path: root/src/modules/ekf_att_pos_estimator/ekf_att_pos_estimator_main.cpp

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 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
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/**
 * @file ekf_att_pos_estimator_main.cpp
 * Implementation of the attitude and position estimator.
 *
 * @author Paul Riseborough <p_riseborough@live.com.au>
 * @author Lorenz Meier <lm@inf.ethz.ch>
 */

#include <nuttx/config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <math.h>
#include <poll.h>
#include <time.h>
#include <float.h>

#define SENSOR_COMBINED_SUB

#include <drivers/drv_hrt.h>
#include <drivers/drv_gyro.h>
#include <drivers/drv_accel.h>
#include <drivers/drv_mag.h>
#include <drivers/drv_baro.h>
#ifdef SENSOR_COMBINED_SUB
#include <uORB/topics/sensor_combined.h>
#endif
#include <arch/board/board.h>
#include <uORB/uORB.h>
#include <uORB/topics/airspeed.h>
#include <uORB/topics/vehicle_global_position.h>
#include <uORB/topics/vehicle_local_position.h>
#include <uORB/topics/vehicle_gps_position.h>
#include <uORB/topics/vehicle_attitude.h>
#include <uORB/topics/actuator_controls.h>
#include <uORB/topics/vehicle_status.h>
#include <uORB/topics/parameter_update.h>
#include <uORB/topics/estimator_status.h>
#include <uORB/topics/actuator_armed.h>
#include <uORB/topics/home_position.h>
#include <uORB/topics/wind_estimate.h>
#include <systemlib/param/param.h>
#include <systemlib/err.h>
#include <geo/geo.h>
#include <systemlib/perf_counter.h>
#include <systemlib/systemlib.h>
#include <mathlib/mathlib.h>
#include <mavlink/mavlink_log.h>

#include "estimator_23states.h"



/**
 * estimator app start / stop handling function
 *
 * @ingroup apps
 */
extern "C" __EXPORT int ekf_att_pos_estimator_main(int argc, char *argv[]);

__EXPORT uint32_t millis();

static uint64_t IMUmsec = 0;
static const uint64_t FILTER_INIT_DELAY = 1 * 1000 * 1000;

uint32_t millis()
{
	return IMUmsec;
}

class FixedwingEstimator
{
public:
	/**
	 * Constructor
	 */
	FixedwingEstimator();

	/**
	 * Destructor, also kills the sensors task.
	 */
	~FixedwingEstimator();

	/**
	 * Start the sensors task.
	 *
	 * @return	OK on success.
	 */
	int		start();

	/**
	 * Print the current status.
	 */
	void		print_status();

	/**
	 * Trip the filter by feeding it NaN values.
	 */
	int		trip_nan();

	/**
	 * Enable logging.
	 *
	 * @param	enable Set to true to enable logging, false to disable
	 */
	int		enable_logging(bool enable);

	/**
	 * Set debug level.
	 *
	 * @param	debug Desired debug level - 0 to disable.
	 */
	int		set_debuglevel(unsigned debug) { _debug = debug; return 0; }

private:

	bool		_task_should_exit;		/**< if true, sensor task should exit */
	int		_estimator_task;			/**< task handle for sensor task */
#ifndef SENSOR_COMBINED_SUB
	int		_gyro_sub;			/**< gyro sensor subscription */
	int		_accel_sub;			/**< accel sensor subscription */
	int		_mag_sub;			/**< mag sensor subscription */
#else
	int		_sensor_combined_sub;
#endif
	int		_airspeed_sub;			/**< airspeed subscription */
	int		_baro_sub;			/**< barometer subscription */
	int		_gps_sub;			/**< GPS subscription */
	int		_vstatus_sub;			/**< vehicle status subscription */
	int 		_params_sub;			/**< notification of parameter updates */
	int 		_manual_control_sub;		/**< notification of manual control updates */
	int		_mission_sub;
	int		_home_sub;			/**< home position as defined by commander / user */

	orb_advert_t	_att_pub;			/**< vehicle attitude */
	orb_advert_t	_global_pos_pub;		/**< global position */
	orb_advert_t	_local_pos_pub;			/**< position in local frame */
	orb_advert_t	_estimator_status_pub;		/**< status of the estimator */
	orb_advert_t	_wind_pub;			/**< wind estimate */

	struct vehicle_attitude_s			_att;			/**< vehicle attitude */
	struct gyro_report				_gyro;
	struct accel_report				_accel;
	struct mag_report				_mag;
	struct airspeed_s				_airspeed;		/**< airspeed */
	struct baro_report				_baro;			/**< baro readings */
	struct vehicle_status_s				_vstatus;		/**< vehicle status */
	struct vehicle_global_position_s		_global_pos;		/**< global vehicle position */
	struct vehicle_local_position_s			_local_pos;		/**< local vehicle position */
	struct vehicle_gps_position_s			_gps;			/**< GPS position */
	struct wind_estimate_s				_wind;			/**< Wind estimate */

	struct gyro_scale				_gyro_offsets;
	struct accel_scale				_accel_offsets;
	struct mag_scale				_mag_offsets;

#ifdef SENSOR_COMBINED_SUB
	struct sensor_combined_s			_sensor_combined;
#endif

	struct map_projection_reference_s	_pos_ref;

	float						_baro_ref;		/**< barometer reference altitude */
	float						_baro_ref_offset;	/**< offset between initial baro reference and GPS init baro altitude */
	float						_baro_gps_offset;	/**< offset between baro altitude (at GPS init time) and GPS altitude */

	perf_counter_t	_loop_perf;			///< loop performance counter
	perf_counter_t	_perf_gyro;			///<local performance counter for gyro updates
	perf_counter_t	_perf_mag;			///<local performance counter for mag updates
	perf_counter_t	_perf_gps;			///<local performance counter for gps updates
	perf_counter_t	_perf_baro;			///<local performance counter for baro updates
	perf_counter_t	_perf_airspeed;			///<local performance counter for airspeed updates
	perf_counter_t	_perf_reset;			///<local performance counter for filter resets

	bool						_baro_init;
	bool						_gps_initialized;
	hrt_abstime					_gps_start_time;
	hrt_abstime					_filter_start_time;
	hrt_abstime					_last_sensor_timestamp;
	hrt_abstime					_last_run;
	bool						_gyro_valid;
	bool						_accel_valid;
	bool						_mag_valid;
	bool						_ekf_logging;		///< log EKF state
	unsigned					_debug;			///< debug level - default 0

	int						_mavlink_fd;

	struct {
		int32_t	vel_delay_ms;
		int32_t	pos_delay_ms;
		int32_t	height_delay_ms;
		int32_t	mag_delay_ms;
		int32_t	tas_delay_ms;
		float velne_noise;
		float veld_noise;
		float posne_noise;
		float posd_noise;
		float mag_noise;
		float gyro_pnoise;
		float acc_pnoise;
		float gbias_pnoise;
		float abias_pnoise;
		float mage_pnoise;
		float magb_pnoise;
		float eas_noise;
		float pos_stddev_threshold;
	}		_parameters;			/**< local copies of interesting parameters */

	struct {
		param_t vel_delay_ms;
		param_t	pos_delay_ms;
		param_t	height_delay_ms;
		param_t	mag_delay_ms;
		param_t	tas_delay_ms;
		param_t velne_noise;
		param_t veld_noise;
		param_t posne_noise;
		param_t posd_noise;
		param_t mag_noise;
		param_t gyro_pnoise;
		param_t acc_pnoise;
		param_t gbias_pnoise;
		param_t abias_pnoise;
		param_t mage_pnoise;
		param_t magb_pnoise;
		param_t eas_noise;
		param_t pos_stddev_threshold;
	}		_parameter_handles;		/**< handles for interesting parameters */

	AttPosEKF					*_ekf;

	float						_velocity_xy_filtered;
	float						_velocity_z_filtered;
	float						_airspeed_filtered;

