airspeed_selector_main.cpp

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#include <drivers/drv_hrt.h>
#include <ecl/airdata/WindEstimator.hpp>
#include <matrix/math.hpp>
#include <parameters/param.h>
#include <perf/perf_counter.h>
#include <px4_platform_common/module.h>
#include <px4_platform_common/module_params.h>
#include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>
#include <lib/airspeed/airspeed.h>
#include <AirspeedValidator.hpp>
#include <systemlib/mavlink_log.h>

#include <uORB/Subscription.hpp>
#include <uORB/topics/airspeed.h>
#include <uORB/topics/airspeed_validated.h>
#include <uORB/topics/estimator_status.h>
#include <uORB/topics/mavlink_log.h>
#include <uORB/topics/parameter_update.h>
#include <uORB/Publication.hpp>
#include <uORB/PublicationMulti.hpp>
#include <uORB/topics/vehicle_acceleration.h>
#include <uORB/topics/vehicle_air_data.h>
#include <uORB/topics/vehicle_attitude.h>
#include <uORB/topics/vehicle_land_detected.h>
#include <uORB/topics/vehicle_local_position.h>
#include <uORB/topics/vehicle_status.h>
#include <uORB/topics/vtol_vehicle_status.h>
#include <uORB/topics/wind_estimate.h>

using namespace time_literals;

static constexpr uint32_t SCHEDULE_INTERVAL{100_ms};    /**< The schedule interval in usec (10 Hz) */

using matrix::Dcmf;
using matrix::Quatf;
using matrix::Vector2f;
using matrix::Vector3f;

class AirspeedModule : public ModuleBase<AirspeedModule>, public ModuleParams,
    public px4::ScheduledWorkItem
{
public:

    AirspeedModule();

    ~AirspeedModule() override;

    /** @see ModuleBase */
    static int task_spawn(int argc, char *argv[]);

    /** @see ModuleBase */
    static int custom_command(int argc, char *argv[]);

    /** @see ModuleBase */
    static int print_usage(const char *reason = nullptr);

    /* run the main loop */
    void Run() override;

    int print_status() override;

private:
    static constexpr int MAX_NUM_AIRSPEED_SENSORS = 3; /**< Support max 3 airspeed sensors */
    enum airspeed_index {
        DISABLED_INDEX = -1,
        GROUND_MINUS_WIND_INDEX,
        FIRST_SENSOR_INDEX,
        SECOND_SENSOR_INDEX,
        THIRD_SENSOR_INDEX
    };

    uORB::Publication<airspeed_validated_s> _airspeed_validated_pub {ORB_ID(airspeed_validated)};           /**< airspeed validated topic*/
    uORB::PublicationMulti<wind_estimate_s> _wind_est_pub[MAX_NUM_AIRSPEED_SENSORS + 1] {{ORB_ID(wind_estimate)}, {ORB_ID(wind_estimate)}, {ORB_ID(wind_estimate)}, {ORB_ID(wind_estimate)}}; /**< wind estimate topic (for each airspeed validator + purely sideslip fusion) */
    orb_advert_t    _mavlink_log_pub {nullptr};                         /**< mavlink log topic*/

    uORB::Subscription _estimator_status_sub{ORB_ID(estimator_status)};
    uORB::Subscription _param_sub{ORB_ID(parameter_update)};
    uORB::Subscription _vehicle_acceleration_sub{ORB_ID(vehicle_acceleration)};
    uORB::Subscription _vehicle_air_data_sub{ORB_ID(vehicle_air_data)};
    uORB::Subscription _vehicle_attitude_sub{ORB_ID(vehicle_attitude)};
    uORB::Subscription _vehicle_land_detected_sub{ORB_ID(vehicle_land_detected)};
    uORB::Subscription _vehicle_local_position_sub{ORB_ID(vehicle_local_position)};
    uORB::Subscription _vehicle_status_sub{ORB_ID(vehicle_status)};
    uORB::Subscription _vtol_vehicle_status_sub{ORB_ID(vtol_vehicle_status)};
    uORB::Subscription _airspeed_sub[MAX_NUM_AIRSPEED_SENSORS] {{ORB_ID(airspeed), 0}, {ORB_ID(airspeed), 1}, {ORB_ID(airspeed), 2}}; /**< raw airspeed topics subscriptions. */

    estimator_status_s _estimator_status {};
    vehicle_acceleration_s _accel {};
    vehicle_air_data_s _vehicle_air_data {};
    vehicle_attitude_s _vehicle_attitude {};
    vehicle_land_detected_s _vehicle_land_detected {};
    vehicle_local_position_s _vehicle_local_position {};
    vehicle_status_s _vehicle_status {};
    vtol_vehicle_status_s _vtol_vehicle_status {};

