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ardupilot/libraries/AP_Baro/AP_Baro.cpp

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/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* APM_Baro.cpp - barometer driver
*
*/
#include "AP_Baro.h"
#include <utility>
#include <AP_Common/AP_Common.h>
#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
#include <AP_BoardConfig/AP_BoardConfig.h>
#include <AP_BoardConfig/AP_BoardConfig_CAN.h>
#include <AP_Vehicle/AP_Vehicle_Type.h>
#include "AP_Baro_SITL.h"
#include "AP_Baro_BMP085.h"
#include "AP_Baro_BMP280.h"
#include "AP_Baro_HIL.h"
#include "AP_Baro_MS5611.h"
#include "AP_Baro_qflight.h"
#include "AP_Baro_QURT.h"
#if HAL_WITH_UAVCAN
#include "AP_Baro_UAVCAN.h"
#endif
#define C_TO_KELVIN 273.15f
// Gas Constant is from Aerodynamics for Engineering Students, Third Edition, E.L.Houghton and N.B.Carruthers
#define ISA_GAS_CONSTANT 287.26f
#define ISA_LAPSE_RATE 0.0065f
#define INTERNAL_TEMPERATURE_CLAMP 35.0f
extern const AP_HAL::HAL& hal;
// table of user settable parameters
const AP_Param::GroupInfo AP_Baro::var_info[] = {
// NOTE: Index numbers 0 and 1 were for the old integer
// ground temperature and pressure
// @Param: ABS_PRESS
// @DisplayName: Absolute Pressure
// @Description: calibrated ground pressure in Pascals
// @Units: Pa
// @Increment: 1
// @ReadOnly: True
// @Volatile: True
// @User: Advanced
AP_GROUPINFO("ABS_PRESS", 2, AP_Baro, sensors[0].ground_pressure, 0),
// @Param: TEMP
// @DisplayName: ground temperature
// @Description: calibrated ground temperature in degrees Celsius
// @Units: degC
// @Increment: 1
// @ReadOnly: True
// @Volatile: True
// @User: Advanced
AP_GROUPINFO("TEMP", 3, AP_Baro, _user_ground_temperature, 0),
// index 4 reserved for old AP_Int8 version in legacy FRAM
//AP_GROUPINFO("ALT_OFFSET", 4, AP_Baro, _alt_offset, 0),
// @Param: ALT_OFFSET
// @DisplayName: altitude offset
// @Description: altitude offset in meters added to barometric altitude. This is used to allow for automatic adjustment of the base barometric altitude by a ground station equipped with a barometer. The value is added to the barometric altitude read by the aircraft. It is automatically reset to 0 when the barometer is calibrated on each reboot or when a preflight calibration is performed.
// @Units: m
// @Increment: 0.1
// @User: Advanced
AP_GROUPINFO("ALT_OFFSET", 5, AP_Baro, _alt_offset, 0),
// @Param: PRIMARY
// @DisplayName: Primary barometer
// @Description: This selects which barometer will be the primary if multiple barometers are found
// @Values: 0:FirstBaro,1:2ndBaro,2:3rdBaro
// @User: Advanced
AP_GROUPINFO("PRIMARY", 6, AP_Baro, _primary_baro, 0),
// @Param: EXT_BUS
// @DisplayName: External baro bus
// @Description: This selects the bus number for looking for an I2C barometer
// @Values: -1:Disabled,0:Bus0,1:Bus1
// @User: Advanced
AP_GROUPINFO("EXT_BUS", 7, AP_Baro, _ext_bus, -1),
// @Param: SPEC_GRAV
// @DisplayName: Specific Gravity (For water depth measurement)
// @Description: This sets the specific gravity of the fluid when flying an underwater ROV.
