Detailed Description

Manages ground reactions modeling.

Maintains a list of landing gear and ground contact points, all instances of FGLGear. Sums their forces and moments so that these may be provided to FGPropagate. Parses the <ground_reactions> section of the aircraft configuration file.

Configuration File Format of <ground_reactions> Section:

<ground_reactions>
    <contact>
       ... {see FGLGear for specifics of this format}
    </contact>
    ... {more contacts}
</ground_reactions>

Definition at line 79 of file FGGroundReactions.h.

#include <FGGroundReactions.h>

Inheritance diagram for FGGroundReactions:

Collaboration diagram for FGGroundReactions:

Public Member Functions
	FGGroundReactions (FGFDMExec *)

double	GetDsCmd (void) const
	Gets the steering command.

double	GetForces (int idx) const

const FGColumnVector3 &	GetForces (void) const

auto	GetGearUnit (int gear) const
	Gets a gear instance.

std::string	GetGroundReactionStrings (std::string delimeter) const

std::string	GetGroundReactionValues (std::string delimeter) const

double	GetMoments (int idx) const

const FGColumnVector3 &	GetMoments (void) const

std::vector< LagrangeMultiplier * > *	GetMultipliersList (void)

int	GetNumGearUnits (void) const
	Gets the number of gears.

bool	GetWOW (void) const

bool	InitModel (void) override

bool	Load (Element *el) override

void	RegisterLagrangeMultiplier (LagrangeMultiplier *lmult)

bool	Run (bool Holding) override
	Runs the Ground Reactions model; called by the Executive Can pass in a value indicating if the executive is directing the simulation to Hold.

void	SetDsCmd (double cmd)
	Sets the steering command.

Public Member Functions inherited from FGModel
	FGModel (FGFDMExec *, const std::string &name)
	Constructor.

	~FGModel () override
	Destructor.

virtual SGPath	FindFullPathName (const SGPath &path) const

FGFDMExec *	GetExec (void) const

const std::string &	GetName (void) const

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

bool	InitModel (void) override

void	SetPropertyManager (std::shared_ptr< FGPropertyManager > fgpm)

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

Public Member Functions inherited from FGModelFunctions
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.

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

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

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

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

void	RunPostFunctions (void)

void	RunPreFunctions (void)

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

virtual	~FGJSBBase ()
	Destructor for FGJSBBase.

Public Member Functions inherited from FGSurface
	FGSurface (FGFDMExec *fdmex)
	Constructor.

void	bind (FGPropertyManager *pm)

double	GetBumpHeight ()
	Returns the height of the bump at the provided offset.

double	GetBumpiness (void)
	Gets the normalized bumpiness factor associated with the surface.

double	GetMaximumForce (void)
	Gets the maximum force of the surface area.

double	GetRollingFFactor (void)
	Gets the rolling friction factor of the surface area.

bool	GetSolid (void)
	Gets the surface is a solid flag value.

double	GetStaticFFactor (void)
	Gets the static friction factor of the surface area.

void	resetValues (void)
	Reset all surface values to a default.

void	SetBumpiness (double bump)
	Sets the normalized bumpiness factor associated with the surface.

void	SetMaximumForce (double force)
	Sets the maximum force for the surface area.

void	SetPosition (const double pt[3])
	Set the currect position for bumpiness calulcation.

void	SetRollingFFactor (double friction)
	Sets the rolling friction factor of the surface area.

void	SetSolid (bool solid)
	Sets the surface is a solid flag value.

void	SetStaticFFactor (double friction)
	Sets the static friction factor of the surface area.

Public Attributes
FGLGear::Inputs	in

Additional Inherited Members
Public Types inherited from 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 Public Member Functions inherited from FGJSBBase
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	CelsiusToRankine (double celsius)
	Converts from degrees Celsius to degrees Rankine.

static constexpr 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.

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

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

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

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

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

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

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

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

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

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

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

static constexpr double	sign (double num)

Static Public Attributes inherited from FGJSBBase
static short	debug_lvl = 1

Protected Member Functions inherited from FGModel
bool	Upload (Element *el, bool preLoad)
	Uploads this model in memory.

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

Protected Attributes inherited from FGModel
bool	enabled = true

unsigned int	exe_ctr

FGFDMExec *	FDMExec

std::string	Name

std::shared_ptr< FGPropertyManager >	PropertyManager

unsigned int	rate

Protected Attributes inherited from FGModelFunctions
FGPropertyReader	LocalProperties

std::vector< std::shared_ptr< FGFunction > >	PostFunctions

std::vector< std::shared_ptr< FGFunction > >	PreFunctions

Protected Attributes inherited from FGSurface
double	bumpiness

bool	isSolid

double	maximumForce

double	rollingFFactor

double	staticFFactor

Static Protected Attributes inherited from FGJSBBase
static constexpr double	degtorad = M_PI / 180.

static constexpr double	fpstokts = 1.0 / ktstofps

static constexpr double	fttom = 0.3048

static constexpr double	hptoftlbssec = 550.0

static constexpr double	in3tom3 = inchtoftinchtoftinchtoft/m3toft3

static constexpr double	inchtoft = 1.0/12.0

static constexpr double	inhgtopa = 3386.38

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

static constexpr double	kgtolb = 2.20462

static constexpr double	kgtoslug = 0.06852168

static constexpr double	ktstofps = 1852./(3600*fttom)

static constexpr double	lbtoslug = 1.0/slugtolb

static constexpr double	m3toft3 = 1.0/(fttomfttomfttom)

static const std::string	needed_cfg_version = "2.0"

static constexpr double	psftoinhg = 0.014138

static constexpr double	psftopa = 47.88

static constexpr double	radtodeg = 180. / M_PI

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.