    WindEstimator   _wind_estimator_sideslip; /**< wind estimator instance only fusing sideslip */
    wind_estimate_s _wind_estimate_sideslip {}; /**< wind estimate message for wind estimator instance only fusing sideslip */

    int32_t _number_of_airspeed_sensors{0}; /**<  number of airspeed sensors in use (detected during initialization)*/
    int32_t _prev_number_of_airspeed_sensors{0}; /**<  number of airspeed sensors in previous loop (to detect a new added sensor)*/
    AirspeedValidator _airspeed_validator[MAX_NUM_AIRSPEED_SENSORS] {}; /**< airspeedValidator instances (one for each sensor) */

    hrt_abstime _time_now_usec{0};
    int _valid_airspeed_index{-2}; /**< index of currently chosen (valid) airspeed sensor */
    int _prev_airspeed_index{-2}; /**< previously chosen airspeed sensor index */
    bool _initialized{false}; /**< module initialized*/
    bool _vehicle_local_position_valid{false}; /**< local position (from GPS) valid */
    bool _in_takeoff_situation{true}; /**< in takeoff situation (defined as not yet stall speed reached) */
    float _ground_minus_wind_TAS{0.0f}; /**< true airspeed from groundspeed minus windspeed */
    float _ground_minus_wind_EAS{0.0f}; /**< equivalent airspeed from groundspeed minus windspeed */

    bool _scale_estimation_previously_on{false}; /**< scale_estimation was on in the last cycle */

    perf_counter_t _perf_elapsed{};

    DEFINE_PARAMETERS(
        (ParamFloat<px4::params::ASPD_W_P_NOISE>) _param_west_w_p_noise,
        (ParamFloat<px4::params::ASPD_SC_P_NOISE>) _param_west_sc_p_noise,
        (ParamFloat<px4::params::ASPD_TAS_NOISE>) _param_west_tas_noise,
        (ParamFloat<px4::params::ASPD_BETA_NOISE>) _param_west_beta_noise,
        (ParamInt<px4::params::ASPD_TAS_GATE>) _param_west_tas_gate,
        (ParamInt<px4::params::ASPD_BETA_GATE>) _param_west_beta_gate,
        (ParamInt<px4::params::ASPD_SCALE_EST>) _param_west_scale_estimation_on,
        (ParamFloat<px4::params::ASPD_SCALE>) _param_west_airspeed_scale,
        (ParamInt<px4::params::ASPD_PRIMARY>) _param_airspeed_primary_index,
        (ParamInt<px4::params::ASPD_DO_CHECKS>) _param_airspeed_checks_on,
        (ParamInt<px4::params::ASPD_FALLBACK>) _param_airspeed_fallback,

        (ParamFloat<px4::params::ASPD_FS_INNOV>) _tas_innov_threshold, /**< innovation check threshold */
        (ParamFloat<px4::params::ASPD_FS_INTEG>) _tas_innov_integ_threshold, /**< innovation check integrator threshold */
        (ParamInt<px4::params::ASPD_FS_T1>) _checks_fail_delay, /**< delay to declare airspeed invalid */
        (ParamInt<px4::params::ASPD_FS_T2>) _checks_clear_delay, /**<  delay to declare airspeed valid again */
        (ParamFloat<px4::params::ASPD_STALL>) _airspeed_stall /**<  stall speed*/
    )

    void        init();     /**< initialization of the airspeed validator instances */
    void        check_for_connected_airspeed_sensors(); /**< check for airspeed sensors (airspeed topics) and get _number_of_airspeed_sensors */
    void        update_params(); /**< update parameters */
    void        poll_topics(); /**< poll all topics required beside airspeed (e.g. current temperature) */
    void        update_wind_estimator_sideslip(); /**< update the wind estimator instance only fusing sideslip */
    void        update_ground_minus_wind_airspeed(); /**< update airspeed estimate based on groundspeed minus windspeed */
    void        select_airspeed_and_publish(); /**< select airspeed sensor (or groundspeed-windspeed) */

