Beispiel #1
0
void Ekf2::task_main()
{
	// subscribe to relevant topics
	_sensors_sub = orb_subscribe(ORB_ID(sensor_combined));
	_gps_sub = orb_subscribe(ORB_ID(vehicle_gps_position));
	_airspeed_sub = orb_subscribe(ORB_ID(airspeed));
	_params_sub = orb_subscribe(ORB_ID(parameter_update));
	_control_mode_sub = orb_subscribe(ORB_ID(vehicle_control_mode));
	_vehicle_status_sub = orb_subscribe(ORB_ID(vehicle_status));

	px4_pollfd_struct_t fds[2] = {};
	fds[0].fd = _sensors_sub;
	fds[0].events = POLLIN;
	fds[1].fd = _params_sub;
	fds[1].events = POLLIN;

	// initialise parameter cache
	updateParams();

	vehicle_gps_position_s gps = {};

	while (!_task_should_exit) {
		int ret = px4_poll(fds, sizeof(fds) / sizeof(fds[0]), 1000);

		if (ret < 0) {
			// Poll error, sleep and try again
			usleep(10000);
			continue;

		} else if (ret == 0) {
			// Poll timeout or no new data, do nothing
			continue;
		}

		if (fds[1].revents & POLLIN) {
			// read from param to clear updated flag
			struct parameter_update_s update;
			orb_copy(ORB_ID(parameter_update), _params_sub, &update);
			updateParams();

			// fetch sensor data in next loop
			continue;

		} else if (!(fds[0].revents & POLLIN)) {
			// no new data
			continue;
		}

		bool gps_updated = false;
		bool airspeed_updated = false;
		bool control_mode_updated = false;
		bool vehicle_status_updated = false;

		sensor_combined_s sensors = {};
		airspeed_s airspeed = {};
		vehicle_control_mode_s vehicle_control_mode = {};

		orb_copy(ORB_ID(sensor_combined), _sensors_sub, &sensors);

		// update all other topics if they have new data
		orb_check(_gps_sub, &gps_updated);

		if (gps_updated) {
			orb_copy(ORB_ID(vehicle_gps_position), _gps_sub, &gps);
		}

		orb_check(_airspeed_sub, &airspeed_updated);

		if (airspeed_updated) {
			orb_copy(ORB_ID(airspeed), _airspeed_sub, &airspeed);
		}

		// Use the control model data to determine if the motors are armed as a surrogate for an on-ground vs in-air status
		// TODO implement a global vehicle on-ground/in-air check
		orb_check(_control_mode_sub, &control_mode_updated);

		if (control_mode_updated) {
			orb_copy(ORB_ID(vehicle_control_mode), _control_mode_sub, &vehicle_control_mode);
			_ekf->set_arm_status(vehicle_control_mode.flag_armed);
		}

		hrt_abstime now = hrt_absolute_time();
		// push imu data into estimator
		_ekf->setIMUData(now, sensors.gyro_integral_dt[0], sensors.accelerometer_integral_dt[0],
				 &sensors.gyro_integral_rad[0], &sensors.accelerometer_integral_m_s[0]);

		// read mag data
		_ekf->setMagData(sensors.magnetometer_timestamp[0], &sensors.magnetometer_ga[0]);

		// read baro data
		_ekf->setBaroData(sensors.baro_timestamp[0], &sensors.baro_alt_meter[0]);

		// read gps data if available
		if (gps_updated) {
			struct gps_message gps_msg = {};
			gps_msg.time_usec = gps.timestamp_position;
			gps_msg.lat = gps.lat;
			gps_msg.lon = gps.lon;
			gps_msg.alt = gps.alt;
			gps_msg.fix_type = gps.fix_type;
			gps_msg.eph = gps.eph;
			gps_msg.epv = gps.epv;
			gps_msg.sacc = gps.s_variance_m_s;
			gps_msg.time_usec_vel = gps.timestamp_velocity;
			gps_msg.vel_m_s = gps.vel_m_s;
			gps_msg.vel_ned[0] = gps.vel_n_m_s;
			gps_msg.vel_ned[1] = gps.vel_e_m_s;
			gps_msg.vel_ned[2] = gps.vel_d_m_s;
			gps_msg.vel_ned_valid = gps.vel_ned_valid;
			gps_msg.nsats = gps.satellites_used;
			//TODO add gdop to gps topic
			gps_msg.gdop = 0.0f;