	/**
	 * Update our local parameter cache.
	 */
	int		parameters_update();

	/**
	 * Update control outputs
	 *
	 */
	void		control_update();

	/**
	 * Check for changes in vehicle status.
	 */
	void		vehicle_status_poll();

	/**
	 * Shim for calling task_main from task_create.
	 */
	static void	task_main_trampoline(int argc, char *argv[]);

	/**
	 * Main filter task.
	 */
	void		task_main();

	/**
	 * Check filter sanity state
	 *
	 * @return zero if ok, non-zero for a filter error condition.
	 */
	int		check_filter_state();
};

namespace estimator
{

/* oddly, ERROR is not defined for c++ */
#ifdef ERROR
# undef ERROR
#endif
static const int ERROR = -1;

FixedwingEstimator	*g_estimator;
}

FixedwingEstimator::FixedwingEstimator() :

	_task_should_exit(false),
	_estimator_task(-1),

/* subscriptions */
#ifndef SENSOR_COMBINED_SUB
	_gyro_sub(-1),
	_accel_sub(-1),
	_mag_sub(-1),
#else
	_sensor_combined_sub(-1),
#endif
	_airspeed_sub(-1),
	_baro_sub(-1),
	_gps_sub(-1),
	_vstatus_sub(-1),
	_params_sub(-1),
	_manual_control_sub(-1),
	_mission_sub(-1),
	_home_sub(-1),

/* publications */
	_att_pub(-1),
	_global_pos_pub(-1),
	_local_pos_pub(-1),
	_estimator_status_pub(-1),
	_wind_pub(-1),

	_att({}),
	_gyro({}),
	_accel({}),
	_mag({}),
	_airspeed({}),
	_baro({}),
	_vstatus({}),
	_global_pos({}),
	_local_pos({}),
	_gps({}),
	_wind({}),

	_gyro_offsets({}),
	_accel_offsets({}),
	_mag_offsets({}),

	#ifdef SENSOR_COMBINED_SUB
	_sensor_combined({}),
	#endif

	_baro_ref(0.0f),
	_baro_ref_offset(0.0f),
	_baro_gps_offset(0.0f),

/* performance counters */
	_loop_perf(perf_alloc(PC_ELAPSED, "ekf_att_pos_estimator")),
	_perf_gyro(perf_alloc(PC_INTERVAL, "ekf_att_pos_gyro_upd")),
	_perf_mag(perf_alloc(PC_INTERVAL, "ekf_att_pos_mag_upd")),
	_perf_gps(perf_alloc(PC_INTERVAL, "ekf_att_pos_gps_upd")),
	_perf_baro(perf_alloc(PC_INTERVAL, "ekf_att_pos_baro_upd")),
	_perf_airspeed(perf_alloc(PC_INTERVAL, "ekf_att_pos_aspd_upd")),
	_perf_reset(perf_alloc(PC_COUNT, "ekf_att_pos_reset")),

/* states */
	_baro_init(false),
	_gps_initialized(false),
	_gyro_valid(false),
	_accel_valid(false),
	_mag_valid(false),
	_ekf_logging(true),
	_debug(0),
	_mavlink_fd(-1),
	_ekf(nullptr),
	_velocity_xy_filtered(0.0f),
	_velocity_z_filtered(0.0f),
	_airspeed_filtered(0.0f)
{

	_last_run = hrt_absolute_time();

	_parameter_handles.vel_delay_ms = param_find("PE_VEL_DELAY_MS");
	_parameter_handles.pos_delay_ms = param_find("PE_POS_DELAY_MS");
	_parameter_handles.height_delay_ms = param_find("PE_HGT_DELAY_MS");
	_parameter_handles.mag_delay_ms = param_find("PE_MAG_DELAY_MS");
	_parameter_handles.tas_delay_ms = param_find("PE_TAS_DELAY_MS");
	_parameter_handles.velne_noise = param_find("PE_VELNE_NOISE");
	_parameter_handles.veld_noise = param_find("PE_VELD_NOISE");
	_parameter_handles.posne_noise = param_find("PE_POSNE_NOISE");
	_parameter_handles.posd_noise = param_find("PE_POSD_NOISE");
	_parameter_handles.mag_noise = param_find("PE_MAG_NOISE");
	_parameter_handles.gyro_pnoise = param_find("PE_GYRO_PNOISE");
	_parameter_handles.acc_pnoise = param_find("PE_ACC_PNOISE");
	_parameter_handles.gbias_pnoise = param_find("PE_GBIAS_PNOISE");
	_parameter_handles.abias_pnoise = param_find("PE_ABIAS_PNOISE");
	_parameter_handles.mage_pnoise = param_find("PE_MAGE_PNOISE");
	_parameter_handles.magb_pnoise = param_find("PE_MAGB_PNOISE");
	_parameter_handles.eas_noise = param_find("PE_EAS_NOISE");
	_parameter_handles.pos_stddev_threshold = param_find("PE_POSDEV_INIT");

	/* fetch initial parameter values */
	parameters_update();

	/* get offsets */

	int fd, res;

	fd = open(GYRO_DEVICE_PATH, O_RDONLY);

	if (fd > 0) {
		res = ioctl(fd, GYROIOCGSCALE, (long unsigned int)&_gyro_offsets);
		close(fd);

		if (res) {
			warnx("G SCALE FAIL");
		}
	}

	fd = open(ACCEL_DEVICE_PATH, O_RDONLY);

	if (fd > 0) {
		res = ioctl(fd, ACCELIOCGSCALE, (long unsigned int)&_accel_offsets);
		close(fd);

		if (res) {
			warnx("A SCALE FAIL");
		}
	}

	fd = open(MAG_DEVICE_PATH, O_RDONLY);

	if (fd > 0) {
		res = ioctl(fd, MAGIOCGSCALE, (long unsigned int)&_mag_offsets);
		close(fd);

		if (res) {
			warnx("M SCALE FAIL");
		}
	}
}

FixedwingEstimator::~FixedwingEstimator()
{
	if (_estimator_task != -1) {

		/* task wakes up every 100ms or so at the longest */
		_task_should_exit = true;

		/* wait for a second for the task to quit at our request */
		unsigned i = 0;

		do {
			/* wait 20ms */
			usleep(20000);

			/* if we have given up, kill it */
			if (++i > 50) {
				task_delete(_estimator_task);
				break;
			}
		} while (_estimator_task != -1);
	}

	delete _ekf;

	estimator::g_estimator = nullptr;
}

int
FixedwingEstimator::enable_logging(bool logging)
{
	_ekf_logging = logging;

	return 0;
}

int
FixedwingEstimator::parameters_update()
{

	param_get(_parameter_handles.vel_delay_ms, &(_parameters.vel_delay_ms));
	param_get(_parameter_handles.pos_delay_ms, &(_parameters.pos_delay_ms));
	param_get(_parameter_handles.height_delay_ms, &(_parameters.height_delay_ms));
	param_get(_parameter_handles.mag_delay_ms, &(_parameters.mag_delay_ms));
	param_get(_parameter_handles.tas_delay_ms, &(_parameters.tas_delay_ms));
	param_get(_parameter_handles.velne_noise, &(_parameters.velne_noise));
	param_get(_parameter_handles.veld_noise, &(_parameters.veld_noise));
	param_get(_parameter_handles.posne_noise, &(_parameters.posne_noise));
	param_get(_parameter_handles.posd_noise, &(_parameters.posd_noise));
	param_get(_parameter_handles.mag_noise, &(_parameters.mag_noise));
	param_get(_parameter_handles.gyro_pnoise, &(_parameters.gyro_pnoise));
	param_get(_parameter_handles.acc_pnoise, &(_parameters.acc_pnoise));
	param_get(_parameter_handles.gbias_pnoise, &(_parameters.gbias_pnoise));
	param_get(_parameter_handles.abias_pnoise, &(_parameters.abias_pnoise));
	param_get(_parameter_handles.mage_pnoise, &(_parameters.mage_pnoise));
	param_get(_parameter_handles.magb_pnoise, &(_parameters.magb_pnoise));
	param_get(_parameter_handles.eas_noise, &(_parameters.eas_noise));
	param_get(_parameter_handles.pos_stddev_threshold, &(_parameters.pos_stddev_threshold));

