void) const

double	GetLocationX (void) const

double	GetLocationY (void) const

double	GetLocationZ (void) const

const FGColumnVector3 &	GetMoments (void) const

double	GetPitch (void) const

TransformType	GetTransformType (void) const

double	GetYaw (void) const

void	SetActingLocation (double x, double y, double z)
	Acting point of application. More...

void	SetActingLocation (const FGColumnVector3 &vv)

double	SetActingLocationX (double x)

double	SetActingLocationY (double y)

double	SetActingLocationZ (double z)

void	SetAnglesToBody (double broll, double bpitch, double byaw)

void	SetAnglesToBody (const FGColumnVector3 &vv)

void	SetLocation (double x, double y, double z)

void	SetLocation (const FGColumnVector3 &vv)

void	SetLocationX (double x)

void	SetLocationY (double y)

void	SetLocationZ (double z)

void	SetPitch (double pitch)

void	SetTransformType (TransformType ii)

void	SetYaw (double yaw)

const FGMatrix33 &	Transform (void) const

void	UpdateCustomTransformMatrix (void)

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

virtual	~FGJSBBase ()
	Destructor for FGJSBBase.

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

std::string	GetVersion (void)
	Returns the version number of JSBSim. More...

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

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

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

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

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

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

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

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

Additional Inherited Members
Public Types inherited from FGForce
enum	TransformType { tNone, tWindBody, tLocalBody, tCustom }

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

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

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

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

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

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

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

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

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

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

Static Public Member Functions inherited from FGJSBBase
static double	CelsiusToFahrenheit (double celsius)
	Converts from degrees Celsius to degrees Fahrenheit. More...

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

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

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

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

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

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

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

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

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

static double	GaussianRandomNumber (void)

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

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

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

static double	MachFromVcalibrated (double vcas, double p, double psl, double rhosl)
	Calculate the Mach number from the calibrated airspeed. More...

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

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

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

static double	sign (double num)

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

Static Public Attributes inherited from FGJSBBase
static short	debug_lvl = 1

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

Protected Member Functions inherited from FGJSBBase
void	Debug (int)

Static Protected Member Functions inherited from FGJSBBase
static std::string	CreateIndexedPropertyName (const std::string &Property, int index)

Protected Attributes inherited from FGForce
FGFDMExec *	fdmex

FGMatrix33	mT

TransformType	ttype

FGColumnVector3	vActingXYZn

FGColumnVector3	vFn

FGColumnVector3	vH

FGColumnVector3	vMn

FGColumnVector3	vOrient

FGColumnVector3	vXYZn

Static Protected Attributes inherited from FGJSBBase
static const double	degtorad = 0.017453292519943295769236907684886

static const double	fpstokts = 1.0/ktstofps

static const double	fttom = 0.3048

static int	gaussian_random_number_phase = 0

static const double	hptoftlbssec = 550.0

static const double	in3tom3 = 1.638706E-5

static const double	inchtoft = 0.08333333

static const double	inhgtopa = 3386.38

static const std::string	JSBSim_version = "1.0 " __DATE__ " " __TIME__

static const double	kgtolb = 2.20462

static const double	kgtoslug = 0.06852168

static const double	ktstofps = 1.68781

static const double	lbtoslug = 1.0/slugtolb

static Message	localMsg

static const double	m3toft3 = 1.0/(fttomfttomfttom)

static double	Mair = 28.9645

static unsigned int	messageId = 0

static std::queue< Message >	Messages

static const std::string	needed_cfg_version = "2.0"

static const double	psftoinhg = 0.014138

static const double	psftopa = 47.88

static const double	radtodeg = 57.295779513082320876798154814105

static double	Reng = 1716.56

static double	Rstar = 1545.348

static const double	SHRatio = 1.40

static const double	slugtolb = 32.174049

Detailed Description

Encapsulates code that models an individual arbitrary force.

This class encapsulates an individual force applied at the specified location on the vehicle, and oriented as specified in one of three frames:

BODY frame is defined with the X axis positive forward, the Y axis positive out the right wing, and the Z axis completing the set positive downward out the belly of the aircraft.
LOCAL frame is a world-based frame, with X positive north, Y positive east and Z completing the right handed system positive down towards the center of the Earth.
WIND frame (rotated) has X negative into the wind vector (in other words drag is along the positive X axis), the Z axis is perpendicular to X and positive up (lift) but in the aircraft XZ plane, and Y completes the right handed system. This is modified from a normal wind frame definition, which is rotated about the Y axis 180 degrees from this WIND frame.

Much of the substance of this class is located in the FGForce base class, from which this class is derived.

Here is the XML definition of a force (optional items are in []):

<force name="name" frame="BODY | LOCAL | WIND">
  
  [<function> ... </function>]
  <location unit="{IN | M}"> 
    <x> {number} </x>
    <y> {number} </y>
    <z> {number} </z>
  </location>
  [<direction> <!-- optional initial direction vector -->
    <x> {number} </x>
    <y> {number} </y>
    <z> {number} </z>
  </direction>]
</force>

The initial direction can optionally be set by specifying a unit vector in the chosen frame (body, local, or wind). The direction is specified at runtime through setting any/all of the following properties:

external_reactions/{force name}/x
external_reactions/{force name}/y
external_reactions/{force name}/z

As an example, a parachute can be defined oriented in the wind axis frame so the drag always acts in the drag direction - opposite the positive X axis. That does not include the effects of parachute oscillations, but those could be handled in the calling application.