			_ekf->setGpsData(gps.timestamp_position, &gps_msg);
		}

		// read airspeed data if available
		if (airspeed_updated) {
			_ekf->setAirspeedData(airspeed.timestamp, &airspeed.indicated_airspeed_m_s);
		}

		// read vehicle status if available for 'landed' information
		orb_check(_vehicle_status_sub, &vehicle_status_updated);

		if (vehicle_status_updated) {
			struct vehicle_status_s status = {};
			orb_copy(ORB_ID(vehicle_status), _vehicle_status_sub, &status);
			_ekf->set_in_air_status(!status.condition_landed);
		}

		// run the EKF update
		_ekf->update();

		// generate vehicle attitude data
		struct vehicle_attitude_s att = {};
		att.timestamp = hrt_absolute_time();

		_ekf->copy_quaternion(att.q);
		matrix::Quaternion<float> q(att.q[0], att.q[1], att.q[2], att.q[3]);
		matrix::Euler<float> euler(q);
		att.roll = euler(0);
		att.pitch = euler(1);
		att.yaw = euler(2);

		// generate vehicle local position data
		struct vehicle_local_position_s lpos = {};
		float pos[3] = {};
		float vel[3] = {};

		lpos.timestamp = hrt_absolute_time();

		// Position in local NED frame
		_ekf->copy_position(pos);
		lpos.x = pos[0];
		lpos.y = pos[1];
		lpos.z = pos[2];

		// Velocity in NED frame (m/s)
		_ekf->copy_velocity(vel);
		lpos.vx = vel[0];
		lpos.vy = vel[1];
		lpos.vz = vel[2];

		// TODO: better status reporting
		lpos.xy_valid = _ekf->position_is_valid();
		lpos.z_valid = true;
		lpos.v_xy_valid = _ekf->position_is_valid();
		lpos.v_z_valid = true;

		// Position of local NED origin in GPS / WGS84 frame
		struct map_projection_reference_s ekf_origin = {};
		_ekf->get_ekf_origin(&lpos.ref_timestamp, &ekf_origin, &lpos.ref_alt);
		lpos.xy_global =
			_ekf->position_is_valid();          // true if position (x, y) is valid and has valid global reference (ref_lat, ref_lon)
		lpos.z_global = true;                                // true if z is valid and has valid global reference (ref_alt)
		lpos.ref_lat = ekf_origin.lat_rad * 180.0 / M_PI; // Reference point latitude in degrees
		lpos.ref_lon = ekf_origin.lon_rad * 180.0 / M_PI; // Reference point longitude in degrees

		// The rotation of the tangent plane vs. geographical north
		lpos.yaw = 0.0f;

		lpos.dist_bottom = 0.0f; // Distance to bottom surface (ground) in meters
		lpos.dist_bottom_rate = 0.0f; // Distance to bottom surface (ground) change rate
		lpos.surface_bottom_timestamp	= 0; // Time when new bottom surface found
		lpos.dist_bottom_valid = false; // true if distance to bottom surface is valid

		// TODO: uORB definition does not define what thes variables are. We have assumed them to be horizontal and vertical 1-std dev accuracy in metres
		// TODO: Should use sqrt of filter position variances
		lpos.eph = gps.eph;
		lpos.epv = gps.epv;

		// publish vehicle local position data
		if (_lpos_pub == nullptr) {
			_lpos_pub = orb_advertise(ORB_ID(vehicle_local_position), &lpos);

		} else {
			orb_publish(ORB_ID(vehicle_local_position), _lpos_pub, &lpos);
		}

		// generate control state data
		control_state_s ctrl_state = {};
		ctrl_state.timestamp = hrt_absolute_time();
		ctrl_state.roll_rate = _lp_roll_rate.apply(sensors.gyro_rad_s[0]);
		ctrl_state.pitch_rate = _lp_pitch_rate.apply(sensors.gyro_rad_s[1]);
		ctrl_state.yaw_rate = _lp_yaw_rate.apply(sensors.gyro_rad_s[2]);

		ctrl_state.q[0] = q(0);
		ctrl_state.q[1] = q(1);
		ctrl_state.q[2] = q(2);
		ctrl_state.q[3] = q(3);

		// publish control state data
		if (_control_state_pub == nullptr) {
			_control_state_pub = orb_advertise(ORB_ID(control_state), &ctrl_state);

		} else {
			orb_publish(ORB_ID(control_state), _control_state_pub, &ctrl_state);
		}

