FGSwitch Class Reference

Detailed Description

Encapsulates a switch for the flight control system.

The switch component models a switch - either on/off or a multi-choice rotary switch. The switch can represent a physical cockpit switch, or can represent a logical switch, where several conditions might need to be satisfied before a particular state is reached. The value of the switch - the output value for the component - is chosen depending on the state of the switch. Each switch is comprised of one or more tests. Each test has a value associated with it. The first test that evaluates to true will set the output value of the switch according to the value parameter belonging to that test. Each test contains one or more conditions, which each must be logically related (if there are more than one) given the value of the logic attribute, and which takes the form:

property conditional property|value

e.g.

qbar ge 21.0

or,

roll_rate == pitch_rate

Within a test, additional tests can be specified, which allows for complex groupings of logical comparisons. Each test contains additional conditions, as well as possibly additional tests.

<switch name="switch1">
  <default value="{property|value}"/>
  <test logic="{AND|OR}" value="{property|value}">
    {property} {conditional} {property|value}
    <test logic="{AND|OR}">
      {property} {conditional} {property|value}
      ...
    </test>
    ...
  </test>
  <test logic="{AND|OR}" value="{property|value}">
    {property} {conditional} {property|value}
    ...
  </test>
  ...
  [<output> {property} </output>]
</switch>

Here's an example:

<switch name="roll a/p autoswitch">
  <default value="0.0"/>
  <test value="fcs/roll-ap-error-summer">
    ap/attitude_hold == 1
  </test>
</switch>

Note: In the "logic" attribute, "AND" is the default logic, if none is supplied.

The above example specifies that the default value of the component (i.e. the output property of the component, addressed by the property, ap/roll-ap-autoswitch) is 0.0.

If or when the attitude hold switch is selected (property ap/attitude_hold takes the value 1), the value of the switch component will be whatever value fcs/roll-ap-error-summer is.

Author

Jon S. Berndt

Definition at line 130 of file FGSwitch.h.

#include <FGSwitch.h>

Inheritance diagram for FGSwitch:

Collaboration diagram for FGSwitch:

Public Member Functions
	FGSwitch (FGFCS *fcs, Element *element)
	Constructor.
	~FGSwitch ()
	Destructor.
bool	Run (void) override
	Executes the switch logic.
Public Member Functions inherited from FGFCSComponent
	FGFCSComponent (FGFCS *fcs, Element *el)
	Constructor.
virtual	~FGFCSComponent ()
	Destructor.
std::string	GetName (void) const
double	GetOutput (void) const
virtual double	GetOutputPct (void) const
std::string	GetType (void) const
virtual void	ResetPastStates (void)
virtual void	SetOutput (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.

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 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 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 Public Attributes inherited from 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 FGFCSComponent
virtual void	bind (Element *el, FGPropertyManager *pm)
void	CheckInputNodes (size_t MinNodes, size_t MaxNodes, Element *el)
void	Clip (void)
void	Delay (void)
Static Protected Member Functions inherited from FGJSBBase
static std::string	CreateIndexedPropertyName (const std::string &Property, int index)
Protected Attributes inherited from FGFCSComponent
bool	clip
FGParameter_ptr	ClipMax
FGParameter_ptr	ClipMin
bool	cyclic_clip
unsigned int	delay
double	delay_time
double	dt
FGFCS *	fcs
int	index
std::vector< FGPropertyValue_ptr >	InitNodes
double	Input
std::vector< FGPropertyValue_ptr >	InputNodes
std::string	Name
double	Output
std::vector< double >	output_array
std::vector< FGPropertyNode_ptr >	OutputNodes
std::string	Type
Static Protected Attributes inherited from FGJSBBase
static constexpr double	radtodeg = 180. / M_PI
static constexpr double	degtorad = M_PI / 180.
static constexpr double	hptoftlbssec = 550.0
static constexpr double	psftoinhg = 0.014138
static constexpr double	psftopa = 47.88
static constexpr double	fttom = 0.3048
static constexpr double	ktstofps = 1852./(3600*fttom)
static constexpr double	fpstokts = 1.0 / ktstofps
static constexpr double	inchtoft = 1.0/12.0
static constexpr double	m3toft3 = 1.0/(fttom*fttom*fttom)
static constexpr double	in3tom3 = inchtoft*inchtoft*inchtoft/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__

Constructor & Destructor Documentation

FGSwitch()

FGSwitch	(	FGFCS *	fcs,
		Element *	element
	)

Constructor.

Parameters

fcs	a pointer to the parent FGFCS class
element	a pointer to the Element (from the config file XML tree) that represents this switch component

Definition at line 77 of file FGSwitch.cpp.

                                               : FGFCSComponent(fcs, element)
{
  string value;
  Test *current_test;
  auto PropertyManager = fcs->GetPropertyManager();
 
  bind(element, PropertyManager.get()); // Bind() this component here in case it is used in its own
                                        // definition for a sample-and-hold
  Element* test_element = element->FindElement("default");
  if (test_element) {
    current_test = new Test;
    value = test_element->GetAttributeValue("value");
    current_test->setTestValue(value, Name, PropertyManager, test_element);
    current_test->Default = true;
    auto output_value = current_test->OutputValue.ptr();
    if (delay > 0 && dynamic_cast<FGRealValue*>(output_value)) { // If there is a delay
      double v = output_value->GetValue();
      for (unsigned int i=0; i<delay-1; i++) {  // Initialize the delay buffer to the default value
        output_array[i] = v;                    // for the switch if that value is a number.
      }
    }
    tests.push_back(current_test);
  }
 
  test_element = element->FindElement("test");
  while (test_element) {
    current_test = new Test;
    current_test->condition = new FGCondition(test_element, PropertyManager);
    value = test_element->GetAttributeValue("value");
    current_test->setTestValue(value, Name, PropertyManager, test_element);
    tests.push_back(current_test);
    test_element = element->FindNextElement("test");
  }
 
  Debug(0);
}

Here is the call graph for this function:

~FGSwitch()

~FGSwitch

(

)

Destructor.

Definition at line 116 of file FGSwitch.cpp.

{
  for (auto test: tests) {
    delete test->condition;
    delete test;
  }
 
  Debug(1);
}

Member Function Documentation

Run()

bool Run ( void  )

overridevirtual

Executes the switch logic.

Returns

true - always

Reimplemented from FGFCSComponent.

Definition at line 128 of file FGSwitch.cpp.

{
  bool pass = false;
  double default_output=0.0;
 
  // To detect errors early, make sure all conditions and values can be
  // evaluated in the first time step.
  if (!initialized) {
    initialized = true;
    VerifyProperties();
  }
 
  for (auto test: tests) {
    if (test->Default) {
      default_output = test->OutputValue->GetValue();
    } else {
      pass = test->condition->Evaluate();
    }
 
    if (pass) {
      Output = test->OutputValue->GetValue();
      break;
    }
  }
 
  if (!pass) Output = default_output;
 
  if (delay != 0) Delay();
  Clip();
  SetOutput();
 
  return true;
}

---

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

• FGSwitch.h
• FGSwitch.cpp