// @Values: 1.0:Freshwater,1.024:Saltwater
AP_GROUPINFO_FRAME("SPEC_GRAV", 8, AP_Baro, _specific_gravity, 1.0, AP_PARAM_FRAME_SUB),
#if BARO_MAX_INSTANCES > 1
// @Param: ABS_PRESS2
// @DisplayName: Absolute Pressure
// @Description: calibrated ground pressure in Pascals
// @Units: Pa
// @Increment: 1
// @ReadOnly: True
// @Volatile: True
// @User: Advanced
AP_GROUPINFO("ABS_PRESS2", 9, AP_Baro, sensors[1].ground_pressure, 0),
// Slot 10 used to be TEMP2
#endif
#if BARO_MAX_INSTANCES > 2
// @Param: ABS_PRESS3
// @DisplayName: Absolute Pressure
// @Description: calibrated ground pressure in Pascals
// @Units: Pa
// @Increment: 1
// @ReadOnly: True
// @Volatile: True
// @User: Advanced
AP_GROUPINFO("ABS_PRESS3", 11, AP_Baro, sensors[2].ground_pressure, 0),
// Slot 12 used to be TEMP3
#endif
AP_GROUPEND
};
/*
AP_Baro constructor
*/
AP_Baro::AP_Baro()
{
AP_Param::setup_object_defaults(this, var_info);
}
// calibrate the barometer. This must be called at least once before
// the altitude() or climb_rate() interfaces can be used
void AP_Baro::calibrate(bool save)
{
// reset the altitude offset when we calibrate. The altitude
// offset is supposed to be for within a flight
_alt_offset.set_and_save(0);
// start by assuming all sensors are calibrated (for healthy() test)
for (uint8_t i=0; i<_num_sensors; i++) {
sensors[i].calibrated = true;
sensors[i].alt_ok = true;
}
// let the barometer settle for a full second after startup
// the MS5611 reads quite a long way off for the first second,
// leading to about 1m of error if we don't wait
for (uint8_t i = 0; i < 10; i++) {
uint32_t tstart = AP_HAL::millis();
do {
update();
if (AP_HAL::millis() - tstart > 500) {
AP_HAL::panic("PANIC: AP_Baro::read unsuccessful "
"for more than 500ms in AP_Baro::calibrate [2]\r\n");
}
hal.scheduler->delay(10);
} while (!healthy());
hal.scheduler->delay(100);
}
// now average over 5 values for the ground pressure and
// temperature settings
float sum_pressure[BARO_MAX_INSTANCES] = {0};
float sum_temperature[BARO_MAX_INSTANCES] = {0};
uint8_t count[BARO_MAX_INSTANCES] = {0};
const uint8_t num_samples = 5;
for (uint8_t c = 0; c < num_samples; c++) {
uint32_t tstart = AP_HAL::millis();
do {
update();
if (AP_HAL::millis() - tstart > 500) {
AP_HAL::panic("PANIC: AP_Baro::read unsuccessful "
"for more than 500ms in AP_Baro::calibrate [3]\r\n");
}
} while (!healthy());
for (uint8_t i=0; i<_num_sensors; i++) {
if (healthy(i)) {
sum_pressure[i] += sensors[i].pressure;
sum_temperature[i] += sensors[i].temperature;
count[i] += 1;
}
}
hal.scheduler->delay(100);
}
for (uint8_t i=0; i<_num_sensors; i++) {
if (count[i] == 0) {
sensors[i].calibrated = false;
} else {
if (save) {
sensors[i].ground_pressure.set_and_save(sum_pressure[i] / count[i]);
}
}
}
_guessed_ground_temperature = get_external_temperature();
// panic if all sensors are not calibrated
for (uint8_t i=0; i<_num_sensors; i++) {
if (sensors[i].calibrated) {
return;
}
}
AP_HAL::panic("AP_Baro: all sensors uncalibrated");
}
/*
update the barometer calibration
this updates the baro ground calibration to the current values. It
can be used before arming to keep the baro well calibrated
*/
void AP_Baro::update_calibration()
{
for (uint8_t i=0; i<_num_sensors; i++) {
if (healthy(i)) {
sensors[i].ground_pressure.set(get_pressure(i));
}
// don't notify the GCS too rapidly or we flood the link
uint32_t now = AP_HAL::millis();
if (now - _last_notify_ms > 10000) {
sensors[i].ground_pressure.notify();
_last_notify_ms = now;
}
}
// always update the guessed ground temp
_guessed_ground_temperature = get_external_temperature();
// force EAS2TAS to recalculate
_EAS2TAS = 0;
}
// return altitude difference in meters between current pressure and a
// given base_pressure in Pascal
float AP_Baro::get_altitude_difference(float base_pressure, float pressure) const
{
float ret;
float temp = get_ground_temperature() + C_TO_KELVIN;
float scaling = pressure / base_pressure;
// This is an exact calculation that is within +-2.5m of the standard
// atmosphere tables in the troposphere (up to 11,000 m amsl).