		// generate vehicle attitude data
		att.q[0] = q(0);
		att.q[1] = q(1);
		att.q[2] = q(2);
		att.q[3] = q(3);
		att.q_valid = true;

		att.rollspeed = sensors.gyro_rad_s[0];
		att.pitchspeed = sensors.gyro_rad_s[1];
		att.yawspeed = sensors.gyro_rad_s[2];

		// publish vehicle attitude data
		if (_att_pub == nullptr) {
			_att_pub = orb_advertise(ORB_ID(vehicle_attitude), &att);

		} else {
			orb_publish(ORB_ID(vehicle_attitude), _att_pub, &att);
		}

		// generate and publish global position data
		struct vehicle_global_position_s global_pos = {};

		if (_ekf->position_is_valid()) {
			// TODO: local origin is currenlty at GPS height origin - this is different to ekf_att_pos_estimator

			global_pos.timestamp = hrt_absolute_time(); // Time of this estimate, in microseconds since system start
			global_pos.time_utc_usec = gps.time_utc_usec; // GPS UTC timestamp in microseconds

			double est_lat, est_lon;
			map_projection_reproject(&ekf_origin, lpos.x, lpos.y, &est_lat, &est_lon);
			global_pos.lat = est_lat; // Latitude in degrees
			global_pos.lon = est_lon; // Longitude in degrees

			global_pos.alt = -pos[2] + lpos.ref_alt; // Altitude AMSL in meters

			global_pos.vel_n = vel[0]; // Ground north velocity, m/s
			global_pos.vel_e = vel[1]; // Ground east velocity, m/s
			global_pos.vel_d = vel[2]; // Ground downside velocity, m/s

			global_pos.yaw = euler(2); // Yaw in radians -PI..+PI.

			global_pos.eph = gps.eph; // Standard deviation of position estimate horizontally
			global_pos.epv = gps.epv; // Standard deviation of position vertically

			// TODO: implement terrain estimator
			global_pos.terrain_alt = 0.0f; // Terrain altitude in m, WGS84
			global_pos.terrain_alt_valid = false; // Terrain altitude estimate is valid
			// TODO use innovatun consistency check timouts to set this
			global_pos.dead_reckoning = false; // True if this position is estimated through dead-reckoning

			global_pos.pressure_alt = sensors.baro_alt_meter[0]; // Pressure altitude AMSL (m)

			if (_vehicle_global_position_pub == nullptr) {
				_vehicle_global_position_pub = orb_advertise(ORB_ID(vehicle_global_position), &global_pos);

			} else {
				orb_publish(ORB_ID(vehicle_global_position), _vehicle_global_position_pub, &global_pos);
			}
		}

		// publish estimator status
		struct estimator_status_s status = {};
		status.timestamp = hrt_absolute_time();
		_ekf->get_state_delayed(status.states);
		_ekf->get_covariances(status.covariances);
		//status.gps_check_fail_flags = _ekf->_gps_check_fail_status.value;

		if (_estimator_status_pub == nullptr) {
			_estimator_status_pub = orb_advertise(ORB_ID(estimator_status), &status);

		} else {
			orb_publish(ORB_ID(estimator_status), _estimator_status_pub, &status);
		}

		// publish estimator innovation data
		struct ekf2_innovations_s innovations = {};
		innovations.timestamp = hrt_absolute_time();
		_ekf->get_vel_pos_innov(&innovations.vel_pos_innov[0]);
		_ekf->get_mag_innov(&innovations.mag_innov[0]);
		_ekf->get_heading_innov(&innovations.heading_innov);

		_ekf->get_vel_pos_innov_var(&innovations.vel_pos_innov_var[0]);
		_ekf->get_mag_innov_var(&innovations.mag_innov_var[0]);
		_ekf->get_heading_innov_var(&innovations.heading_innov_var);

		if (_estimator_innovations_pub == nullptr) {
			_estimator_innovations_pub = orb_advertise(ORB_ID(ekf2_innovations), &innovations);

		} else {
			orb_publish(ORB_ID(ekf2_innovations), _estimator_innovations_pub, &innovations);
		}

		// save the declination to the EKF2_MAG_DECL parameter when a dis-arm event is detected
		if ((_params->mag_declination_source & (1 << 1)) && _prev_motors_armed && !vehicle_control_mode.flag_armed) {
			float decl_deg;
			_ekf->copy_mag_decl_deg(&decl_deg);
			_mag_declination_deg->set(decl_deg);
		}

		_prev_motors_armed = vehicle_control_mode.flag_armed;