Constructor & Destructor Documentation

◆ FGGroundReactions()

FGGroundReactions ( FGFDMExec * fgex )

Definition at line 54 of file FGGroundReactions.cpp.

                                                    :
   FGModel(fgex, "FGGroundReactions"),
   FGSurface(fgex),
   DsCmd(0.0)
{
  bind();
 
  Debug(0);
}

Member Function Documentation

◆ GetDsCmd()

double GetDsCmd ( void ) const

inline

Gets the steering command.

Returns: steering command in range from -1.0 - 1.0

Definition at line 113 of file FGGroundReactions.h.

113{ return DsCmd; }

◆ GetForces() [1/2]

double GetForces ( int idx ) const

inline

Definition at line 95 of file FGGroundReactions.h.

95{return vForces(idx);}

◆ GetForces() [2/2]

const FGColumnVector3 & GetForces ( void ) const

inline

Definition at line 94 of file FGGroundReactions.h.

94{return vForces;}

◆ GetGearUnit()

auto GetGearUnit ( int gear ) const

inline

Gets a gear instance.

Parameters

gear	index of gear instance

Returns: a pointer to the FGLGear instance of the gear unit requested

Definition at line 109 of file FGGroundReactions.h.

109{ return lGear[gear]; }

◆ GetGroundReactionStrings()

string GetGroundReactionStrings ( std::string delimeter ) const

Definition at line 158 of file FGGroundReactions.cpp.

{
  std::ostringstream buf;
 
  for (auto& gear:lGear) {
    string name = gear->GetName();
    if (gear->IsBogey()) {
      buf << name << " WOW" << delimeter
          << name << " stroke (ft)" << delimeter
          << name << " stroke velocity (ft/sec)" << delimeter
          << name << " compress force (lbs)" << delimeter
          << name << " wheel side force (lbs)" << delimeter
          << name << " wheel roll force (lbs)" << delimeter
          << name << " body X force (lbs)" << delimeter
          << name << " body Y force (lbs)" << delimeter
          << name << " wheel velocity vec X (ft/sec)" << delimeter
          << name << " wheel velocity vec Y (ft/sec)" << delimeter
          << name << " wheel rolling velocity (ft/sec)" << delimeter
          << name << " wheel side velocity (ft/sec)" << delimeter
          << name << " wheel slip (deg)" << delimeter;
    } else {
      buf << name << " WOW" << delimeter
          << name << " stroke (ft)" << delimeter
          << name << " stroke velocity (ft/sec)" << delimeter
          << name << " compress force (lbs)" << delimeter;
    }
  }
 
  buf << " Total Gear Force_X (lbs)" << delimeter
      << " Total Gear Force_Y (lbs)" << delimeter
      << " Total Gear Force_Z (lbs)" << delimeter
      << " Total Gear Moment_L (ft-lbs)" << delimeter
      << " Total Gear Moment_M (ft-lbs)" << delimeter
      << " Total Gear Moment_N (ft-lbs)";
 
  return buf.str();
}

◆ GetGroundReactionValues()

string GetGroundReactionValues ( std::string delimeter ) const

Definition at line 198 of file FGGroundReactions.cpp.

{
  std::ostringstream buf;
 
  for (auto& gear: lGear) {
    if (gear->IsBogey()) {
      buf << (gear->GetWOW() ? "1" : "0") << delimeter
          << setprecision(5) << gear->GetCompLen() << delimeter
          << setprecision(6) << gear->GetCompVel() << delimeter
          << setprecision(10) << gear->GetCompForce() << delimeter
          << gear->GetWheelSideForce() << delimeter
          << gear->GetWheelRollForce() << delimeter
          << gear->GetBodyXForce() << delimeter
          << gear->GetBodyYForce() << delimeter
          << setprecision(6) << gear->GetWheelVel(eX) << delimeter
          << gear->GetWheelVel(eY) << delimeter
          << gear->GetWheelRollVel() << delimeter
          << gear->GetWheelSideVel() << delimeter
          << gear->GetWheelSlipAngle() << delimeter;
    } else {
      buf << (gear->GetWOW() ? "1" : "0") << delimeter
          << setprecision(5) << gear->GetCompLen() << delimeter
          << setprecision(6) << gear->GetCompVel() << delimeter
          << setprecision(10) << gear->GetCompForce() << delimeter;
    }
  }
 
  auto Accelerations = FDMExec->GetAccelerations();
 
  buf << Accelerations->GetGroundForces(eX) << delimeter
      << Accelerations->GetGroundForces(eY) << delimeter
      << Accelerations->GetGroundForces(eZ) << delimeter
      << Accelerations->GetGroundMoments(eX) << delimeter
      << Accelerations->GetGroundMoments(eY) << delimeter
      << Accelerations->GetGroundMoments(eZ);
 
  return buf.str();
}

◆ GetMoments() [1/2]

double GetMoments ( int idx ) const

inline

Definition at line 97 of file FGGroundReactions.h.