};

AirspeedModule::AirspeedModule():
    ModuleParams(nullptr),
    ScheduledWorkItem(MODULE_NAME, px4::wq_configurations::att_pos_ctrl)
{
    // initialise parameters
    update_params();

    _perf_elapsed = perf_alloc_once(PC_ELAPSED, "airspeed_selector elapsed");
}

AirspeedModule::~AirspeedModule()
{
    ScheduleClear();

    perf_free(_perf_elapsed);

}

int
AirspeedModule::task_spawn(int argc, char *argv[])
{
    AirspeedModule *dev = new AirspeedModule();

    // check if the trampoline is called for the first time
    if (!dev) {
        PX4_ERR("alloc failed");
        return PX4_ERROR;
    }

    _object.store(dev);

    dev->ScheduleOnInterval(SCHEDULE_INTERVAL, 10000);
    _task_id = task_id_is_work_queue;
    return PX4_OK;

}
void
AirspeedModule::init()
{
    check_for_connected_airspeed_sensors();

    /* Set the default sensor */
    if (_param_airspeed_primary_index.get() > _number_of_airspeed_sensors) {
        /* constrain the index to the number of sensors connected*/
        _valid_airspeed_index = math::min(_param_airspeed_primary_index.get(), _number_of_airspeed_sensors);

        if (_number_of_airspeed_sensors == 0) {
            mavlink_and_console_log_info(&_mavlink_log_pub,
                             "No airspeed sensor detected. Switch to non-airspeed mode.");

        } else {
            mavlink_and_console_log_info(&_mavlink_log_pub,
                             "Primary airspeed index bigger than number connected sensors. Take last sensor.");
        }

    } else {
        _valid_airspeed_index =
            _param_airspeed_primary_index.get(); // set index to the one provided in the parameter ASPD_PRIMARY
    }

    _prev_airspeed_index = _valid_airspeed_index; // needed to detect a switching
}

void
AirspeedModule::check_for_connected_airspeed_sensors()
{
    /* check for new connected airspeed sensor */
    int detected_airspeed_sensors = 0;

    if (_param_airspeed_primary_index.get() > 0) {

        for (int i = 0; i < MAX_NUM_AIRSPEED_SENSORS; i++) {
            if (!_airspeed_sub[i].advertised()) {
                break;
            }

            detected_airspeed_sensors = i + 1;
        }

    } else {
        detected_airspeed_sensors = 0; //user has selected groundspeed-windspeed as primary source, or disabled airspeed
    }

    _number_of_airspeed_sensors = detected_airspeed_sensors;
}


void
AirspeedModule::Run()
{
    perf_begin(_perf_elapsed);

    if (!_initialized) {
        init(); // initialize airspeed validator instances
        _initialized = true;
    }

    parameter_update_s update;

    if (_param_sub.update(&update)) {
        update_params();
    }

    _time_now_usec = hrt_absolute_time(); //hrt time of the current cycle

    bool armed = (_vehicle_status.arming_state == vehicle_status_s::ARMING_STATE_ARMED);

    /* Check for new connected airspeed sensors as long as we're disarmed */
    if (!armed) {
        check_for_connected_airspeed_sensors();
    }

    poll_topics();
    update_wind_estimator_sideslip();
    update_ground_minus_wind_airspeed();

    if (_number_of_airspeed_sensors > 0) {

        bool fixed_wing = !_vtol_vehicle_status.vtol_in_rw_mode;
        bool in_air = !_vehicle_land_detected.landed;