	}

	delete ekf2::instance;
	ekf2::instance = nullptr;
}
Beispiel #2
0
void Ekf2::task_main()
{
	// subscribe to relevant topics
	_sensors_sub = orb_subscribe(ORB_ID(sensor_combined));
	_gps_sub = orb_subscribe(ORB_ID(vehicle_gps_position));
	_airspeed_sub = orb_subscribe(ORB_ID(airspeed));
	_params_sub = orb_subscribe(ORB_ID(parameter_update));
	_optical_flow_sub = orb_subscribe(ORB_ID(optical_flow));
	_range_finder_sub = orb_subscribe(ORB_ID(distance_sensor));
	_vehicle_land_detected_sub = orb_subscribe(ORB_ID(vehicle_land_detected));

	px4_pollfd_struct_t fds[2] = {};
	fds[0].fd = _sensors_sub;
	fds[0].events = POLLIN;
	fds[1].fd = _params_sub;
	fds[1].events = POLLIN;

	// initialise parameter cache
	updateParams();

	// initialize data structures outside of loop
	// because they will else not always be
	// properly populated
	sensor_combined_s sensors = {};
	vehicle_gps_position_s gps = {};
	airspeed_s airspeed = {};
	optical_flow_s optical_flow = {};
	distance_sensor_s range_finder = {};
	vehicle_land_detected_s vehicle_land_detected = {};

	while (!_task_should_exit) {
		int ret = px4_poll(fds, sizeof(fds) / sizeof(fds[0]), 1000);

		if (ret < 0) {
			// Poll error, sleep and try again
			usleep(10000);
			continue;

		} else if (ret == 0) {
			// Poll timeout or no new data, do nothing
			continue;
		}

		if (fds[1].revents & POLLIN) {
			// read from param to clear updated flag
			struct parameter_update_s update;
			orb_copy(ORB_ID(parameter_update), _params_sub, &update);
			updateParams();

			// fetch sensor data in next loop
			continue;

		} else if (!(fds[0].revents & POLLIN)) {
			// no new data
			continue;
		}

		bool gps_updated = false;
		bool airspeed_updated = false;
		bool optical_flow_updated = false;
		bool range_finder_updated = false;
		bool vehicle_land_detected_updated = false;

		orb_copy(ORB_ID(sensor_combined), _sensors_sub, &sensors);
		// update all other topics if they have new data
		orb_check(_gps_sub, &gps_updated);

		if (gps_updated) {
			orb_copy(ORB_ID(vehicle_gps_position), _gps_sub, &gps);
		}

		orb_check(_airspeed_sub, &airspeed_updated);

		if (airspeed_updated) {
			orb_copy(ORB_ID(airspeed), _airspeed_sub, &airspeed);
		}

		orb_check(_optical_flow_sub, &optical_flow_updated);

		if (optical_flow_updated) {
			orb_copy(ORB_ID(optical_flow), _optical_flow_sub, &optical_flow);
		}

		orb_check(_range_finder_sub, &range_finder_updated);

		if (range_finder_updated) {
			orb_copy(ORB_ID(distance_sensor), _range_finder_sub, &range_finder);
		}

		// in replay mode we are getting the actual timestamp from the sensor topic
		hrt_abstime now = 0;

		if (_replay_mode) {
			now = sensors.timestamp;

		} else {
			now = hrt_absolute_time();
		}

		// push imu data into estimator
		_ekf.setIMUData(now, sensors.gyro_integral_dt[0], sensors.accelerometer_integral_dt[0],
				&sensors.gyro_integral_rad[0], &sensors.accelerometer_integral_m_s[0]);

		// read mag data
		_ekf.setMagData(sensors.magnetometer_timestamp[0], &sensors.magnetometer_ga[0]);

		// read baro data
		_ekf.setBaroData(sensors.baro_timestamp[0], &sensors.baro_alt_meter[0]);

		// read gps data if available
		if (gps_updated) {
			struct gps_message gps_msg = {};
			gps_msg.time_usec = gps.timestamp_position;
			gps_msg.lat = gps.lat;
			gps_msg.lon = gps.lon;
			gps_msg.alt = gps.alt;
			gps_msg.fix_type = gps.fix_type;
			gps_msg.eph = gps.eph;
			gps_msg.epv = gps.epv;
			gps_msg.sacc = gps.s_variance_m_s;
			gps_msg.time_usec_vel = gps.timestamp_velocity;
			gps_msg.vel_m_s = gps.vel_m_s;
			gps_msg.vel_ned[0] = gps.vel_n_m_s;
			gps_msg.vel_ned[1] = gps.vel_e_m_s;
			gps_msg.vel_ned[2] = gps.vel_d_m_s;
			gps_msg.vel_ned_valid = gps.vel_ned_valid;
			gps_msg.nsats = gps.satellites_used;
			//TODO add gdop to gps topic
			gps_msg.gdop = 0.0f;