The force direction is not actually required to be specified as a unit vector, but prior to the force vector being calculated, the direction vector is normalized.

The location of the force vector, in structural coordinates, can be set at runtime through the following properties:

external_reactions/{force name}/locx
external_reactions/{force name}/locy
external_reactions/{force name}/locz

Definition at line 140 of file FGExternalForce.h.

Constructor & Destructor Documentation

◆ FGExternalForce() [1/3]

FGExternalForce ( FGFDMExec * FDMExec )

Constructor.

Parameters

FDMExec pointer to the main executive class.

◆ FGExternalForce() [2/3]

FGExternalForce	(	FGFDMExec *	FDMExec,
		Element *	el,
		int	index
	)

Constructor.

Parameters

FDMExec	pointer to the main executive class.
el	pointer to the XML element defining an individual force.
index	the position of this force object in the whole list.

Definition at line 68 of file FGExternalForce.cpp.

   : FGForce(FDMExec)
 {
   Element* location_element=0;
   Element* direction_element=0;
   Element* function_element=0;
   string sFrame;
   string BasePropertyName;
   FGColumnVector3 location;
   Magnitude_Function = 0;
   magnitude = 0.0;
   azimuth = 0.0;
 
   FGPropertyManager* PropertyManager = fdmex->GetPropertyManager();
   Name = el->GetAttributeValue("name");
   BasePropertyName = "external_reactions/" + Name;
 
   // The value sent to the sim through the external_forces/{force name}/magnitude
   // property will be multiplied against the unit vector, which can come in
   // initially in the direction vector. The frame in which the vector is defined
   // is specified with the frame attribute. The vector is normalized to magnitude 1.
 
   function_element = el->FindElement("function");
   if (function_element) {
     Magnitude_Function = new FGFunction(PropertyManager, function_element);
   } else {
     PropertyManager->Tie( BasePropertyName + "/magnitude",(FGExternalForce*)this, &FGExternalForce::GetMagnitude, &FGExternalForce::SetMagnitude);
   }
 
 
   // Set frame (from FGForce).
   sFrame = el->GetAttributeValue("frame");
   if (sFrame.empty()) {
     cerr << "No frame specified for external force, \"" << Name << "\"." << endl;
     cerr << "Frame set to Body" << endl;
     ttype = tNone;
   } else if (sFrame == "BODY") {
     ttype = tNone;
   } else if (sFrame == "LOCAL") {
     ttype = tLocalBody;
     PropertyManager->Tie( BasePropertyName + "/azimuth", (FGExternalForce*)this, &FGExternalForce::GetAzimuth, &FGExternalForce::SetAzimuth);
   } else if (sFrame == "WIND") {
     ttype = tWindBody;
   } else {
     cerr << "Invalid frame specified for external force, \"" << Name << "\"." << endl;
     cerr << "Frame set to Body" << endl;
     ttype = tNone;
   }
   PropertyManager->Tie( BasePropertyName + "/x", (FGExternalForce*)this, &FGExternalForce::GetX, &FGExternalForce::SetX);
   PropertyManager->Tie( BasePropertyName + "/y", (FGExternalForce*)this, &FGExternalForce::GetY, &FGExternalForce::SetY);
   PropertyManager->Tie( BasePropertyName + "/z", (FGExternalForce*)this, &FGExternalForce::GetZ, &FGExternalForce::SetZ);
 
   location_element = el->FindElement("location");
   if (!location_element) {
     cerr << "No location element specified in force object." << endl;
   } else {
     location = location_element->FindElementTripletConvertTo("IN");
     SetLocation(location);
   }
   PropertyManager->Tie( BasePropertyName + "/location-x-in", (FGExternalForce*)this, &FGExternalForce::GetLocX, &FGExternalForce::SetLocX);
   PropertyManager->Tie( BasePropertyName + "/location-y-in", (FGExternalForce*)this, &FGExternalForce::GetLocY, &FGExternalForce::SetLocY);
   PropertyManager->Tie( BasePropertyName + "/location-z-in", (FGExternalForce*)this, &FGExternalForce::GetLocZ, &FGExternalForce::SetLocZ);
 
   direction_element = el->FindElement("direction");
   if (!direction_element) {
     cerr << "No direction element specified in force object. Default is (0,0,0)." << endl;
   } else {
     vDirection = direction_element->FindElementTripletConvertTo("IN");
     vDirection.Normalize();
   }
 
   Debug(0);
 }

Here is the call graph for this function:

◆ FGExternalForce() [3/3]

FGExternalForce ( const FGExternalForce & extForce )

Copy Constructor.

Parameters

extForce a reference to an existing FGExternalForce object

Definition at line 145 of file FGExternalForce.cpp.

                                                                 : FGForce(extForce)
 {
   magnitude = extForce.magnitude;
   Frame = extForce.Frame;
   vDirection = extForce.vDirection;
   Name = extForce.Name;
 }

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

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ FGExternalForce() [1/3]

◆ FGExternalForce() [2/3]

◆ FGExternalForce() [3/3]