        /* Prepare data for airspeed_validator */
        struct airspeed_validator_update_data input_data = {};
        input_data.timestamp = _time_now_usec;
        input_data.lpos_vx = _vehicle_local_position.vx;
        input_data.lpos_vy = _vehicle_local_position.vy;
        input_data.lpos_vz = _vehicle_local_position.vz;
        input_data.lpos_valid = _vehicle_local_position_valid;
        input_data.lpos_evh = _vehicle_local_position.evh;
        input_data.lpos_evv = _vehicle_local_position.evv;
        input_data.att_q[0] = _vehicle_attitude.q[0];
        input_data.att_q[1] = _vehicle_attitude.q[1];
        input_data.att_q[2] = _vehicle_attitude.q[2];
        input_data.att_q[3] = _vehicle_attitude.q[3];
        input_data.air_pressure_pa = _vehicle_air_data.baro_pressure_pa;
        input_data.accel_z = _accel.xyz[2];
        input_data.vel_test_ratio = _estimator_status.vel_test_ratio;
        input_data.mag_test_ratio = _estimator_status.mag_test_ratio;

        /* iterate through all airspeed sensors, poll new data from them and update their validators */
        for (int i = 0; i < _number_of_airspeed_sensors; i++) {

            /* poll airspeed data */
            airspeed_s airspeed_raw = {};
            _airspeed_sub[i].copy(&airspeed_raw); // poll raw airspeed topic of the i-th sensor
            input_data.airspeed_indicated_raw = airspeed_raw.indicated_airspeed_m_s;
            input_data.airspeed_true_raw = airspeed_raw.true_airspeed_m_s;
            input_data.airspeed_timestamp = airspeed_raw.timestamp;
            input_data.air_temperature_celsius = airspeed_raw.air_temperature_celsius;

            /* update in_fixed_wing_flight for the current airspeed sensor validator */
            /* takeoff situation is active from start till one of the sensors' IAS or groundspeed_EAS is above stall speed */
            if (airspeed_raw.indicated_airspeed_m_s > _airspeed_stall.get() || _ground_minus_wind_EAS > _airspeed_stall.get()) {
                _in_takeoff_situation = false;
            }

            /* reset takeoff_situation to true when not in air or not in fixed-wing mode */
            if (!in_air || !fixed_wing) {
                _in_takeoff_situation = true;
            }

            input_data.in_fixed_wing_flight = (armed && fixed_wing && in_air && !_in_takeoff_situation);

            /* push input data into airspeed validator */
            _airspeed_validator[i].update_airspeed_validator(input_data);

        }
    }

    select_airspeed_and_publish();

    perf_end(_perf_elapsed);

    if (should_exit()) {
        exit_and_cleanup();
    }
}

void AirspeedModule::update_params()
{
    updateParams();

    /* update wind estimator (sideslip fusion only) parameters */
    _wind_estimator_sideslip.set_wind_p_noise(_param_west_w_p_noise.get());
    _wind_estimator_sideslip.set_tas_scale_p_noise(_param_west_sc_p_noise.get());
    _wind_estimator_sideslip.set_tas_noise(_param_west_tas_noise.get());
    _wind_estimator_sideslip.set_beta_noise(_param_west_beta_noise.get());
    _wind_estimator_sideslip.set_tas_gate(_param_west_tas_gate.get());
    _wind_estimator_sideslip.set_beta_gate(_param_west_beta_gate.get());

    /* update airspeedValidator parameters */
    for (int i = 0; i < _number_of_airspeed_sensors; i++) {
        _airspeed_validator[i].set_wind_estimator_wind_p_noise(_param_west_w_p_noise.get());
        _airspeed_validator[i].set_wind_estimator_tas_scale_p_noise(_param_west_sc_p_noise.get());
        _airspeed_validator[i].set_wind_estimator_tas_noise(_param_west_tas_noise.get());
        _airspeed_validator[i].set_wind_estimator_beta_noise(_param_west_beta_noise.get());
        _airspeed_validator[i].set_wind_estimator_tas_gate(_param_west_tas_gate.get());
        _airspeed_validator[i].set_wind_estimator_beta_gate(_param_west_beta_gate.get());
        _airspeed_validator[i].set_wind_estimator_scale_estimation_on(_param_west_scale_estimation_on.get());

        /* Only apply manual entered airspeed scale to first airspeed measurement */
        // TODO: enable multiple airspeed sensors
        _airspeed_validator[0].set_airspeed_scale_manual(_param_west_airspeed_scale.get());