			_ekf.setGpsData(gps.timestamp_position, &gps_msg);
		}

		// read airspeed data if available
		float eas2tas = airspeed.true_airspeed_m_s / airspeed.indicated_airspeed_m_s;

		if (airspeed_updated && airspeed.true_airspeed_m_s > 7.0f) {
			_ekf.setAirspeedData(airspeed.timestamp, &airspeed.true_airspeed_m_s, &eas2tas);
		}

		if (optical_flow_updated) {
			flow_message flow;
			flow.flowdata(0) = optical_flow.pixel_flow_x_integral;
			flow.flowdata(1) = optical_flow.pixel_flow_y_integral;
			flow.quality = optical_flow.quality;
			flow.gyrodata(0) = optical_flow.gyro_x_rate_integral;
			flow.gyrodata(1) = optical_flow.gyro_y_rate_integral;
			flow.gyrodata(2) = optical_flow.gyro_z_rate_integral;
			flow.dt = optical_flow.integration_timespan;

			if (PX4_ISFINITE(optical_flow.pixel_flow_y_integral) &&
			    PX4_ISFINITE(optical_flow.pixel_flow_x_integral)) {
				_ekf.setOpticalFlowData(optical_flow.timestamp, &flow);
			}
		}

		if (range_finder_updated) {
			_ekf.setRangeData(range_finder.timestamp, &range_finder.current_distance);
		}

		orb_check(_vehicle_land_detected_sub, &vehicle_land_detected_updated);

		if (vehicle_land_detected_updated) {
			orb_copy(ORB_ID(vehicle_land_detected), _vehicle_land_detected_sub, &vehicle_land_detected);
			_ekf.set_in_air_status(!vehicle_land_detected.landed);
		}

		// run the EKF update and output
		if (_ekf.update()) {
			// generate vehicle attitude quaternion data
			struct vehicle_attitude_s att = {};
			_ekf.copy_quaternion(att.q);
			matrix::Quaternion<float> q(att.q[0], att.q[1], att.q[2], att.q[3]);

			// generate control state data
			control_state_s ctrl_state = {};
			ctrl_state.timestamp = hrt_absolute_time();
			ctrl_state.roll_rate = _lp_roll_rate.apply(sensors.gyro_rad_s[0]);
			ctrl_state.pitch_rate = _lp_pitch_rate.apply(sensors.gyro_rad_s[1]);
			ctrl_state.yaw_rate = _lp_yaw_rate.apply(sensors.gyro_rad_s[2]);

			// Velocity in body frame
			float velocity[3];
			_ekf.get_velocity(velocity);
			Vector3f v_n(velocity);
			matrix::Dcm<float> R_to_body(q.inversed());
			Vector3f v_b = R_to_body * v_n;
			ctrl_state.x_vel = v_b(0);
			ctrl_state.y_vel = v_b(1);
			ctrl_state.z_vel = v_b(2);


			// Local Position NED
			float position[3];
			_ekf.get_position(position);
			ctrl_state.x_pos = position[0];
			ctrl_state.y_pos = position[1];
			ctrl_state.z_pos = position[2];

			// Attitude quaternion
			ctrl_state.q[0] = q(0);
			ctrl_state.q[1] = q(1);
			ctrl_state.q[2] = q(2);
			ctrl_state.q[3] = q(3);

			// Acceleration data
			matrix::Vector<float, 3> acceleration = {&sensors.accelerometer_m_s2[0]};

			float accel_bias[3];
			_ekf.get_accel_bias(accel_bias);
			ctrl_state.x_acc = acceleration(0) - accel_bias[0];
			ctrl_state.y_acc = acceleration(1) - accel_bias[1];
			ctrl_state.z_acc = acceleration(2) - accel_bias[2];

			// compute lowpass filtered horizontal acceleration
			acceleration = R_to_body.transpose() * acceleration;
			_acc_hor_filt = 0.95f * _acc_hor_filt + 0.05f * sqrtf(acceleration(0) * acceleration(0) + acceleration(
						1) * acceleration(1));
			ctrl_state.horz_acc_mag = _acc_hor_filt;