ret = 153.8462f * temp * (1.0f - expf(0.190259f * logf(scaling)));
return ret;
}
// return current scale factor that converts from equivalent to true airspeed
// valid for altitudes up to 10km AMSL
// assumes standard atmosphere lapse rate
float AP_Baro::get_EAS2TAS(void)
{
float altitude = get_altitude();
if ((fabsf(altitude - _last_altitude_EAS2TAS) < 25.0f) && !is_zero(_EAS2TAS)) {
// not enough change to require re-calculating
return _EAS2TAS;
}
// only estimate lapse rate for the difference from the ground location
// provides a more consistent reading then trying to estimate a complete
// ISA model atmosphere
float tempK = get_ground_temperature() + C_TO_KELVIN - ISA_LAPSE_RATE * altitude;
_EAS2TAS = safe_sqrt(1.225f / ((float)get_pressure() / (ISA_GAS_CONSTANT * tempK)));
_last_altitude_EAS2TAS = altitude;
return _EAS2TAS;
}
// return air density / sea level density - decreases as altitude climbs
float AP_Baro::get_air_density_ratio(void)
{
const float eas2tas = get_EAS2TAS();
if (eas2tas > 0.0f) {
return 1.0f/(sq(eas2tas));
} else {
return 1.0f;
}
}
// return current climb_rate estimate relative to time that calibrate()
// was called. Returns climb rate in meters/s, positive means up
// note that this relies on read() being called regularly to get new data
float AP_Baro::get_climb_rate(void)
{
if (_hil.have_alt) {
return _hil.climb_rate;
}
// we use a 7 point derivative filter on the climb rate. This seems
// to produce somewhat reasonable results on real hardware
return _climb_rate_filter.slope() * 1.0e3f;
}
// returns the ground temperature in degrees C, selecting either a user
// provided one, or the internal estimate
float AP_Baro::get_ground_temperature(void) const
{
if (is_zero(_user_ground_temperature)) {
return _guessed_ground_temperature;
} else {
return _user_ground_temperature;
}
}
/*
set external temperature to be used for calibration (degrees C)
*/
void AP_Baro::set_external_temperature(float temperature)
{
_external_temperature = temperature;
_last_external_temperature_ms = AP_HAL::millis();
}
/*
get the temperature in degrees C to be used for calibration purposes
*/
float AP_Baro::get_external_temperature(const uint8_t instance) const
{
// if we have a recent external temperature then use it
if (_last_external_temperature_ms != 0 && AP_HAL::millis() - _last_external_temperature_ms < 10000) {
return _external_temperature;
}
// if we don't have an external temperature then use the minimum
// of the barometer temperature and 35 degrees C. The reason for
// not just using the baro temperature is it tends to read high,
// often 30 degrees above the actual temperature. That means the
// EAS2TAS tends to be off by quite a large margin, as well as
// the calculation of altitude difference betweeen two pressures
// reporting a high temperature will cause the aircraft to
// estimate itself as flying higher then it actually is.