        _airspeed_validator[i].set_tas_innov_threshold(_tas_innov_threshold.get());
        _airspeed_validator[i].set_tas_innov_integ_threshold(_tas_innov_integ_threshold.get());
        _airspeed_validator[i].set_checks_fail_delay(_checks_fail_delay.get());
        _airspeed_validator[i].set_checks_clear_delay(_checks_clear_delay.get());
        _airspeed_validator[i].set_airspeed_stall(_airspeed_stall.get());
    }

    /* when airspeed scale estimation is turned on and the airspeed is valid, then set the scale inside the wind estimator to -1 such that it starts to estimate it */
    if (!_scale_estimation_previously_on && _param_west_scale_estimation_on.get()) {
        if (_valid_airspeed_index > 0) {
            _airspeed_validator[0].set_airspeed_scale_manual(
                -1.0f);  // set it to a negative value to start estimation inside wind estimator

        } else {
            mavlink_and_console_log_info(&_mavlink_log_pub, "Airspeed: can't estimate scale as no valid sensor.");
            _param_west_scale_estimation_on.set(0); // reset this param to 0 as estimation was not turned on
            _param_west_scale_estimation_on.commit_no_notification();
        }

        /* If one sensor is valid and we switched out of scale estimation, then publish message and change the value of param ASPD_ASPD_SCALE */

    } else if (_scale_estimation_previously_on && !_param_west_scale_estimation_on.get()) {
        if (_valid_airspeed_index > 0) {

            _param_west_airspeed_scale.set(_airspeed_validator[_valid_airspeed_index - 1].get_EAS_scale());
            _param_west_airspeed_scale.commit_no_notification();
            _airspeed_validator[_valid_airspeed_index - 1].set_airspeed_scale_manual(_param_west_airspeed_scale.get());

            mavlink_and_console_log_info(&_mavlink_log_pub, "Airspeed: estimated scale (ASPD_ASPD_SCALE): %0.2f",
                             (double)_airspeed_validator[_valid_airspeed_index - 1].get_EAS_scale());

        } else {
            mavlink_and_console_log_info(&_mavlink_log_pub, "Airspeed: can't estimate scale as no valid sensor.");
        }
    }

    _scale_estimation_previously_on = _param_west_scale_estimation_on.get();

}

void AirspeedModule::poll_topics()
{
    _estimator_status_sub.update(&_estimator_status);
    _vehicle_acceleration_sub.update(&_accel);
    _vehicle_air_data_sub.update(&_vehicle_air_data);
    _vehicle_attitude_sub.update(&_vehicle_attitude);
    _vehicle_land_detected_sub.update(&_vehicle_land_detected);
    _vehicle_status_sub.update(&_vehicle_status);
    _vtol_vehicle_status_sub.update(&_vtol_vehicle_status);
    _vehicle_local_position_sub.update(&_vehicle_local_position);

    _vehicle_local_position_valid = (_time_now_usec - _vehicle_local_position.timestamp < 1_s)
                    && (_vehicle_local_position.timestamp > 0) && _vehicle_local_position.v_xy_valid;
}

void AirspeedModule::update_wind_estimator_sideslip()
{
    bool att_valid = true; // TODO: check if attitude is valid

    /* update wind and airspeed estimator */
    _wind_estimator_sideslip.update(_time_now_usec);

    if (_vehicle_local_position_valid && att_valid) {
        Vector3f vI(_vehicle_local_position.vx, _vehicle_local_position.vy, _vehicle_local_position.vz);
        Quatf q(_vehicle_attitude.q);

        /* sideslip fusion */
        _wind_estimator_sideslip.fuse_beta(_time_now_usec, vI, q);
    }

    /* fill message for publishing later */
    _wind_estimate_sideslip.timestamp = _time_now_usec;
    float wind[2];
    _wind_estimator_sideslip.get_wind(wind);
    _wind_estimate_sideslip.windspeed_north = wind[0];
    _wind_estimate_sideslip.windspeed_east = wind[1];
    float wind_cov[2];
    _wind_estimator_sideslip.get_wind_var(wind_cov);
    _wind_estimate_sideslip.variance_north = wind_cov[0];
    _wind_estimate_sideslip.variance_east = wind_cov[1];
    _wind_estimate_sideslip.tas_innov = _wind_estimator_sideslip.get_tas_innov();
    _wind_estimate_sideslip.tas_innov_var = _wind_estimator_sideslip.get_tas_innov_var();
    _wind_estimate_sideslip.beta_innov = _wind_estimator_sideslip.get_beta_innov();
    _wind_estimate_sideslip.beta_innov_var = _wind_estimator_sideslip.get_beta_innov_var();
    _wind_estimate_sideslip.tas_scale = _wind_estimator_sideslip.get_tas_scale();
}