			// Airspeed - take airspeed measurement directly here as no wind is estimated
			if (PX4_ISFINITE(airspeed.indicated_airspeed_m_s) && hrt_absolute_time() - airspeed.timestamp < 1e6
			    && airspeed.timestamp > 0) {
				ctrl_state.airspeed = airspeed.indicated_airspeed_m_s;
				ctrl_state.airspeed_valid = true;

			} else {
				ctrl_state.airspeed_valid = false;
			}

			// publish control state data
			if (_control_state_pub == nullptr) {
				_control_state_pub = orb_advertise(ORB_ID(control_state), &ctrl_state);

			} else {
				orb_publish(ORB_ID(control_state), _control_state_pub, &ctrl_state);
			}


			// generate remaining vehicle attitude data
			att.timestamp = hrt_absolute_time();
			matrix::Euler<float> euler(q);
			att.roll = euler(0);
			att.pitch = euler(1);
			att.yaw = euler(2);

			att.q[0] = q(0);
			att.q[1] = q(1);
			att.q[2] = q(2);
			att.q[3] = q(3);
			att.q_valid = true;

			att.rollspeed = sensors.gyro_rad_s[0];
			att.pitchspeed = sensors.gyro_rad_s[1];
			att.yawspeed = sensors.gyro_rad_s[2];

			// publish vehicle attitude data
			if (_att_pub == nullptr) {
				_att_pub = orb_advertise(ORB_ID(vehicle_attitude), &att);

			} else {
				orb_publish(ORB_ID(vehicle_attitude), _att_pub, &att);
			}

			// generate vehicle local position data
			struct vehicle_local_position_s lpos = {};
			float pos[3] = {};
			float vel[3] = {};

			lpos.timestamp = hrt_absolute_time();

			// Position of body origin in local NED frame
			_ekf.get_position(pos);
			lpos.x = pos[0];
			lpos.y = pos[1];
			lpos.z = pos[2];

			// Velocity of body origin in local NED frame (m/s)
			_ekf.get_velocity(vel);
			lpos.vx = vel[0];
			lpos.vy = vel[1];
			lpos.vz = vel[2];

			// TODO: better status reporting
			lpos.xy_valid = _ekf.local_position_is_valid();
			lpos.z_valid = true;
			lpos.v_xy_valid = _ekf.local_position_is_valid();
			lpos.v_z_valid = true;

			// Position of local NED origin in GPS / WGS84 frame
			struct map_projection_reference_s ekf_origin = {};
			// true if position (x, y) is valid and has valid global reference (ref_lat, ref_lon)
			_ekf.get_ekf_origin(&lpos.ref_timestamp, &ekf_origin, &lpos.ref_alt);
			lpos.xy_global = _ekf.global_position_is_valid();
			lpos.z_global = true;                                // true if z is valid and has valid global reference (ref_alt)
			lpos.ref_lat = ekf_origin.lat_rad * 180.0 / M_PI; // Reference point latitude in degrees
			lpos.ref_lon = ekf_origin.lon_rad * 180.0 / M_PI; // Reference point longitude in degrees

			// The rotation of the tangent plane vs. geographical north
			lpos.yaw = att.yaw;

			float terrain_vpos;
			lpos.dist_bottom_valid = _ekf.get_terrain_vert_pos(&terrain_vpos);
			lpos.dist_bottom = terrain_vpos - pos[2]; // Distance to bottom surface (ground) in meters
			lpos.dist_bottom_rate = -vel[2]; // Distance to bottom surface (ground) change rate
			lpos.surface_bottom_timestamp	= hrt_absolute_time(); // Time when new bottom surface found

			// TODO: uORB definition does not define what these variables are. We have assumed them to be horizontal and vertical 1-std dev accuracy in metres
			Vector3f pos_var, vel_var;
			_ekf.get_pos_var(pos_var);
			_ekf.get_vel_var(vel_var);
			lpos.eph = sqrt(pos_var(0) + pos_var(1));
			lpos.epv = sqrt(pos_var(2));

			// publish vehicle local position data
			if (_lpos_pub == nullptr) {
				_lpos_pub = orb_advertise(ORB_ID(vehicle_local_position), &lpos);