	if (_ekf) {
		// _ekf->yawVarScale = 1.0f;
		// _ekf->windVelSigma = 0.1f;
		_ekf->dAngBiasSigma = _parameters.gbias_pnoise;
		_ekf->dVelBiasSigma = _parameters.abias_pnoise;
		_ekf->magEarthSigma = _parameters.mage_pnoise;
		_ekf->magBodySigma  = _parameters.magb_pnoise;
		// _ekf->gndHgtSigma  = 0.02f;
		_ekf->vneSigma = _parameters.velne_noise;
		_ekf->vdSigma = _parameters.veld_noise;
		_ekf->posNeSigma = _parameters.posne_noise;
		_ekf->posDSigma = _parameters.posd_noise;
		_ekf->magMeasurementSigma = _parameters.mag_noise;
		_ekf->gyroProcessNoise = _parameters.gyro_pnoise;
        	_ekf->accelProcessNoise = _parameters.acc_pnoise;
		_ekf->airspeedMeasurementSigma = _parameters.eas_noise;
	}

	return OK;
}

void
FixedwingEstimator::vehicle_status_poll()
{
	bool vstatus_updated;

	/* Check HIL state if vehicle status has changed */
	orb_check(_vstatus_sub, &vstatus_updated);

	if (vstatus_updated) {

		orb_copy(ORB_ID(vehicle_status), _vstatus_sub, &_vstatus);
	}
}

int
FixedwingEstimator::check_filter_state()
{
	/*
	 *    CHECK IF THE INPUT DATA IS SANE
	 */

	struct ekf_status_report ekf_report;

	int check = _ekf->CheckAndBound(&ekf_report);

	const char* ekfname = "att pos estimator: ";

	switch (check) {
		case 0:
			/* all ok */
			break;
		case 1:
		{
			const char* str = "NaN in states, resetting";
			warnx("%s", str);
			mavlink_log_critical(_mavlink_fd, "%s%s", ekfname, str);
			break;
		}
		case 2:
		{
			const char* str = "stale IMU data, resetting";
			warnx("%s", str);
			mavlink_log_critical(_mavlink_fd, "%s%s", ekfname, str);
			break;
		}
		case 3:
		{
			const char* str = "switching to dynamic state";
			warnx("%s", str);
			mavlink_log_info(_mavlink_fd, "%s%s", ekfname, str);
			break;
		}
		case 4:
		{
			const char* str = "excessive gyro offsets";
			warnx("%s", str);
			mavlink_log_info(_mavlink_fd, "%s%s", ekfname, str);
			break;
		}
		case 5:
		{
			const char* str = "GPS velocity divergence";
			warnx("%s", str);
			mavlink_log_info(_mavlink_fd, "%s%s", ekfname, str);
			break;
		}
		case 6:
		{
			const char* str = "excessive covariances";
			warnx("%s", str);
			mavlink_log_info(_mavlink_fd, "%s%s", ekfname, str);
			break;
		}

		default:
		{
			const char* str = "unknown reset condition";
			warnx("%s", str);
			mavlink_log_critical(_mavlink_fd, "%s%s", ekfname, str);
		}
	}

	struct estimator_status_report rep;
	memset(&rep, 0, sizeof(rep));

	// If error flag is set, we got a filter reset
	if (check && ekf_report.error) {

		// Count the reset condition
		perf_count(_perf_reset);

	} else if (_ekf_logging) {
		_ekf->GetFilterState(&ekf_report);
	}

	if (_ekf_logging || check) {
		rep.timestamp = hrt_absolute_time();

		rep.nan_flags |= (((uint8_t)ekf_report.angNaN)		<< 0);
		rep.nan_flags |= (((uint8_t)ekf_report.summedDelVelNaN)	<< 1);
		rep.nan_flags |= (((uint8_t)ekf_report.KHNaN)		<< 2);
		rep.nan_flags |= (((uint8_t)ekf_report.KHPNaN)		<< 3);
		rep.nan_flags |= (((uint8_t)ekf_report.PNaN)		<< 4);
		rep.nan_flags |= (((uint8_t)ekf_report.covarianceNaN)	<< 5);
		rep.nan_flags |= (((uint8_t)ekf_report.kalmanGainsNaN)	<< 6);
		rep.nan_flags |= (((uint8_t)ekf_report.statesNaN)	<< 7);

		rep.health_flags |= (((uint8_t)ekf_report.velHealth)	<< 0);
		rep.health_flags |= (((uint8_t)ekf_report.posHealth)	<< 1);
		rep.health_flags |= (((uint8_t)ekf_report.hgtHealth)	<< 2);
		rep.health_flags |= (((uint8_t)!ekf_report.gyroOffsetsExcessive)	<< 3);

		rep.timeout_flags |= (((uint8_t)ekf_report.velTimeout)	<< 0);
		rep.timeout_flags |= (((uint8_t)ekf_report.posTimeout)	<< 1);
		rep.timeout_flags |= (((uint8_t)ekf_report.hgtTimeout)	<< 2);
		rep.timeout_flags |= (((uint8_t)ekf_report.imuTimeout)	<< 3);

		if (_debug > 10) {

			if (rep.health_flags < ((1 << 0) | (1 << 1) | (1 << 2) | (1 << 3))) {
				warnx("health: VEL:%s POS:%s HGT:%s OFFS:%s",
					((rep.health_flags & (1 << 0)) ? "OK" : "ERR"),
					((rep.health_flags & (1 << 1)) ? "OK" : "ERR"),
					((rep.health_flags & (1 << 2)) ? "OK" : "ERR"),
					((rep.health_flags & (1 << 3)) ? "OK" : "ERR"));
			}

			if (rep.timeout_flags) {
				warnx("timeout: %s%s%s%s",
					((rep.timeout_flags & (1 << 0)) ? "VEL " : ""),
					((rep.timeout_flags & (1 << 1)) ? "POS " : ""),
					((rep.timeout_flags & (1 << 2)) ? "HGT " : ""),
					((rep.timeout_flags & (1 << 3)) ? "IMU " : ""));
			}
		}

		// Copy all states or at least all that we can fit
		unsigned ekf_n_states = ekf_report.n_states;
		unsigned max_states = (sizeof(rep.states) / sizeof(rep.states[0]));
		rep.n_states = (ekf_n_states < max_states) ? ekf_n_states : max_states;

		for (unsigned i = 0; i < rep.n_states; i++) {
			rep.states[i] = ekf_report.states[i];
		}

		for (unsigned i = 0; i < rep.n_states; i++) {
			rep.states[i] = ekf_report.states[i];
		}

		if (_estimator_status_pub > 0) {
			orb_publish(ORB_ID(estimator_status), _estimator_status_pub, &rep);
		} else {
			_estimator_status_pub = orb_advertise(ORB_ID(estimator_status), &rep);
		}
	}

	return check;
}

void
FixedwingEstimator::task_main_trampoline(int argc, char *argv[])
{
	estimator::g_estimator->task_main();
}

void
FixedwingEstimator::task_main()
{
	_mavlink_fd = open(MAVLINK_LOG_DEVICE, 0);

	_ekf = new AttPosEKF();
	float dt = 0.0f; // time lapsed since last covariance prediction
	_filter_start_time = hrt_absolute_time();

	if (!_ekf) {
		errx(1, "OUT OF MEM!");
	}

	/*
	 * do subscriptions
	 */
	_baro_sub = orb_subscribe(ORB_ID(sensor_baro));
	_airspeed_sub = orb_subscribe(ORB_ID(airspeed));
	_gps_sub = orb_subscribe(ORB_ID(vehicle_gps_position));
	_vstatus_sub = orb_subscribe(ORB_ID(vehicle_status));
	_params_sub = orb_subscribe(ORB_ID(parameter_update));
	_home_sub = orb_subscribe(ORB_ID(home_position));

