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ardupilot/libraries/AP_Baro/AP_Baro.cpp

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
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_Math/AP_Math.h>
#include <AP_Common/AP_Common.h>
#include "AP_Baro.h"
#include <AP_HAL/AP_HAL.h>
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: pascals
// @Increment: 1
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: degrees celsius
// @Increment: 1
AP_GROUPINFO("TEMP", 3, AP_Baro, sensors[0].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: meters
// @Increment: 0.1
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
AP_GROUPINFO("PRIMARY", 6, AP_Baro, _primary_baro, 0),
AP_GROUPEND
};
/*
AP_Baro constructor
*/
AP_Baro::AP_Baro() :
_num_drivers(0),
_num_sensors(0),
_primary(0),
_last_altitude_EAS2TAS(0.0f),
_EAS2TAS(0.0f),
_external_temperature(0.0f),
_last_external_temperature_ms(0),
_hil_mode(false)
{
memset(sensors, 0, sizeof(sensors));
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()
{
// 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 = hal.scheduler->millis();
do {
update();
if (hal.scheduler->millis() - tstart > 500) {
hal.scheduler->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 = hal.scheduler->millis();
do {
update();
if (hal.scheduler->millis() - tstart > 500) {
hal.scheduler->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 {
sensors[i].ground_pressure.set_and_save(sum_pressure[i] / count[i]);
sensors[i].ground_temperature.set_and_save(sum_temperature[i] / count[i]);
}
}
// panic if all sensors are not calibrated
for (uint8_t i=0; i<_num_sensors; i++) {
if (sensors[i].calibrated) {
return;
}
}
hal.scheduler->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_and_notify(get_pressure(i));
}
float last_temperature = sensors[i].ground_temperature;
sensors[i].ground_temperature.set_and_notify(get_calibration_temperature(i));
if (fabsf(last_temperature - sensors[i].ground_temperature) > 3) {
// reset _EAS2TAS to force it to recalculate. This happens
// when a digital airspeed sensor comes online
_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() + 273.15f;
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) < 100.0f) && !is_zero(_EAS2TAS)) {
// not enough change to require re-calculating
return _EAS2TAS;
}
float tempK = get_calibration_temperature() + 273.15f - 0.0065f * altitude;
_EAS2TAS = safe_sqrt(1.225f / ((float)get_pressure() / (287.26f * 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)
{
float eas2tas = get_EAS2TAS();
if (eas2tas > 0.0f) {
return 1.0f/(sq(get_EAS2TAS()));
} else {
return 1.0f;
}
}
// return current climb_rate estimeate 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)
{
// 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;
}
/*
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 = hal.scheduler->millis();
}
/*
get the temperature in degrees C to be used for calibration purposes
*/
float AP_Baro::get_calibration_temperature(uint8_t instance) const
{
// if we have a recent external temperature then use it
if (_last_external_temperature_ms != 0 && hal.scheduler->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 25 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
float ret = get_temperature(instance);
if (ret > 25) {
ret = 25;
}
return ret;
}
/*
initialise the barometer object, loading backend drivers
*/
void AP_Baro::init(void)
{
if (_hil_mode) {
drivers[0] = new AP_Baro_HIL(*this);
_num_drivers = 1;
return;
}
#if HAL_BARO_DEFAULT == HAL_BARO_PX4 || HAL_BARO_DEFAULT == HAL_BARO_VRBRAIN
drivers[0] = new AP_Baro_PX4(*this);
_num_drivers = 1;
#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);
_num_drivers = 1;
}
#elif HAL_BARO_DEFAULT == HAL_BARO_MS5611 && HAL_BARO_MS5611_I2C_BUS == 0
{
drivers[0] = new AP_Baro_MS5611(*this, new AP_SerialBus_I2C(hal.i2c, HAL_BARO_MS5611_I2C_ADDR), false);
_num_drivers = 1;
}
#elif HAL_BARO_DEFAULT == HAL_BARO_MS5611 && HAL_BARO_MS5611_I2C_BUS == 1
{
drivers[0] = new AP_Baro_MS5611(*this, new AP_SerialBus_I2C(hal.i2c1, HAL_BARO_MS5611_I2C_ADDR), false);
_num_drivers = 1;
}
#elif HAL_BARO_DEFAULT == HAL_BARO_MS5611_SPI
{
drivers[0] = new AP_Baro_MS5611(*this,
new AP_SerialBus_SPI(AP_HAL::SPIDevice_MS5611,
AP_HAL::SPIDeviceDriver::SPI_SPEED_HIGH),
true);
_num_drivers = 1;
}
#elif HAL_BARO_DEFAULT == HAL_BARO_MS5607 && HAL_BARO_MS5607_I2C_BUS == 1
{
drivers[0] = new AP_Baro_MS5607(*this, new AP_SerialBus_I2C(hal.i2c1, HAL_BARO_MS5607_I2C_ADDR), true);
_num_drivers = 1;
}
#elif HAL_BARO_DEFAULT == HAL_BARO_MS5637_I2C
{
AP_SerialBus *bus = new AP_SerialBus_I2C(HAL_BARO_MS5611_I2C_POINTER,
HAL_BARO_MS5611_I2C_ADDR);
drivers[0] = new AP_Baro_MS5637(*this, bus, true);
_num_drivers = 1;
}
#endif
if (_num_drivers == 0 || _num_sensors == 0 || drivers[0] == NULL) {
hal.scheduler->panic("Baro: unable to initialise driver");
}
}
/*
call update on all drivers
*/
void AP_Baro::update(void)
{
if (!_hil_mode) {
for (uint8_t i=0; i<_num_drivers; i++) {
drivers[i]->update();
}
}
// consider a sensor as healthy if it has had an update in the
// last 0.5 seconds
uint32_t now = hal.scheduler->millis();
for (uint8_t i=0; i<_num_sensors; i++) {
sensors[i].healthy = (now - sensors[i].last_update_ms < 500) && !is_zero(sensors[i].pressure);
}
for (uint8_t i=0; i<_num_sensors; i++) {
if (sensors[i].healthy) {
// update altitude calculation
if (is_zero(sensors[i].ground_pressure)) {
sensors[i].ground_pressure = sensors[i].pressure;
}
float altitude = get_altitude_difference(sensors[i].ground_pressure, sensors[i].pressure);
// sanity check altitude
sensors[i].alt_ok = !(isnan(altitude) || isinf(altitude));
if (sensors[i].alt_ok) {
sensors[i].altitude = altitude + _alt_offset;
}
}
}
// 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) {
hal.scheduler->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;
}
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