return MIN(get_temperature(instance), INTERNAL_TEMPERATURE_CLAMP);
}
bool AP_Baro::_add_backend(AP_Baro_Backend *backend)
{
if (!backend) {
return false;
}
if (_num_drivers >= BARO_MAX_DRIVERS) {
AP_HAL::panic("Too many barometer drivers");
}
drivers[_num_drivers++] = backend;
return true;
}
/*
macro to add a backend with check for too many sensors
We don't try to start more than the maximum allowed
*/
#define ADD_BACKEND(backend) \
do { _add_backend(backend); \
if (_num_drivers == BARO_MAX_DRIVERS || \
_num_sensors == BARO_MAX_INSTANCES) { \
return; \
} \
} while (0)
/*
initialise the barometer object, loading backend drivers
*/
void AP_Baro::init(void)
{
// ensure that there isn't a previous ground temperature saved
if (!is_zero(_user_ground_temperature)) {
_user_ground_temperature.set_and_save(0.0f);
_user_ground_temperature.notify();
}
if (_hil_mode) {
drivers[0] = new AP_Baro_HIL(*this);
_num_drivers = 1;
return;
}
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
ADD_BACKEND(new AP_Baro_SITL(*this));
return;
#endif
#if HAL_WITH_UAVCAN
bool added;
do {
added = _add_backend(AP_Baro_UAVCAN::probe(*this));
if (_num_drivers == BARO_MAX_DRIVERS || _num_sensors == BARO_MAX_INSTANCES) {
return;
}
} while (added);
#endif
#if HAL_BARO_DEFAULT == HAL_BARO_PX4 || HAL_BARO_DEFAULT == HAL_BARO_VRBRAIN
switch (AP_BoardConfig::get_board_type()) {
case AP_BoardConfig::PX4_BOARD_PX4V1:
#ifdef HAL_BARO_MS5611_I2C_BUS
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.i2c_mgr->get_device(HAL_BARO_MS5611_I2C_BUS, HAL_BARO_MS5611_I2C_ADDR))));
#endif
break;
case AP_BoardConfig::PX4_BOARD_PIXHAWK:
case AP_BoardConfig::PX4_BOARD_PHMINI:
case AP_BoardConfig::PX4_BOARD_AUAV21:
case AP_BoardConfig::PX4_BOARD_PH2SLIM:
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.spi->get_device(HAL_BARO_MS5611_NAME))));
break;
case AP_BoardConfig::PX4_BOARD_PIXHAWK2:
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.spi->get_device(HAL_BARO_MS5611_SPI_EXT_NAME))));
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.spi->get_device(HAL_BARO_MS5611_NAME))));
break;
case AP_BoardConfig::PX4_BOARD_PIXRACER:
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.spi->get_device(HAL_BARO_MS5611_SPI_INT_NAME))));
break;
case AP_BoardConfig::PX4_BOARD_AEROFC:
#ifdef HAL_BARO_MS5607_I2C_BUS
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.i2c_mgr->get_device(HAL_BARO_MS5607_I2C_BUS, HAL_BARO_MS5607_I2C_ADDR)),
AP_Baro_MS56XX::BARO_MS5607));
#endif
break;
default:
break;
}
#elif HAL_BARO_DEFAULT == HAL_BARO_HIL
drivers[0] = new AP_Baro_HIL(*this);
_num_drivers = 1;
#elif HAL_BARO_DEFAULT == HAL_BARO_BMP085
drivers[0] = new AP_Baro_BMP085(*this,
std::move(hal.i2c_mgr->get_device(HAL_BARO_BMP085_BUS, HAL_BARO_BMP085_I2C_ADDR)));
_num_drivers = 1;
#elif HAL_BARO_DEFAULT == HAL_BARO_BMP280_I2C
ADD_BACKEND(AP_Baro_BMP280::probe(*this,
std::move(hal.i2c_mgr->get_device(HAL_BARO_BMP280_BUS, HAL_BARO_BMP280_I2C_ADDR))));
#elif HAL_BARO_DEFAULT == HAL_BARO_BMP280_SPI
ADD_BACKEND(AP_Baro_BMP280::probe(*this,
std::move(hal.spi->get_device(HAL_BARO_BMP280_NAME))));
#elif HAL_BARO_DEFAULT == HAL_BARO_MS5611_I2C
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.i2c_mgr->get_device(HAL_BARO_MS5611_I2C_BUS, HAL_BARO_MS5611_I2C_ADDR))));
#elif HAL_BARO_DEFAULT == HAL_BARO_MS5611_SPI
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.spi->get_device(HAL_BARO_MS5611_NAME))));
#elif HAL_BARO_DEFAULT == HAL_BARO_MS5607_I2C
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.i2c_mgr->get_device(HAL_BARO_MS5607_I2C_BUS, HAL_BARO_MS5607_I2C_ADDR)),
AP_Baro_MS56XX::BARO_MS5607));
#elif HAL_BARO_DEFAULT == HAL_BARO_MS5637_I2C
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.i2c_mgr->get_device(HAL_BARO_MS5637_I2C_BUS, HAL_BARO_MS5637_I2C_ADDR)),
AP_Baro_MS56XX::BARO_MS5637));
#elif HAL_BARO_DEFAULT == HAL_BARO_QFLIGHT
drivers[0] = new AP_Baro_QFLIGHT(*this);
_num_drivers = 1;
#elif HAL_BARO_DEFAULT == HAL_BARO_QURT
drivers[0] = new AP_Baro_QURT(*this);
_num_drivers = 1;
#endif
// can optionally have baro on I2C too
if (_ext_bus >= 0) {
#if APM_BUILD_TYPE(APM_BUILD_ArduSub)
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.i2c_mgr->get_device(_ext_bus, HAL_BARO_MS5837_I2C_ADDR)), AP_Baro_MS56XX::BARO_MS5837));
#else
ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
std::move(hal.i2c_mgr->get_device(_ext_bus, HAL_BARO_MS5611_I2C_ADDR))));
#endif
}
if (_num_drivers == 0 || _num_sensors == 0 || drivers[0] == nullptr) {
AP_BoardConfig::sensor_config_error("Baro: unable to initialise driver");
}
}
/*
call update on all drivers
*/
void AP_Baro::update(void)
{
if (fabsf(_alt_offset - _alt_offset_active) > 0.01f) {
// If there's more than 1cm difference then slowly slew to it via LPF.