	/* rate limit vehicle status updates to 5Hz */
	orb_set_interval(_vstatus_sub, 200);

#ifndef SENSOR_COMBINED_SUB

	_gyro_sub = orb_subscribe(ORB_ID(sensor_gyro));
	_accel_sub = orb_subscribe(ORB_ID(sensor_accel));
	_mag_sub = orb_subscribe(ORB_ID(sensor_mag));

	/* rate limit gyro updates to 50 Hz */
	/* XXX remove this!, BUT increase the data buffer size! */
	orb_set_interval(_gyro_sub, 4);
#else
	_sensor_combined_sub = orb_subscribe(ORB_ID(sensor_combined));
	/* XXX remove this!, BUT increase the data buffer size! */
	orb_set_interval(_sensor_combined_sub, 9);
#endif

	/* sets also parameters in the EKF object */
	parameters_update();

	Vector3f lastAngRate = {0.0f, 0.0f, 0.0f};
	Vector3f lastAccel = {0.0f, 0.0f, 0.0f};

	/* wakeup source(s) */
	struct pollfd fds[2];

	/* Setup of loop */
	fds[0].fd = _params_sub;
	fds[0].events = POLLIN;
#ifndef SENSOR_COMBINED_SUB
	fds[1].fd = _gyro_sub;
	fds[1].events = POLLIN;
#else
	fds[1].fd = _sensor_combined_sub;
	fds[1].events = POLLIN;
#endif

	bool newDataGps = false;
	bool newHgtData = false;
	bool newAdsData = false;
	bool newDataMag = false;

	float posNED[3] = {0.0f, 0.0f, 0.0f}; // North, East Down position (m)

	uint64_t last_gps = 0;
	_gps.vel_n_m_s = 0.0f;
	_gps.vel_e_m_s = 0.0f;
	_gps.vel_d_m_s = 0.0f;

	while (!_task_should_exit) {

		/* wait for up to 500ms for data */
		int pret = poll(&fds[0], (sizeof(fds) / sizeof(fds[0])), 100);

		/* timed out - periodic check for _task_should_exit, etc. */
		if (pret == 0)
			continue;

		/* this is undesirable but not much we can do - might want to flag unhappy status */
		if (pret < 0) {
			warn("POLL ERR %d, %d", pret, errno);
			continue;
		}

		perf_begin(_loop_perf);

		/* only update parameters if they changed */
		if (fds[0].revents & POLLIN) {
			/* read from param to clear updated flag */
			struct parameter_update_s update;
			orb_copy(ORB_ID(parameter_update), _params_sub, &update);

			/* update parameters from storage */
			parameters_update();
		}

		/* only run estimator if gyro updated */
		if (fds[1].revents & POLLIN) {

			/* check vehicle status for changes to publication state */
			bool prev_hil = (_vstatus.hil_state == HIL_STATE_ON);
			vehicle_status_poll();

			bool accel_updated;
			bool mag_updated;

			perf_count(_perf_gyro);

			/* Reset baro reference if switching to HIL, reset sensor states */
			if (!prev_hil && (_vstatus.hil_state == HIL_STATE_ON)) {
				/* system is in HIL now, wait for measurements to come in one last round */
				usleep(60000);

#ifndef SENSOR_COMBINED_SUB
				orb_copy(ORB_ID(sensor_gyro), _gyro_sub, &_gyro);
				orb_copy(ORB_ID(sensor_accel), _accel_sub, &_accel);
				orb_copy(ORB_ID(sensor_mag), _mag_sub, &_mag);
#else
				/* now read all sensor publications to ensure all real sensor data is purged */
				orb_copy(ORB_ID(sensor_combined), _sensor_combined_sub, &_sensor_combined);
#endif

				/* set sensors to de-initialized state */
				_gyro_valid = false;
				_accel_valid = false;
				_mag_valid = false;

				_baro_init = false;
				_gps_initialized = false;
				_last_sensor_timestamp = hrt_absolute_time();
				_last_run = _last_sensor_timestamp;

				_ekf->ZeroVariables();
				_ekf->dtIMU = 0.01f;
				_filter_start_time = _last_sensor_timestamp;

				/* now skip this loop and get data on the next one, which will also re-init the filter */
				continue;
			}

			/**
			 *    PART ONE: COLLECT ALL DATA
			 **/

			/* load local copies */
#ifndef SENSOR_COMBINED_SUB
			orb_copy(ORB_ID(sensor_gyro), _gyro_sub, &_gyro);


			orb_check(_accel_sub, &accel_updated);

			if (accel_updated) {
				orb_copy(ORB_ID(sensor_accel), _accel_sub, &_accel);
			}

			_last_sensor_timestamp = _gyro.timestamp;
			IMUmsec = _gyro.timestamp / 1e3f;

			float deltaT = (_gyro.timestamp - _last_run) / 1e6f;
			_last_run = _gyro.timestamp;

			/* guard against too large deltaT's */
			if (!isfinite(deltaT) || deltaT > 1.0f || deltaT < 0.000001f) {
				deltaT = 0.01f;
			}


			// Always store data, independent of init status
			/* fill in last data set */
			_ekf->dtIMU = deltaT;

			if (isfinite(_gyro.x) &&
				isfinite(_gyro.y) &&
				isfinite(_gyro.z)) {
				_ekf->angRate.x = _gyro.x;
				_ekf->angRate.y = _gyro.y;
				_ekf->angRate.z = _gyro.z;

				if (!_gyro_valid) {
					lastAngRate = _ekf->angRate;
				}

				_gyro_valid = true;
			}

			if (accel_updated) {
				_ekf->accel.x = _accel.x;
				_ekf->accel.y = _accel.y;
				_ekf->accel.z = _accel.z;

				if (!_accel_valid) {
					lastAccel = _ekf->accel;
				}

				_accel_valid = true;
			}

			_ekf->dAngIMU = 0.5f * (angRate + lastAngRate) * dtIMU;
			_ekf->lastAngRate = angRate;
			_ekf->dVelIMU = 0.5f * (accel + lastAccel) * dtIMU;
			_ekf->lastAccel = accel;


#else
			orb_copy(ORB_ID(sensor_combined), _sensor_combined_sub, &_sensor_combined);

			static hrt_abstime last_accel = 0;
			static hrt_abstime last_mag = 0;

			if (last_accel != _sensor_combined.accelerometer_timestamp) {
				accel_updated = true;
			} else {
				accel_updated = false;
			}

			last_accel = _sensor_combined.accelerometer_timestamp;


			// Copy gyro and accel
			_last_sensor_timestamp = _sensor_combined.timestamp;
			IMUmsec = _sensor_combined.timestamp / 1e3f;

			float deltaT = (_sensor_combined.timestamp - _last_run) / 1e6f;

			/* guard against too large deltaT's */
			if (!isfinite(deltaT) || deltaT > 1.0f || deltaT < 0.000001f) {
				deltaT = 0.01f;
			}

			_last_run = _sensor_combined.timestamp;

