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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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JSBSim Flight Dynamics Model
1.2.0 (05 Nov 2023)
An Open Source Flight Dynamics and Control Software Library in C++
|
Encapsulates a gain component for the flight control system.
The gain component merely multiplies the input by a gain. The pure gain form of the component specification is:
Example:
Note: the input property name may be immediately preceded by a minus sign to invert that signal.
The scheduled gain component multiplies the input by a variable gain that is dependent on another property (such as qbar, altitude, etc.). The lookup mapping is in the form of a table. This kind of component might be used, for example, in a case where aerosurface deflection must only be commanded to acceptable settings - i.e at higher qbar the commanded elevator setting might be attenuated. The form of the scheduled gain component specification is:
Example:
An overall GAIN may be supplied that is multiplicative with the scheduled gain.
Note: the input property name may be immediately preceded by a minus sign to invert that signal.
In the example above, we see the utility of the overall gain value in effecting a degrees-to-radians conversion.
The aerosurface scale component is a modified version of the simple gain component. The purpose for this component is to take control inputs from the domain minimum and maximum, as specified (or from -1 to +1 by default) and scale them to map to a specified range. This can be done, for instance, to match the component outputs to the expected inputs to a flight control system.
The zero_centered element dictates whether the domain-to-range mapping is linear or centered about zero. For example, if zero_centered is false, and if the domain or range is not symmetric about zero, and an input value is zero, the output will not be zero. Let's say that the domain is min=-2 and max=+4, with a range of -1 to +1. If the input is 0.0, then the "normalized" input is calculated to be 33% of the way from the minimum to the maximum. That input would be mapped to an output of -0.33, which is 33% of the way from the range minimum to maximum. If zero_centered is set to true (or 1) then an input of 0.0 will be mapped to an output of 0.0, although if either the domain or range are unsymmetric about 0.0, then the scales for the positive and negative portions of the input domain (above and below 0.0) will be different. The zero_centered element is true by default. Note that this feature may be important for some control surface mappings, where the maximum upper and lower deflections may be different, but where a zero setting is desired to be the "undeflected" value, and where full travel of the stick is desired to cause a full deflection of the control surface.
The form of the aerosurface scaling component specification is:
Note: the input property name may be immediately preceded by a minus sign to invert that signal.
For instance, the normal and expected ability of a pilot to push or pull on a control stick is about 50 pounds. The input to the pitch channel block diagram of a flight control system is often in units of pounds. Yet, the joystick control input usually defines a span from -1 to +1. The aerosurface_scale form of the gain component maps the inputs to the desired output range. The example below shoes a simple aerosurface_scale component that maps the joystick input to a range of +/- 50, which represents pilot stick force in pounds for the F-16.
#include <FGGain.h>
Inheritance diagram for FGGain: Collaboration diagram for FGGain:Public Member Functions | |
| FGGain (FGFCS *fcs, Element *element) | |
| 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 | 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. | |
| 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__ |
1.9.1 