			} else {
				orb_publish(ORB_ID(vehicle_local_position), _lpos_pub, &lpos);
			}

			// generate and publish global position data
			struct vehicle_global_position_s global_pos = {};

			if (_ekf.global_position_is_valid()) {
				global_pos.timestamp = hrt_absolute_time(); // Time of this estimate, in microseconds since system start
				global_pos.time_utc_usec = gps.time_utc_usec; // GPS UTC timestamp in microseconds

				double est_lat, est_lon;
				map_projection_reproject(&ekf_origin, lpos.x, lpos.y, &est_lat, &est_lon);
				global_pos.lat = est_lat; // Latitude in degrees
				global_pos.lon = est_lon; // Longitude in degrees

				global_pos.alt = -pos[2] + lpos.ref_alt; // Altitude AMSL in meters

				global_pos.vel_n = vel[0]; // Ground north velocity, m/s
				global_pos.vel_e = vel[1]; // Ground east velocity, m/s
				global_pos.vel_d = vel[2]; // Ground downside velocity, m/s

				global_pos.yaw = euler(2); // Yaw in radians -PI..+PI.

				global_pos.eph = sqrt(pos_var(0) + pos_var(1));; // Standard deviation of position estimate horizontally
				global_pos.epv = sqrt(pos_var(2)); // Standard deviation of position vertically

				// TODO: implement terrain estimator
				global_pos.terrain_alt = 0.0f; // Terrain altitude in m, WGS84
				global_pos.terrain_alt_valid = false; // Terrain altitude estimate is valid
				// TODO use innovatun consistency check timouts to set this
				global_pos.dead_reckoning = false; // True if this position is estimated through dead-reckoning

				global_pos.pressure_alt = sensors.baro_alt_meter[0]; // Pressure altitude AMSL (m)

				if (_vehicle_global_position_pub == nullptr) {
					_vehicle_global_position_pub = orb_advertise(ORB_ID(vehicle_global_position), &global_pos);

				} else {
					orb_publish(ORB_ID(vehicle_global_position), _vehicle_global_position_pub, &global_pos);
				}
			}

		} else if (_replay_mode) {
			// in replay mode we have to tell the replay module not to wait for an update
			// we do this by publishing an attitude with zero timestamp
			struct vehicle_attitude_s att = {};
			att.timestamp = 0;

			if (_att_pub == nullptr) {
				_att_pub = orb_advertise(ORB_ID(vehicle_attitude), &att);

			} else {
				orb_publish(ORB_ID(vehicle_attitude), _att_pub, &att);
			}
		}

		// publish estimator status
		struct estimator_status_s status = {};
		status.timestamp = hrt_absolute_time();
		_ekf.get_state_delayed(status.states);
		_ekf.get_covariances(status.covariances);
		_ekf.get_gps_check_status(&status.gps_check_fail_flags);
		_ekf.get_control_mode(&status.control_mode_flags);
		_ekf.get_filter_fault_status(&status.filter_fault_flags);

		if (_estimator_status_pub == nullptr) {
			_estimator_status_pub = orb_advertise(ORB_ID(estimator_status), &status);

		} else {
			orb_publish(ORB_ID(estimator_status), _estimator_status_pub, &status);
		}

		// Publish wind estimate
		struct wind_estimate_s wind_estimate = {};
		wind_estimate.timestamp = hrt_absolute_time();
		wind_estimate.windspeed_north = status.states[22];
		wind_estimate.windspeed_east = status.states[23];
		wind_estimate.covariance_north = status.covariances[22];
		wind_estimate.covariance_east = status.covariances[23];

		if (_wind_pub == nullptr) {
			_wind_pub = orb_advertise(ORB_ID(wind_estimate), &wind_estimate);

		} else {
			orb_publish(ORB_ID(wind_estimate), _wind_pub, &wind_estimate);
		}

		// publish estimator innovation data
		struct ekf2_innovations_s innovations = {};
		innovations.timestamp = hrt_absolute_time();
		_ekf.get_vel_pos_innov(&innovations.vel_pos_innov[0]);
		_ekf.get_mag_innov(&innovations.mag_innov[0]);
		_ekf.get_heading_innov(&innovations.heading_innov);
		_ekf.get_airspeed_innov(&innovations.airspeed_innov);
		_ekf.get_flow_innov(&innovations.flow_innov[0]);
		_ekf.get_hagl_innov(&innovations.hagl_innov);

		_ekf.get_vel_pos_innov_var(&innovations.vel_pos_innov_var[0]);
		_ekf.get_mag_innov_var(&innovations.mag_innov_var[0]);
		_ekf.get_heading_innov_var(&innovations.heading_innov_var);
		_ekf.get_airspeed_innov_var(&innovations.airspeed_innov_var);
		_ekf.get_flow_innov_var(&innovations.flow_innov_var[0]);
		_ekf.get_hagl_innov_var(&innovations.hagl_innov_var);

		if (_estimator_innovations_pub == nullptr) {
			_estimator_innovations_pub = orb_advertise(ORB_ID(ekf2_innovations), &innovations);