97{return vMoments(idx);}

◆ GetMoments() [2/2]

const FGColumnVector3 & GetMoments ( void ) const

inline

Definition at line 96 of file FGGroundReactions.h.

96{return vMoments;}

◆ GetMultipliersList()

std::vector< LagrangeMultiplier * > * GetMultipliersList ( void )

inline

Definition at line 120 of file FGGroundReactions.h.

120{ return &multipliers; }

◆ GetNumGearUnits()

int GetNumGearUnits ( void ) const

inline

Gets the number of gears.

Returns: the number of gears of the aircraft.

Definition at line 104 of file FGGroundReactions.h.

104{ return (int)lGear.size(); }

◆ GetWOW()

bool GetWOW ( void ) const

Definition at line 113 of file FGGroundReactions.cpp.

{
  for (auto& gear:lGear) {
    if (gear->IsBogey() && gear->GetWOW())
      return true;
  }
  return false;
}

◆ InitModel()

bool InitModel ( void )

overridevirtual

Reimplemented from FGModelFunctions.

Definition at line 66 of file FGGroundReactions.cpp.

{
  if (!FGModel::InitModel()) return false;
 
  vForces.InitMatrix();
  vMoments.InitMatrix();
  DsCmd = 0.0;
 
  multipliers.clear();
 
  for (auto& gear: lGear)
    gear->ResetToIC();
 
  return true;
}

◆ Load()

bool Load ( Element * el )

overridevirtual

Reimplemented from FGModel.

Definition at line 133 of file FGGroundReactions.cpp.

{
  int num=0;
 
  Name = "Ground Reactions Model: " + document->GetAttributeValue("name");
 
  Debug(2);
 
  // Perform base class Pre-Load
  if (!FGModel::Upload(document, true))
    return false;
 
  Element* contact_element = document->FindElement("contact");
  while (contact_element) {
    lGear.push_back(make_shared<FGLGear>(contact_element, FDMExec, num++, in));
    contact_element = document->FindNextElement("contact");
  }
 
  PostLoad(document, FDMExec);
 
  return true;
}

◆ RegisterLagrangeMultiplier()

void RegisterLagrangeMultiplier ( LagrangeMultiplier * lmult )

inline

Definition at line 119 of file FGGroundReactions.h.

119{ multipliers.push_back(lmult); }

◆ Run()

bool Run ( bool Holding )

overridevirtual

Runs the Ground Reactions model; called by the Executive 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: false if no error

Reimplemented from FGModel.

Definition at line 84 of file FGGroundReactions.cpp.

{
  if (FGModel::Run(Holding)) return true;
  if (Holding) return false;
 
  RunPreFunctions();
 
  vForces.InitMatrix();
  vMoments.InitMatrix();
 
  multipliers.clear();
 
  // Sum forces and moments for all gear, here.
  // Some optimizations may be made here - or rather in the gear code itself.
  // The gear ::Run() method is called several times - once for each gear.
  // Perhaps there is some commonality for things which only need to be
  // calculated once.
  for (auto& gear:lGear) {
    vForces  += gear->GetBodyForces();
    vMoments += gear->GetMoments();
  }
 
  RunPostFunctions();
 
  return false;
}

◆ SetDsCmd()

void SetDsCmd ( double cmd )

Sets the steering command.

Parameters

cmd	steering command in percent

Definition at line 124 of file FGGroundReactions.cpp.

{
  DsCmd = cmd;
  for (auto& gear:lGear)
    gear->SetSteerCmd(cmd);
}

Member Data Documentation

◆ in

FGLGear::Inputs in

Definition at line 122 of file FGGroundReactions.h.

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

Detailed Description

Configuration File Format of <ground_reactions> Section:

Public Member Functions

Public Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ FGGroundReactions()

Member Function Documentation

◆ GetDsCmd()

◆ GetForces() [1/2]

◆ GetForces() [2/2]

◆ GetGearUnit()

◆ GetGroundReactionStrings()

◆ GetGroundReactionValues()

◆ GetMoments() [1/2]

◆ GetMoments() [2/2]

◆ GetMultipliersList()

◆ GetNumGearUnits()

◆ GetWOW()

◆ InitModel()

◆ Load()

◆ RegisterLagrangeMultiplier()

◆ Run()

◆ SetDsCmd()

Member Data Documentation

◆ in