			// Always store data, independent of init status
			/* fill in last data set */
			_ekf->dtIMU = deltaT;

			if (isfinite(_sensor_combined.gyro_rad_s[0]) &&
				isfinite(_sensor_combined.gyro_rad_s[1]) &&
				isfinite(_sensor_combined.gyro_rad_s[2])) {
				_ekf->angRate.x = _sensor_combined.gyro_rad_s[0];
				_ekf->angRate.y = _sensor_combined.gyro_rad_s[1];
				_ekf->angRate.z = _sensor_combined.gyro_rad_s[2];

				if (!_gyro_valid) {
					lastAngRate = _ekf->angRate;
				}

				_gyro_valid = true;
				perf_count(_perf_gyro);
			}

			if (accel_updated) {
				_ekf->accel.x = _sensor_combined.accelerometer_m_s2[0];
				_ekf->accel.y = _sensor_combined.accelerometer_m_s2[1];
				_ekf->accel.z = _sensor_combined.accelerometer_m_s2[2];

				if (!_accel_valid) {
					lastAccel = _ekf->accel;
				}

				_accel_valid = true;
			}

			_ekf->dAngIMU = 0.5f * (_ekf->angRate + lastAngRate) * _ekf->dtIMU;
			lastAngRate = _ekf->angRate;
			_ekf->dVelIMU = 0.5f * (_ekf->accel + lastAccel) * _ekf->dtIMU;
			lastAccel = _ekf->accel;

			if (last_mag != _sensor_combined.magnetometer_timestamp) {
				mag_updated = true;
				newDataMag = true;

			} else {
				newDataMag = false;
			}

			last_mag = _sensor_combined.magnetometer_timestamp;

#endif

			//warnx("dang: %8.4f %8.4f dvel: %8.4f %8.4f", _ekf->dAngIMU.x, _ekf->dAngIMU.z, _ekf->dVelIMU.x, _ekf->dVelIMU.z);

			bool airspeed_updated;
			orb_check(_airspeed_sub, &airspeed_updated);

			if (airspeed_updated) {
				orb_copy(ORB_ID(airspeed), _airspeed_sub, &_airspeed);
				perf_count(_perf_airspeed);

				_ekf->VtasMeas = _airspeed.true_airspeed_m_s;
				newAdsData = true;

			} else {
				newAdsData = false;
			}

			bool gps_updated;
			orb_check(_gps_sub, &gps_updated);

			if (gps_updated) {

				last_gps = _gps.timestamp_position;

				orb_copy(ORB_ID(vehicle_gps_position), _gps_sub, &_gps);
				perf_count(_perf_gps);

				if (_gps.fix_type < 3) {
					newDataGps = false;

				} else {

					/* store time of valid GPS measurement */
					_gps_start_time = hrt_absolute_time();

					/* check if we had a GPS outage for a long time */
					if (hrt_elapsed_time(&last_gps) > 5 * 1000 * 1000) {
						_ekf->ResetPosition();
						_ekf->ResetVelocity();
						_ekf->ResetStoredStates();
					}

					/* fuse GPS updates */

					//_gps.timestamp / 1e3;
					_ekf->GPSstatus = _gps.fix_type;
					_ekf->velNED[0] = _gps.vel_n_m_s;
					_ekf->velNED[1] = _gps.vel_e_m_s;
					_ekf->velNED[2] = _gps.vel_d_m_s;

					// warnx("GPS updated: status: %d, vel: %8.4f %8.4f %8.4f", (int)GPSstatus, velNED[0], velNED[1], velNED[2]);

					_ekf->gpsLat = math::radians(_gps.lat / (double)1e7);
					_ekf->gpsLon = math::radians(_gps.lon / (double)1e7) - M_PI;
					_ekf->gpsHgt = _gps.alt / 1e3f;

					// if (_gps.s_variance_m_s > 0.25f && _gps.s_variance_m_s < 100.0f * 100.0f) {
					// 	_ekf->vneSigma = sqrtf(_gps.s_variance_m_s);
					// } else {
					// 	_ekf->vneSigma = _parameters.velne_noise;
					// }

					// if (_gps.p_variance_m > 0.25f && _gps.p_variance_m < 100.0f * 100.0f) {
					// 	_ekf->posNeSigma = sqrtf(_gps.p_variance_m);
					// } else {
					// 	_ekf->posNeSigma = _parameters.posne_noise;
					// }

					// warnx("vel: %8.4f pos: %8.4f", _gps.s_variance_m_s, _gps.p_variance_m);

					newDataGps = true;

				}

			}

			bool baro_updated;
			orb_check(_baro_sub, &baro_updated);

			if (baro_updated) {
				orb_copy(ORB_ID(sensor_baro), _baro_sub, &_baro);

				_ekf->baroHgt = _baro.altitude;

				if (!_baro_init) {
					_baro_ref = _baro.altitude;
					_baro_init = true;
					warnx("ALT REF INIT");
				}

				perf_count(_perf_baro);

				newHgtData = true;
			} else {
				newHgtData = false;
			}

#ifndef SENSOR_COMBINED_SUB
			orb_check(_mag_sub, &mag_updated);
#endif

			if (mag_updated) {

				_mag_valid = true;

				perf_count(_perf_mag);

#ifndef SENSOR_COMBINED_SUB
				orb_copy(ORB_ID(sensor_mag), _mag_sub, &_mag);

				// XXX we compensate the offsets upfront - should be close to zero.
				// 0.001f
				_ekf->magData.x = _mag.x;
				_ekf->magBias.x = 0.000001f; // _mag_offsets.x_offset

				_ekf->magData.y = _mag.y;
				_ekf->magBias.y = 0.000001f; // _mag_offsets.y_offset

				_ekf->magData.z = _mag.z;
				_ekf->magBias.z = 0.000001f; // _mag_offsets.y_offset

#else

				// XXX we compensate the offsets upfront - should be close to zero.
				// 0.001f
				_ekf->magData.x = _sensor_combined.magnetometer_ga[0];
				_ekf->magBias.x = 0.000001f; // _mag_offsets.x_offset

				_ekf->magData.y = _sensor_combined.magnetometer_ga[1];
				_ekf->magBias.y = 0.000001f; // _mag_offsets.y_offset

				_ekf->magData.z = _sensor_combined.magnetometer_ga[2];
				_ekf->magBias.z = 0.000001f; // _mag_offsets.y_offset

#endif

				newDataMag = true;

			} else {
				newDataMag = false;
			}

			/*
			 *    CHECK IF ITS THE RIGHT TIME TO RUN THINGS ALREADY
			 */
			if (hrt_elapsed_time(&_filter_start_time) < FILTER_INIT_DELAY) {
				continue;
			}

			/**
			 *    PART TWO: EXECUTE THE FILTER
			 *
			 *    We run the filter only once all data has been fetched
			 **/

			if (_baro_init && _gyro_valid && _accel_valid && _mag_valid) {

				float initVelNED[3];

				/* Initialize the filter first */
				if (!_gps_initialized && _gps.fix_type > 2 && _gps.eph < _parameters.pos_stddev_threshold && _gps.epv < _parameters.pos_stddev_threshold) {

					// GPS is in scaled integers, convert
					double lat = _gps.lat / 1.0e7;
					double lon = _gps.lon / 1.0e7;
					float gps_alt = _gps.alt / 1e3f;

					initVelNED[0] = _gps.vel_n_m_s;
					initVelNED[1] = _gps.vel_e_m_s;
					initVelNED[2] = _gps.vel_d_m_s;

					// Set up height correctly
					orb_copy(ORB_ID(sensor_baro), _baro_sub, &_baro);
					_baro_ref_offset = _ekf->states[9]; // this should become zero in the local frame
					_baro_gps_offset = _baro.altitude - gps_alt;
					_ekf->baroHgt = _baro.altitude;
					_ekf->hgtMea = 1.0f * (_ekf->baroHgt - (_baro_ref));

					// Set up position variables correctly
					_ekf->GPSstatus = _gps.fix_type;

					_ekf->gpsLat = math::radians(lat);
					_ekf->gpsLon = math::radians(lon) - M_PI;
					_ekf->gpsHgt = gps_alt;

					// Look up mag declination based on current position
					float declination = math::radians(get_mag_declination(lat, lon));

					_ekf->InitialiseFilter(initVelNED, math::radians(lat), math::radians(lon) - M_PI, gps_alt, declination);

