air_data.h File Reference

Air Data interface. More...

#include "std.h"
#include "pprzlink/pprzlink_device.h"
#include "pprzlink/pprzlink_transport.h"

Include dependency graph for air_data.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	AirData
	Air Data strucute. More...

Functions
void	air_data_init (void)
	AirData initialization.
void	air_data_periodic (void)
	Check health.
void	air_data_parse_WIND_INFO (struct link_device *dev, struct transport_tx *trans, uint8_t *buf)
	Parse datalink wind info message.
float	air_data_get_amsl (void)
	Return AMSL (altitude AboveSeaLevel).
float	eas_from_dynamic_pressure (float q)
	Calculate equivalent airspeed from dynamic pressure.
float	get_tas_factor (float p, float t)
	Calculate true airspeed (TAS) factor.
float	tas_from_eas (float eas)
	Calculate true airspeed from equivalent airspeed.
float	eas_from_tas (float tas)
	Calculate equivalent airspeed from true airspeed.
float	tas_from_dynamic_pressure (float q)
	Calculate true airspeed from dynamic pressure.

Variables
struct AirData	air_data
	global AirData state

Detailed Description

Air Data interface.

• pressures
• airspeed
• angle of attack and sideslip
• wind

Definition in file air_data.h.

---

Data Structure Documentation

AirData

struct AirData

Air Data strucute.

Definition at line 39 of file air_data.h.

Data Fields
float	airspeed	Equivalent Air Speed (equals to Calibrated Air Speed at low speed/altitude) (in m/s, -1 if unknown.
float	amsl_baro	altitude above sea level in m from pressure and QNH
bool	amsl_baro_valid	TRUE if amsl_baro is currently valid.
float	aoa	angle of attack (rad)
bool	calc_airspeed	if TRUE, calculate airspeed from differential pressure
bool	calc_amsl_baro	if TRUE, calculate amsl_baro
bool	calc_qnh_once	flag to calculate QNH with next pressure measurement
bool	calc_tas_factor	if TRUE, calculate tas_factor when getting a temp measurement
float	differential	Differential pressure (total - static pressure) (Pa)
float	pressure	Static atmospheric pressure (Pa), -1 if unknown.
float	qnh	Barometric pressure adjusted to sea level in hPa, -1 if unknown.
float	sideslip	sideslip angle (rad)
float	tas	True Air Speed (TAS) in m/s, -1 if unknown.
float	tas_factor	factor to convert equivalent airspeed (EAS) to true airspeed (TAS)
float	temperature	temperature in degrees Celcius, -1000 if unknown
float	wind_dir	wind direction (rad, 0 north, >0 clockwise)
float	wind_speed	wind speed (m/s)

Function Documentation

air_data_get_amsl()

float air_data_get_amsl ( void  )

extern

Return AMSL (altitude AboveSeaLevel).

If AMSL from baro is valid, return that, otherwise from gps.

Definition at line 259 of file air_data.c.

References air_data, LlaCoor_f::alt, AirData::amsl_baro, AirData::amsl_baro_valid, and stateGetPositionLla_f().

Referenced by compute_tas_factor().

Here is the call graph for this function:

Here is the caller graph for this function:

air_data_init()

void air_data_init ( void  )

extern

AirData initialization.

Called at startup.

Called at startup. Bind ABI messages

Definition at line 218 of file air_data.c.

References air_data, AIR_DATA_AIRSPEED_ID, AIR_DATA_BARO_ABS_ID, AIR_DATA_BARO_DIFF_ID, AIR_DATA_CALC_AIRSPEED, AIR_DATA_CALC_AMSL_BARO, AIR_DATA_CALC_TAS_FACTOR, AIR_DATA_INCIDENCE_ID, AIR_DATA_TAS_FACTOR, AIR_DATA_TEMPERATURE_ID, AirData::airspeed, airspeed_cb(), airspeed_ev, AirData::amsl_baro, AirData::amsl_baro_valid, AirData::aoa, baro_health_counter, AirData::calc_airspeed, AirData::calc_amsl_baro, AirData::calc_qnh_once, AirData::calc_tas_factor, DefaultPeriodic, AirData::differential, foo, incidence_cb(), incidence_ev, AirData::pressure, pressure_abs_cb(), pressure_abs_ev, pressure_diff_cb(), pressure_diff_ev, AirData::qnh, register_periodic_telemetry(), send_air_data(), send_amsl(), send_baro_raw(), AirData::sideslip, AirData::tas, AirData::tas_factor, AirData::temperature, temperature_cb(), temperature_ev, AirData::wind_dir, and AirData::wind_speed.

Here is the call graph for this function:

air_data_parse_WIND_INFO()

void air_data_parse_WIND_INFO ( struct link_device *  dev, struct transport_tx *  trans, uint8_t *  buf  )

extern

Parse datalink wind info message.

Definition at line 279 of file air_data.c.