void AirspeedModule::update_ground_minus_wind_airspeed()
{
    /* calculate airspeed estimate based on groundspeed-windspeed to use as fallback */
    float TAS_north = _vehicle_local_position.vx - _wind_estimate_sideslip.windspeed_north;
    float TAS_east = _vehicle_local_position.vy - _wind_estimate_sideslip.windspeed_east;
    float TAS_down = _vehicle_local_position.vz; // no wind estimate in z
    _ground_minus_wind_TAS = sqrtf(TAS_north * TAS_north + TAS_east * TAS_east + TAS_down * TAS_down);
    _ground_minus_wind_EAS = calc_EAS_from_TAS(_ground_minus_wind_TAS, _vehicle_air_data.baro_pressure_pa,
                 _vehicle_air_data.baro_temp_celcius);
}


void AirspeedModule::select_airspeed_and_publish()
{
    /* Find new valid index if airspeed currently is invalid, but we have sensors, primary sensor is real sensor and checks are enabled or new sensor was added. */
    bool airspeed_sensor_switching_necessary = _prev_airspeed_index < airspeed_index::FIRST_SENSOR_INDEX ||
            !_airspeed_validator[_prev_airspeed_index - 1].get_airspeed_valid();
    bool airspeed_sensor_switching_allowed = _number_of_airspeed_sensors > 0 &&
            _param_airspeed_primary_index.get() > airspeed_index::GROUND_MINUS_WIND_INDEX && _param_airspeed_checks_on.get();
    bool airspeed_sensor_added = _prev_number_of_airspeed_sensors < _number_of_airspeed_sensors;

    if (airspeed_sensor_switching_necessary && (airspeed_sensor_switching_allowed || airspeed_sensor_added)) {

        _valid_airspeed_index = airspeed_index::DISABLED_INDEX; // set to disabled

        /* Loop through all sensors and take the first valid one */
        for (int i = 0; i < _number_of_airspeed_sensors; i++) {
            if (_airspeed_validator[i].get_airspeed_valid()) {
                _valid_airspeed_index = i + 1;
                break;
            }
        }
    }

    /* Airspeed enabled by user (Primary set to > -1), and no valid airspeed sensor available or primary set to 0. Thus set index to ground-wind one (if position is valid), otherwise to disabled*/
    if (_param_airspeed_primary_index.get() > airspeed_index::DISABLED_INDEX &&
        (_valid_airspeed_index < airspeed_index::FIRST_SENSOR_INDEX
         || _param_airspeed_primary_index.get() == airspeed_index::GROUND_MINUS_WIND_INDEX)) {

        /* _vehicle_local_position_valid determines if ground-wind estimate is valid */
        /* To use ground-windspeed as airspeed source, either the primary has to be set this way or fallback be enabled */
        if (_vehicle_local_position_valid && (_param_airspeed_fallback.get()
                              || _param_airspeed_primary_index.get() == airspeed_index::GROUND_MINUS_WIND_INDEX)) {
            _valid_airspeed_index = airspeed_index::GROUND_MINUS_WIND_INDEX;

        } else {
            _valid_airspeed_index = airspeed_index::DISABLED_INDEX;
        }
    }

    /* publish critical message (and log) in index has changed */
    /* Suppress log message if still on the ground and no airspeed sensor connected */
    if (_valid_airspeed_index != _prev_airspeed_index && (_number_of_airspeed_sensors > 0
            || !_vehicle_land_detected.landed)) {
        mavlink_log_critical(&_mavlink_log_pub, "Airspeed: switched from sensor %i to %i", _prev_airspeed_index,
                     _valid_airspeed_index);
    }

    _prev_airspeed_index = _valid_airspeed_index;
    _prev_number_of_airspeed_sensors = _number_of_airspeed_sensors;