					// Initialize projection
					_local_pos.ref_lat = lat;
					_local_pos.ref_lon = lon;
					_local_pos.ref_alt = gps_alt;
					_local_pos.ref_timestamp = _gps.timestamp_position;

					map_projection_init(&_pos_ref, lat, lon);
					mavlink_log_info(_mavlink_fd, "[ekf] ref: LA %.4f,LO %.4f,ALT %.2f", lat, lon, (double)gps_alt);

					#if 0
					warnx("HOME/REF: LA %8.4f,LO %8.4f,ALT %8.2f V: %8.4f %8.4f %8.4f", lat, lon, (double)gps_alt,
						(double)_ekf->velNED[0], (double)_ekf->velNED[1], (double)_ekf->velNED[2]);
					warnx("BARO: %8.4f m / ref: %8.4f m / gps offs: %8.4f m", (double)_ekf->baroHgt, (double)_baro_ref, (double)_baro_ref_offset);
					warnx("GPS: eph: %8.4f, epv: %8.4f, declination: %8.4f", (double)_gps.eph, (double)_gps.epv, (double)math::degrees(declination));
					#endif

					_gps_initialized = true;

				} else if (!_ekf->statesInitialised) {

					initVelNED[0] = 0.0f;
					initVelNED[1] = 0.0f;
					initVelNED[2] = 0.0f;
					_ekf->posNE[0] = posNED[0];
					_ekf->posNE[1] = posNED[1];

					_local_pos.ref_alt = _baro_ref;
					_baro_ref_offset = 0.0f;
					_baro_gps_offset = 0.0f;

					_ekf->InitialiseFilter(initVelNED, 0.0, 0.0, 0.0f, 0.0f);
				} else if (_ekf->statesInitialised) {

					// We're apparently initialized in this case now

					int check = check_filter_state();

					if (check) {
						// Let the system re-initialize itself
						continue;
					}


					// Run the strapdown INS equations every IMU update
					_ekf->UpdateStrapdownEquationsNED();
	#if 0
					// debug code - could be tunred into a filter mnitoring/watchdog function
					float tempQuat[4];

					for (uint8_t j = 0; j <= 3; j++) tempQuat[j] = states[j];

					quat2eul(eulerEst, tempQuat);

					for (uint8_t j = 0; j <= 2; j++) eulerDif[j] = eulerEst[j] - ahrsEul[j];

					if (eulerDif[2] > pi) eulerDif[2] -= 2 * pi;

					if (eulerDif[2] < -pi) eulerDif[2] += 2 * pi;

	#endif
					// store the predicted states for subsequent use by measurement fusion
					_ekf->StoreStates(IMUmsec);
					// Check if on ground - status is used by covariance prediction
					_ekf->OnGroundCheck();
					// sum delta angles and time used by covariance prediction
					_ekf->summedDelAng = _ekf->summedDelAng + _ekf->correctedDelAng;
					_ekf->summedDelVel = _ekf->summedDelVel + _ekf->dVelIMU;
					dt += _ekf->dtIMU;

					// perform a covariance prediction if the total delta angle has exceeded the limit
					// or the time limit will be exceeded at the next IMU update
					if ((dt >= (_ekf->covTimeStepMax - _ekf->dtIMU)) || (_ekf->summedDelAng.length() > _ekf->covDelAngMax)) {
						_ekf->CovariancePrediction(dt);
						_ekf->summedDelAng.zero();
						_ekf->summedDelVel.zero();
						dt = 0.0f;
					}

					// Fuse GPS Measurements
					if (newDataGps && _gps_initialized) {
						// Convert GPS measurements to Pos NE, hgt and Vel NED

						float gps_dt = (_gps.timestamp_position - last_gps) / 1e6f;

						// Calculate acceleration predicted by GPS velocity change
						if (((fabsf(_ekf->velNED[0] - _gps.vel_n_m_s) > FLT_EPSILON) ||
							(fabsf(_ekf->velNED[1] - _gps.vel_e_m_s) > FLT_EPSILON) ||
							(fabsf(_ekf->velNED[2] - _gps.vel_d_m_s) > FLT_EPSILON)) && (gps_dt > 0.00001f)) {

							_ekf->accelGPSNED[0] = (_ekf->velNED[0] - _gps.vel_n_m_s) / gps_dt;
							_ekf->accelGPSNED[1] = (_ekf->velNED[1] - _gps.vel_e_m_s) / gps_dt;
							_ekf->accelGPSNED[2] = (_ekf->velNED[2] - _gps.vel_d_m_s) / gps_dt;
						}

						_ekf->velNED[0] = _gps.vel_n_m_s;
						_ekf->velNED[1] = _gps.vel_e_m_s;
						_ekf->velNED[2] = _gps.vel_d_m_s;
						_ekf->calcposNED(posNED, _ekf->gpsLat, _ekf->gpsLon, _ekf->gpsHgt, _ekf->latRef, _ekf->lonRef, _ekf->hgtRef);

						_ekf->posNE[0] = posNED[0];
						_ekf->posNE[1] = posNED[1];
						// set fusion flags
						_ekf->fuseVelData = true;
						_ekf->fusePosData = true;
						// recall states stored at time of measurement after adjusting for delays
						_ekf->RecallStates(_ekf->statesAtVelTime, (IMUmsec - _parameters.vel_delay_ms));
						_ekf->RecallStates(_ekf->statesAtPosTime, (IMUmsec - _parameters.pos_delay_ms));
						// run the fusion step
						_ekf->FuseVelposNED();

					} else if (_ekf->statesInitialised) {
						// Convert GPS measurements to Pos NE, hgt and Vel NED
						_ekf->velNED[0] = 0.0f;
						_ekf->velNED[1] = 0.0f;
						_ekf->velNED[2] = 0.0f;

						_ekf->posNE[0] = 0.0f;
						_ekf->posNE[1] = 0.0f;
						// set fusion flags
						_ekf->fuseVelData = true;
						_ekf->fusePosData = true;
						// recall states stored at time of measurement after adjusting for delays
						_ekf->RecallStates(_ekf->statesAtVelTime, (IMUmsec - _parameters.vel_delay_ms));
						_ekf->RecallStates(_ekf->statesAtPosTime, (IMUmsec - _parameters.pos_delay_ms));
						// run the fusion step
						_ekf->FuseVelposNED();

					} else {
						_ekf->fuseVelData = false;
						_ekf->fusePosData = false;
					}

					if (newHgtData && _ekf->statesInitialised) {
						// Could use a blend of GPS and baro alt data if desired
						_ekf->hgtMea = 1.0f * (_ekf->baroHgt - _baro_ref);
						_ekf->fuseHgtData = true;
						// recall states stored at time of measurement after adjusting for delays
						_ekf->RecallStates(_ekf->statesAtHgtTime, (IMUmsec - _parameters.height_delay_ms));
						// run the fusion step
						_ekf->FuseVelposNED();

					} else {
						_ekf->fuseHgtData = false;
					}

					// Fuse Magnetometer Measurements
					if (newDataMag && _ekf->statesInitialised) {
						_ekf->fuseMagData = true;
						_ekf->RecallStates(_ekf->statesAtMagMeasTime, (IMUmsec - _parameters.mag_delay_ms)); // Assume 50 msec avg delay for magnetometer data

						_ekf->magstate.obsIndex = 0;
						_ekf->FuseMagnetometer();
						_ekf->FuseMagnetometer();
						_ekf->FuseMagnetometer();

					} else {
						_ekf->fuseMagData = false;
					}

					// Fuse Airspeed Measurements
					if (newAdsData && _ekf->statesInitialised && _ekf->VtasMeas > 8.0f) {
						_ekf->fuseVtasData = true;
						_ekf->RecallStates(_ekf->statesAtVtasMeasTime, (IMUmsec - _parameters.tas_delay_ms)); // assume 100 msec avg delay for airspeed data
						_ekf->FuseAirspeed();