References air_data, AirData::airspeed, dev, eas_from_tas(), float_vect2_norm(), foo, stateGetAirspeed_f(), stateSetAirspeed_f(), stateSetHorizontalWindspeed_f(), stateSetVerticalWindspeed_f(), AirData::tas, AirData::wind_dir, AirData::wind_speed, FloatVect2::x, and FloatVect2::y.

Here is the call graph for this function:

air_data_periodic()

void air_data_periodic ( void  )

extern

Check health.

Needs to be called periodically.

Definition at line 269 of file air_data.c.

References air_data, AirData::amsl_baro_valid, and baro_health_counter.

eas_from_dynamic_pressure()

float eas_from_dynamic_pressure ( float  q )

extern

Calculate equivalent airspeed from dynamic pressure.

Dynamic pressure (also called impact pressure) is the difference between total(pitot) and static pressure.

Parameters

q	dynamic pressure in Pa

Returns

equivalent airspeed in m/s

Dynamic pressure (also called impact pressure) is the difference between total(pitot) and static pressure.

Airspeed from dynamic pressure:

with as air density. Using standard sea level air density gives you equivalent airspeed (EAS).

Parameters

q	dynamic pressure in Pa

Returns

equivalent airspeed in m/s

Definition at line 322 of file air_data.c.

References foo, PPRZ_ISA_AIR_DENSITY, and sign().

Referenced by pressure_diff_cb(), and tas_from_dynamic_pressure().

Here is the call graph for this function:

Here is the caller graph for this function:

eas_from_tas()

float eas_from_tas ( float  tas )

extern

Calculate equivalent airspeed from true airspeed.

Parameters

tas	true airspeed (TAS) in m/s

Returns

equivalent airspeed in m/s

EAS from True airspeed (TAS): EAS = TAS / air_data.tas_factor

Parameters

tas	true airspeed (TAS) in m/s

Returns

equivalent airspeed in m/s

Definition at line 410 of file air_data.c.

References air_data, compute_tas_factor(), and AirData::tas_factor.

Referenced by air_data_parse_WIND_INFO(), and wind_estimation_quadrotor_periodic().

Here is the call graph for this function:

Here is the caller graph for this function:

get_tas_factor()

float get_tas_factor ( float  p, float  t  )

extern

Calculate true airspeed (TAS) factor.

TAS = tas_factor * EAS

Parameters

p	current air pressure in Pa
t	current air temperature in degrees Celcius

Returns

tas factor

TAS = tas_factor * EAS

True airspeed (TAS) from equivalent airspeed (EAS):

and where

• is the air pressure at the flight condition
• is the air pressure at sea level = 101325 Pa
• is the air temperature at the flight condition
• is the air temperature at sea level = 288.15 K

Parameters

p	current air pressure in Pa
t	current air temperature in degrees Celcius

Returns

tas factor

Definition at line 355 of file air_data.c.

References foo, KelvinOfCelsius, p, PPRZ_ISA_SEA_LEVEL_PRESSURE, and PPRZ_ISA_SEA_LEVEL_TEMP.

Referenced by compute_tas_factor(), and temperature_cb().

Here is the caller graph for this function:

tas_from_dynamic_pressure()

float tas_from_dynamic_pressure ( float  q )

extern

Calculate true airspeed from dynamic pressure.

Dynamic pressure (also called impact pressure) is the difference between total(pitot) and static pressure.

Parameters

q	dynamic pressure in Pa

Returns

true airspeed in m/s

Definition at line 424 of file air_data.c.

References eas_from_dynamic_pressure(), and tas_from_eas().

Referenced by pressure_diff_cb().

Here is the call graph for this function:

Here is the caller graph for this function:

tas_from_eas()

float tas_from_eas ( float  eas )

extern

Calculate true airspeed from equivalent airspeed.

Parameters

eas	equivalent airspeed (EAS) in m/s

Returns

true airspeed in m/s

True airspeed (TAS) from EAS: TAS = air_data.tas_factor * EAS

Parameters

eas	equivalent airspeed (EAS) in m/s

Returns

true airspeed in m/s

Definition at line 395 of file air_data.c.

References air_data, compute_tas_factor(), foo, and AirData::tas_factor.

Referenced by airspeed_cb(), airspeed_cb(), pressure_diff_cb(), and tas_from_dynamic_pressure().

Here is the call graph for this function:

Here is the caller graph for this function:

Variable Documentation

air_data

struct AirData air_data

extern

global AirData state

Definition at line 41 of file air_data.c.

Referenced by air_data_get_amsl(), air_data_init(), air_data_parse_WIND_INFO(), air_data_periodic(), airspeed_cb(), compute_tas_factor(), eas_from_tas(), incidence_cb(), pressure_abs_cb(), pressure_diff_cb(), save_speeds(), send_air_data(), send_amsl(), send_baro_raw(), send_windtunnel_meas(), tas_from_eas(), and temperature_cb().