    /* fill out airspeed_validated message for publishing it */
    airspeed_validated_s airspeed_validated = {};
    airspeed_validated.timestamp = _time_now_usec;
    airspeed_validated.true_ground_minus_wind_m_s = NAN;
    airspeed_validated.equivalent_ground_minus_wind_m_s = NAN;
    airspeed_validated.indicated_airspeed_m_s = NAN;
    airspeed_validated.equivalent_airspeed_m_s = NAN;
    airspeed_validated.true_airspeed_m_s = NAN;
    airspeed_validated.airspeed_sensor_measurement_valid = false;
    airspeed_validated.selected_airspeed_index = _valid_airspeed_index;

    switch (_valid_airspeed_index) {
    case airspeed_index::DISABLED_INDEX:
        break;

    case airspeed_index::GROUND_MINUS_WIND_INDEX:
        /* Take IAS, EAS, TAS from groundspeed-windspeed */
        airspeed_validated.indicated_airspeed_m_s = _ground_minus_wind_EAS;
        airspeed_validated.equivalent_airspeed_m_s = _ground_minus_wind_EAS;
        airspeed_validated.true_airspeed_m_s = _ground_minus_wind_TAS;
        airspeed_validated.equivalent_ground_minus_wind_m_s = _ground_minus_wind_EAS;
        airspeed_validated.true_ground_minus_wind_m_s = _ground_minus_wind_TAS;

        break;

    default:
        airspeed_validated.indicated_airspeed_m_s = _airspeed_validator[_valid_airspeed_index - 1].get_IAS();
        airspeed_validated.equivalent_airspeed_m_s = _airspeed_validator[_valid_airspeed_index - 1].get_EAS();
        airspeed_validated.true_airspeed_m_s = _airspeed_validator[_valid_airspeed_index - 1].get_TAS();
        airspeed_validated.equivalent_ground_minus_wind_m_s = _ground_minus_wind_EAS;
        airspeed_validated.true_ground_minus_wind_m_s = _ground_minus_wind_TAS;
        airspeed_validated.airspeed_sensor_measurement_valid = true;
        break;
    }

    /* publish airspeed validated topic */
    _airspeed_validated_pub.publish(airspeed_validated);

    /* publish sideslip-only-fusion wind topic */
    _wind_est_pub[0].publish(_wind_estimate_sideslip);

    /* publish the wind estimator states from all airspeed validators */
    for (int i = 0; i < _number_of_airspeed_sensors; i++) {
        wind_estimate_s wind_est = _airspeed_validator[i].get_wind_estimator_states(_time_now_usec);
        _wind_est_pub[i + 1].publish(wind_est);
    }

}

int AirspeedModule::custom_command(int argc, char *argv[])
{
    if (!is_running()) {
        int ret = AirspeedModule::task_spawn(argc, argv);

        if (ret) {
            return ret;
        }
    }

    return print_usage("unknown command");
}

int AirspeedModule::print_status()
{
    perf_print_counter(_perf_elapsed);

    int instance = 0;
    uORB::SubscriptionData<airspeed_validated_s> est{ORB_ID(airspeed_validated), (uint8_t)instance};
    est.update();
    PX4_INFO("Number of airspeed sensors: %i", _number_of_airspeed_sensors);
    print_message(est.get());

    return 0;
}

int AirspeedModule::print_usage(const char *reason)
{
    if (reason) {
        PX4_WARN("%s\n", reason);
    }

    PRINT_MODULE_DESCRIPTION(
        R"DESCR_STR(
### Description
This module provides a single airspeed_validated topic, containing an indicated (IAS),
equivalent (EAS), true airspeed (TAS) and the information if the estimation currently
is invalid and if based sensor readings or on groundspeed minus windspeed.
Supporting the input of multiple "raw" airspeed inputs, this module automatically switches
to a valid sensor in case of failure detection. For failure detection as well as for
the estimation of a scale factor from IAS to EAS, it runs several wind estimators
and also publishes those.

)DESCR_STR");

    PRINT_MODULE_USAGE_NAME("airspeed_estimator", "estimator");
    PRINT_MODULE_USAGE_COMMAND("start");
    PRINT_MODULE_USAGE_DEFAULT_COMMANDS();

    return 0;
}

extern "C" __EXPORT int airspeed_selector_main(int argc, char *argv[])
{
    return AirspeedModule::main(argc, argv);
}