					} else {
						_ekf->fuseVtasData = false;
					}


					// Output results
					math::Quaternion q(_ekf->states[0], _ekf->states[1], _ekf->states[2], _ekf->states[3]);
					math::Matrix<3, 3> R = q.to_dcm();
					math::Vector<3> euler = R.to_euler();

					for (int i = 0; i < 3; i++) for (int j = 0; j < 3; j++)
							_att.R[i][j] = R(i, j);

					_att.timestamp = _last_sensor_timestamp;
					_att.q[0] = _ekf->states[0];
					_att.q[1] = _ekf->states[1];
					_att.q[2] = _ekf->states[2];
					_att.q[3] = _ekf->states[3];
					_att.q_valid = true;
					_att.R_valid = true;

					_att.timestamp = _last_sensor_timestamp;
					_att.roll = euler(0);
					_att.pitch = euler(1);
					_att.yaw = euler(2);

					_att.rollspeed = _ekf->angRate.x - _ekf->states[10];
					_att.pitchspeed = _ekf->angRate.y - _ekf->states[11];
					_att.yawspeed = _ekf->angRate.z - _ekf->states[12];
					// gyro offsets
					_att.rate_offsets[0] = _ekf->states[10];
					_att.rate_offsets[1] = _ekf->states[11];
					_att.rate_offsets[2] = _ekf->states[12];

					/* lazily publish the attitude only once available */
					if (_att_pub > 0) {
						/* publish the attitude setpoint */
						orb_publish(ORB_ID(vehicle_attitude), _att_pub, &_att);

					} else {
						/* advertise and publish */
						_att_pub = orb_advertise(ORB_ID(vehicle_attitude), &_att);
					}

					if (_gps_initialized) {
						_local_pos.timestamp = _last_sensor_timestamp;
						_local_pos.x = _ekf->states[7];
						_local_pos.y = _ekf->states[8];
						// XXX need to announce change of Z reference somehow elegantly
						_local_pos.z = _ekf->states[9] - _baro_ref_offset;

						_local_pos.vx = _ekf->states[4];
						_local_pos.vy = _ekf->states[5];
						_local_pos.vz = _ekf->states[6];

						_local_pos.xy_valid = _gps_initialized;
						_local_pos.z_valid = true;
						_local_pos.v_xy_valid = _gps_initialized;
						_local_pos.v_z_valid = true;
						_local_pos.xy_global = true;

						_velocity_xy_filtered = 0.95f*_velocity_xy_filtered + 0.05f*sqrtf(_local_pos.vx*_local_pos.vx + _local_pos.vy*_local_pos.vy);
						_velocity_z_filtered = 0.95f*_velocity_z_filtered + 0.05f*fabsf(_local_pos.vz);
						_airspeed_filtered = 0.95f*_airspeed_filtered + + 0.05f*_airspeed.true_airspeed_m_s;


						/* crude land detector for fixedwing only,
						* TODO: adapt so that it works for both, maybe move to another location
						*/
						if (_velocity_xy_filtered < 5
							&& _velocity_z_filtered < 10
							&& _airspeed_filtered < 10) {
							_local_pos.landed = true;
						} else {
							_local_pos.landed = false;
						}

						_local_pos.z_global = false;
						_local_pos.yaw = _att.yaw;

						/* lazily publish the local position only once available */
						if (_local_pos_pub > 0) {
							/* publish the attitude setpoint */
							orb_publish(ORB_ID(vehicle_local_position), _local_pos_pub, &_local_pos);

						} else {
							/* advertise and publish */
							_local_pos_pub = orb_advertise(ORB_ID(vehicle_local_position), &_local_pos);
						}

						_global_pos.timestamp = _local_pos.timestamp;

						if (_local_pos.xy_global) {
							double est_lat, est_lon;
							map_projection_reproject(&_pos_ref, _local_pos.x, _local_pos.y, &est_lat, &est_lon);
							_global_pos.lat = est_lat;
							_global_pos.lon = est_lon;
							_global_pos.time_gps_usec = _gps.time_gps_usec;
							_global_pos.eph = _gps.eph;
							_global_pos.epv = _gps.epv;
						}

						if (_local_pos.v_xy_valid) {
							_global_pos.vel_n = _local_pos.vx;
							_global_pos.vel_e = _local_pos.vy;
						} else {
							_global_pos.vel_n = 0.0f;
							_global_pos.vel_e = 0.0f;
						}

						/* local pos alt is negative, change sign and add alt offsets */
						_global_pos.alt = _baro_ref + (-_local_pos.z) - _baro_gps_offset;

						if (_local_pos.v_z_valid) {
							_global_pos.vel_d = _local_pos.vz;
						}


						_global_pos.yaw = _local_pos.yaw;

						_global_pos.eph = _gps.eph;
						_global_pos.epv = _gps.epv;

						_global_pos.timestamp = _local_pos.timestamp;

						/* lazily publish the global position only once available */
						if (_global_pos_pub > 0) {
							/* publish the global position */
							orb_publish(ORB_ID(vehicle_global_position), _global_pos_pub, &_global_pos);

						} else {
							/* advertise and publish */
							_global_pos_pub = orb_advertise(ORB_ID(vehicle_global_position), &_global_pos);
						}

						if (hrt_elapsed_time(&_wind.timestamp) > 99000) {
							_wind.timestamp = _global_pos.timestamp;
							_wind.windspeed_north = _ekf->states[14];
							_wind.windspeed_east = _ekf->states[15];
							_wind.covariance_north = 0.0f; // XXX get form filter
							_wind.covariance_east = 0.0f;

							/* lazily publish the wind estimate only once available */
							if (_wind_pub > 0) {
								/* publish the wind estimate */
								orb_publish(ORB_ID(wind_estimate), _wind_pub, &_wind);

							} else {
								/* advertise and publish */
								_wind_pub = orb_advertise(ORB_ID(wind_estimate), &_wind);
							}

						}

					}

				}

				if (hrt_elapsed_time(&_wind.timestamp) > 99000) {
					_wind.timestamp = _global_pos.timestamp;
					_wind.windspeed_north = _ekf->states[14];
					_wind.windspeed_east = _ekf->states[15];
					_wind.covariance_north = _ekf->P[14][14];
					_wind.covariance_east = _ekf->P[15][15];

					/* lazily publish the wind estimate only once available */
					if (_wind_pub > 0) {
						/* publish the wind estimate */
						orb_publish(ORB_ID(wind_estimate), _wind_pub, &_wind);

					} else {
						/* advertise and publish */
						_wind_pub = orb_advertise(ORB_ID(wind_estimate), &_wind);
					}
				}
			}

		}

		perf_end(_loop_perf);
	}

	warnx("exiting.\n");

	_estimator_task = -1;
	_exit(0);
}

int
FixedwingEstimator::start()
{
	ASSERT(_estimator_task == -1);

	/* start the task */
	_estimator_task = task_spawn_cmd("ekf_att_pos_estimator",
					 SCHED_DEFAULT,
					 SCHED_PRIORITY_MAX - 40,
					 5000,
					 (main_t)&FixedwingEstimator::task_main_trampoline,
					 nullptr);

	if (_estimator_task < 0) {
		warn("task start failed");
		return -errno;
	}

	return OK;
}

void
FixedwingEstimator::print_status()
{
	math::Quaternion q(_ekf->states[0], _ekf->states[1], _ekf->states[2], _ekf->states[3]);
	math::Matrix<3, 3> R = q.to_dcm();
	math::Vector<3> euler = R.to_euler();

	printf("attitude: roll: %8.4f, pitch %8.4f, yaw: %8.4f degrees\n",
	       (double)math::degrees(euler(0)), (double)math::degrees(euler(1)), (double)math::degrees(euler(2)));