		} else {
			orb_publish(ORB_ID(ekf2_innovations), _estimator_innovations_pub, &innovations);
		}

		// save the declination to the EKF2_MAG_DECL parameter when a land event is detected
		if ((_params->mag_declination_source & (1 << 1)) && !_prev_landed && vehicle_land_detected.landed) {
			float decl_deg;
			_ekf.copy_mag_decl_deg(&decl_deg);
			_mag_declination_deg.set(decl_deg);
		}
		_prev_landed = vehicle_land_detected.landed;

		// publish replay message if in replay mode
		bool publish_replay_message = (bool)_param_record_replay_msg.get();

		if (publish_replay_message) {
			struct ekf2_replay_s replay = {};
			replay.time_ref = now;
			replay.gyro_integral_dt = sensors.gyro_integral_dt[0];
			replay.accelerometer_integral_dt = sensors.accelerometer_integral_dt[0];
			replay.magnetometer_timestamp = sensors.magnetometer_timestamp[0];
			replay.baro_timestamp = sensors.baro_timestamp[0];
			memcpy(&replay.gyro_integral_rad[0], &sensors.gyro_integral_rad[0], sizeof(replay.gyro_integral_rad));
			memcpy(&replay.accelerometer_integral_m_s[0], &sensors.accelerometer_integral_m_s[0],
			       sizeof(replay.accelerometer_integral_m_s));
			memcpy(&replay.magnetometer_ga[0], &sensors.magnetometer_ga[0], sizeof(replay.magnetometer_ga));
			replay.baro_alt_meter = sensors.baro_alt_meter[0];

			// only write gps data if we had a gps update.
			if (gps_updated) {
				replay.time_usec = gps.timestamp_position;
				replay.time_usec_vel = gps.timestamp_velocity;
				replay.lat = gps.lat;
				replay.lon = gps.lon;
				replay.alt = gps.alt;
				replay.fix_type = gps.fix_type;
				replay.nsats = gps.satellites_used;
				replay.eph = gps.eph;
				replay.epv = gps.epv;
				replay.sacc = gps.s_variance_m_s;
				replay.vel_m_s = gps.vel_m_s;
				replay.vel_n_m_s = gps.vel_n_m_s;
				replay.vel_e_m_s = gps.vel_e_m_s;
				replay.vel_d_m_s = gps.vel_d_m_s;
				replay.vel_ned_valid = gps.vel_ned_valid;

			} else {
				// this will tell the logging app not to bother logging any gps replay data
				replay.time_usec = 0;
			}

			if (optical_flow_updated) {
				replay.flow_timestamp = optical_flow.timestamp;
				replay.flow_pixel_integral[0] = optical_flow.pixel_flow_x_integral;
				replay.flow_pixel_integral[1] = optical_flow.pixel_flow_y_integral;
				replay.flow_gyro_integral[0] = optical_flow.gyro_x_rate_integral;
				replay.flow_gyro_integral[1] = optical_flow.gyro_y_rate_integral;
				replay.flow_time_integral = optical_flow.integration_timespan;
				replay.flow_quality = optical_flow.quality;

			} else {
				replay.flow_timestamp = 0;
			}

			if (range_finder_updated) {
				replay.rng_timestamp = range_finder.timestamp;
				replay.range_to_ground = range_finder.current_distance;

			} else {
				replay.rng_timestamp = 0;
			}

			if (airspeed_updated) {
				replay.asp_timestamp = airspeed.timestamp;
				replay.indicated_airspeed_m_s = airspeed.indicated_airspeed_m_s;
				replay.true_airspeed_m_s = airspeed.true_airspeed_m_s;
				replay.true_airspeed_unfiltered_m_s = airspeed.true_airspeed_unfiltered_m_s;
				replay.air_temperature_celsius = airspeed.air_temperature_celsius;
				replay.confidence = airspeed.confidence;

			} else {
				replay.asp_timestamp = 0;
			}


			if (_replay_pub == nullptr) {
				_replay_pub = orb_advertise(ORB_ID(ekf2_replay), &replay);

			} else {
				orb_publish(ORB_ID(ekf2_replay), _replay_pub, &replay);
			}
		}
	}

	delete ekf2::instance;
	ekf2::instance = nullptr;
}