// The EKF does not like step inputs so this keeps it happy.
_alt_offset_active = (0.95f*_alt_offset_active) + (0.05f*_alt_offset);
} else {
_alt_offset_active = _alt_offset;
}
if (!_hil_mode) {
for (uint8_t i=0; i<_num_drivers; i++) {
drivers[i]->backend_update(i);
}
}
for (uint8_t i=0; i<_num_sensors; i++) {
if (sensors[i].healthy) {
// update altitude calculation
float ground_pressure = sensors[i].ground_pressure;
if (is_zero(ground_pressure) || isnan(ground_pressure) || isinf(ground_pressure)) {
sensors[i].ground_pressure = sensors[i].pressure;
}
float altitude = sensors[i].altitude;
if (sensors[i].type == BARO_TYPE_AIR) {
float pressure = sensors[i].pressure + sensors[i].p_correction;
altitude = get_altitude_difference(sensors[i].ground_pressure, pressure);
} else if (sensors[i].type == BARO_TYPE_WATER) {
//101325Pa is sea level air pressure, 9800 Pascal/ m depth in water.
//No temperature or depth compensation for density of water.
altitude = (sensors[i].ground_pressure - sensors[i].pressure) / 9800.0f / _specific_gravity;
}
// sanity check altitude
sensors[i].alt_ok = !(isnan(altitude) || isinf(altitude));
if (sensors[i].alt_ok) {
sensors[i].altitude = altitude + _alt_offset_active;
}
}
if (_hil.have_alt) {
sensors[0].altitude = _hil.altitude;
}
if (_hil.have_last_update) {
sensors[0].last_update_ms = _hil.last_update_ms;
}
}
// ensure the climb rate filter is updated
if (healthy()) {
_climb_rate_filter.update(get_altitude(), get_last_update());
}
// choose primary sensor
if (_primary_baro >= 0 && _primary_baro < _num_sensors && healthy(_primary_baro)) {
_primary = _primary_baro;
} else {
_primary = 0;
for (uint8_t i=0; i<_num_sensors; i++) {
if (healthy(i)) {
_primary = i;
break;
}
}
}
}
/*
call accumulate on all drivers
*/
void AP_Baro::accumulate(void)
{
for (uint8_t i=0; i<_num_drivers; i++) {
drivers[i]->accumulate();
}
}
/* register a new sensor, claiming a sensor slot. If we are out of
slots it will panic
*/
uint8_t AP_Baro::register_sensor(void)
{
if (_num_sensors >= BARO_MAX_INSTANCES) {
AP_HAL::panic("Too many barometers");
}
return _num_sensors++;
}
/*
check if all barometers are healthy
*/
bool AP_Baro::all_healthy(void) const
{
for (uint8_t i=0; i<_num_sensors; i++) {
if (!healthy(i)) {
return false;
}
}
return _num_sensors > 0;
}
// set a pressure correction from AP_TempCalibration
void AP_Baro::set_pressure_correction(uint8_t instance, float p_correction)
{
if (instance < _num_sensors) {
sensors[instance].p_correction = p_correction;
}
}
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