JSBSim Flight Dynamics Model
1.2.0 (05 Nov 2023)
An Open Source Flight Dynamics and Control Software Library in C++
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Encapsulates a filter for the flight control system.
The filter component can simulate any first or second order filter. The Tustin substitution is used to take filter definitions from LaPlace space to the time domain. The general format for a filter specification is:
The numerical integration of filters is made by a Runge-Kutta scheme of order 2 except for the second order filter which uses an RK scheme of order 3.
For a lag filter of the form \(\frac{C_1}{s+C_1}\), the corresponding filter definition is:
As an example, for the specific filter \(\frac{600}{s+600}\) the corresponding filter definition could be:
For a lead-lag filter of the form \(\frac{C_1s+C_2}{C_3s+C_4}\), the corresponding filter definition is:
For a washout filter of the form \(\frac{s}{s+C_1}\), the corresponding filter definition is:
For a second order filter of the form \(\frac{C_1s^2+C_2s+C_3}{C_4s^2+C_5s+C_6}\), the corresponding filter definition is:
For an integrator of the form \(\frac{C_1}{s}\), the corresponding filter definition is:
For the integrator, the trigger features the following behavior. If the trigger property value is:
By default, the integration scheme is the trapezoidal scheme.
An integrator is equivalent to a PID with the following parameters:
As a consequence, JSBSim internally uses PID controllers to simulate INTEGRATOR filters.
In all the filter specifications above, an <output> element is also seen. This is so that the last component in a "string" can copy its value to the appropriate output, such as the elevator, or speedbrake, etc.
Definition at line 215 of file FGFilter.h.
#include <FGFilter.h>
Public Member Functions | |
FGFilter (FGFCS *fcs, Element *element) | |
void | ResetPastStates (void) override |
bool | Run (void) override |
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 | 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. | |
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 const std::string & | GetVersion (void) |
Returns the version number of JSBSim. More... | |
static constexpr double | KelvinToFahrenheit (double kelvin) |
Converts from degrees Kelvin to degrees Fahrenheit. More... | |
static constexpr double | CelsiusToRankine (double celsius) |
Converts from degrees Celsius to degrees Rankine. More... | |
static constexpr double | RankineToCelsius (double rankine) |
Converts from degrees Rankine to degrees Celsius. More... | |
static constexpr double | KelvinToRankine (double kelvin) |
Converts from degrees Kelvin to degrees Rankine. More... | |
static constexpr double | RankineToKelvin (double rankine) |
Converts from degrees Rankine to degrees Kelvin. More... | |
static constexpr double | FahrenheitToCelsius (double fahrenheit) |
Converts from degrees Fahrenheit to degrees Celsius. More... | |
static constexpr double | CelsiusToFahrenheit (double celsius) |
Converts from degrees Celsius to degrees Fahrenheit. More... | |
static constexpr double | CelsiusToKelvin (double celsius) |
Converts from degrees Celsius to degrees Kelvin. More... | |
static constexpr double | KelvinToCelsius (double kelvin) |
Converts from degrees Kelvin to degrees Celsius. More... | |
static constexpr double | FeetToMeters (double measure) |
Converts from feet to meters. More... | |
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 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. More... | |
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__ |