	// State vector:
	// 0-3: quaternions (q0, q1, q2, q3)
	// 4-6: Velocity - m/sec (North, East, Down)
	// 7-9: Position - m (North, East, Down)
	// 10-12: Delta Angle bias - rad (X,Y,Z)
	// 13:    Accelerometer offset
	// 14-15: Wind Vector  - m/sec (North,East)
	// 16-18: Earth Magnetic Field Vector - gauss (North, East, Down)
	// 19-21: Body Magnetic Field Vector - gauss (X,Y,Z)

	printf("dtIMU: %8.6f IMUmsec: %d\n", (double)_ekf->dtIMU, (int)IMUmsec);
	printf("baro alt: %8.4f GPS alt: %8.4f\n", (double)_baro.altitude, (double)(_gps.alt / 1e3f));
	printf("ref alt: %8.4f baro ref offset: %8.4f baro GPS offset: %8.4f\n", (double)_baro_ref, (double)_baro_ref_offset, (double)_baro_gps_offset);
	printf("dvel: %8.6f %8.6f %8.6f accel: %8.6f %8.6f %8.6f\n", (double)_ekf->dVelIMU.x, (double)_ekf->dVelIMU.y, (double)_ekf->dVelIMU.z, (double)_ekf->accel.x, (double)_ekf->accel.y, (double)_ekf->accel.z);
	printf("dang: %8.4f %8.4f %8.4f dang corr: %8.4f %8.4f %8.4f\n" , (double)_ekf->dAngIMU.x, (double)_ekf->dAngIMU.y, (double)_ekf->dAngIMU.z, (double)_ekf->correctedDelAng.x, (double)_ekf->correctedDelAng.y, (double)_ekf->correctedDelAng.z);
	printf("states (quat)        [0-3]: %8.4f, %8.4f, %8.4f, %8.4f\n", (double)_ekf->states[0], (double)_ekf->states[1], (double)_ekf->states[2], (double)_ekf->states[3]);
	printf("states (vel m/s)     [4-6]: %8.4f, %8.4f, %8.4f\n", (double)_ekf->states[4], (double)_ekf->states[5], (double)_ekf->states[6]);
	printf("states (pos m)      [7-9]: %8.4f, %8.4f, %8.4f\n", (double)_ekf->states[7], (double)_ekf->states[8], (double)_ekf->states[9]);
	printf("states (delta ang) [10-12]: %8.4f, %8.4f, %8.4f\n", (double)_ekf->states[10], (double)_ekf->states[11], (double)_ekf->states[12]);

	if (n_states == 23) {
		printf("states (accel offs)   [13]: %8.4f\n", (double)_ekf->states[13]);
		printf("states (wind)      [14-15]: %8.4f, %8.4f\n", (double)_ekf->states[14], (double)_ekf->states[15]);
		printf("states (earth mag) [16-18]: %8.4f, %8.4f, %8.4f\n", (double)_ekf->states[16], (double)_ekf->states[17], (double)_ekf->states[18]);
		printf("states (body mag)  [19-21]: %8.4f, %8.4f, %8.4f\n", (double)_ekf->states[19], (double)_ekf->states[20], (double)_ekf->states[21]);
		printf("states (terrain)      [22]: %8.4f\n", (double)_ekf->states[22]);

	} else {
		printf("states (wind)      [13-14]: %8.4f, %8.4f\n", (double)_ekf->states[13], (double)_ekf->states[14]);
		printf("states (earth mag) [15-17]: %8.4f, %8.4f, %8.4f\n", (double)_ekf->states[15], (double)_ekf->states[16], (double)_ekf->states[17]);
		printf("states (body mag)  [18-20]: %8.4f, %8.4f, %8.4f\n", (double)_ekf->states[18], (double)_ekf->states[19], (double)_ekf->states[20]);
	}
	printf("states: %s %s %s %s %s %s %s %s %s %s\n",
		       (_ekf->statesInitialised) ? "INITIALIZED" : "NON_INIT",
		       (_ekf->onGround) ? "ON_GROUND" : "AIRBORNE",
		       (_ekf->fuseVelData) ? "FUSE_VEL" : "INH_VEL",
		       (_ekf->fusePosData) ? "FUSE_POS" : "INH_POS",
		       (_ekf->fuseHgtData) ? "FUSE_HGT" : "INH_HGT",
		       (_ekf->fuseMagData) ? "FUSE_MAG" : "INH_MAG",
		       (_ekf->fuseVtasData) ? "FUSE_VTAS" : "INH_VTAS",
		       (_ekf->useAirspeed) ? "USE_AIRSPD" : "IGN_AIRSPD",
		       (_ekf->useCompass) ? "USE_COMPASS" : "IGN_COMPASS",
		       (_ekf->staticMode) ? "STATIC_MODE" : "DYNAMIC_MODE");
}

int FixedwingEstimator::trip_nan() {

	int ret = 0;

	// If system is not armed, inject a NaN value into the filter
	int armed_sub = orb_subscribe(ORB_ID(actuator_armed));

	struct actuator_armed_s armed;
	orb_copy(ORB_ID(actuator_armed), armed_sub, &armed);

	if (armed.armed) {
		warnx("ACTUATORS ARMED! NOT TRIPPING SYSTEM");
		ret = 1;
	} else {

		float nan_val = 0.0f / 0.0f;

		warnx("system not armed, tripping state vector with NaN values");
		_ekf->states[5] = nan_val;
		usleep(100000);

		warnx("tripping covariance #1 with NaN values");
		_ekf->KH[2][2] = nan_val; //  intermediate result used for covariance updates
		usleep(100000);

		warnx("tripping covariance #2 with NaN values");
		_ekf->KHP[5][5] = nan_val; // intermediate result used for covariance updates
		usleep(100000);

		warnx("tripping covariance #3 with NaN values");
		_ekf->P[3][3] = nan_val; // covariance matrix
		usleep(100000);

		warnx("tripping Kalman gains with NaN values");
		_ekf->Kfusion[0] = nan_val; // Kalman gains
		usleep(100000);

		warnx("tripping stored states[0] with NaN values");
		_ekf->storedStates[0][0] = nan_val;
		usleep(100000);

		warnx("\nDONE - FILTER STATE:");
		print_status();
	}

	close(armed_sub);
	return ret;
}

int ekf_att_pos_estimator_main(int argc, char *argv[])
{
	if (argc < 1)
		errx(1, "usage: ekf_att_pos_estimator {start|stop|status|logging}");

	if (!strcmp(argv[1], "start")) {

		if (estimator::g_estimator != nullptr)
			errx(1, "already running");

		estimator::g_estimator = new FixedwingEstimator;

		if (estimator::g_estimator == nullptr)
			errx(1, "alloc failed");

		if (OK != estimator::g_estimator->start()) {
			delete estimator::g_estimator;
			estimator::g_estimator = nullptr;
			err(1, "start failed");
		}

		exit(0);
	}

	if (!strcmp(argv[1], "stop")) {
		if (estimator::g_estimator == nullptr)
			errx(1, "not running");

		delete estimator::g_estimator;
		estimator::g_estimator = nullptr;
		exit(0);
	}

	if (!strcmp(argv[1], "status")) {
		if (estimator::g_estimator) {
			warnx("running");

			estimator::g_estimator->print_status();

			exit(0);

		} else {
			errx(1, "not running");
		}
	}

	if (!strcmp(argv[1], "trip")) {
		if (estimator::g_estimator) {
			int ret = estimator::g_estimator->trip_nan();

			exit(ret);

		} else {
			errx(1, "not running");
		}
	}

	if (!strcmp(argv[1], "logging")) {
		if (estimator::g_estimator) {
			int ret = estimator::g_estimator->enable_logging(true);

			exit(ret);

		} else {
			errx(1, "not running");
		}
	}

	if (!strcmp(argv[1], "debug")) {
		if (estimator::g_estimator) {
			int debug = strtoul(argv[2], NULL, 10);
			int ret = estimator::g_estimator->set_debuglevel(debug);

			exit(ret);

		} else {
			errx(1, "not running");
		}
	}

	warnx("unrecognized command");
	return 1;
}