ekf2: prefer airspeed_validated over raw airspeed if available (#19159)

* ekf2: prefer airspeed_validated over raw airspeed if available

Co-authored-by: Silvan Fuhrer <silvan@auterion.com>

src/modules/ekf2/EKF2.cpp

@@ -1388,6 +1388,36 @@ float EKF2::filter_altitude_ellipsoid(float amsl_hgt)
 void EKF2::UpdateAirspeedSample(ekf2_timestamps_s &ekf2_timestamps)
 {
 	// EKF airspeed sample
+	// prefer ORB_ID(airspeed_validated) if available, otherwise fallback to raw airspeed ORB_ID(airspeed)
+	if (_airspeed_validated_sub.updated()) {
+		const unsigned last_generation = _airspeed_validated_sub.get_last_generation();
+		airspeed_validated_s airspeed_validated;
+
+		if (_airspeed_validated_sub.update(&airspeed_validated)) {
+			if (_msg_missed_airspeed_validated_perf == nullptr) {
+				_msg_missed_airspeed_validated_perf = perf_alloc(PC_COUNT, MODULE_NAME": airspeed validated messages missed");
+
+			} else if (_airspeed_validated_sub.get_last_generation() != last_generation + 1) {
+				perf_count(_msg_missed_airspeed_validated_perf);
+			}
+
+			if (PX4_ISFINITE(airspeed_validated.true_airspeed_m_s)
+			    && PX4_ISFINITE(airspeed_validated.calibrated_airspeed_m_s)
+			    && (airspeed_validated.calibrated_airspeed_m_s > 0.f)
+			   ) {
+				airspeedSample airspeed_sample {
+					.time_us = airspeed_validated.timestamp,
+					.true_airspeed = airspeed_validated.true_airspeed_m_s,
+					.eas2tas = airspeed_validated.true_airspeed_m_s / airspeed_validated.calibrated_airspeed_m_s,
+				};
+				_ekf.setAirspeedData(airspeed_sample);
+			}
+
+			_airspeed_validated_timestamp_last = airspeed_validated.timestamp;
+		}
+
+	} else if ((hrt_elapsed_time(&_airspeed_validated_timestamp_last) > 3_s) && _airspeed_sub.updated()) {
+		// use ORB_ID(airspeed) if ORB_ID(airspeed_validated) is unavailable
 		const unsigned last_generation = _airspeed_sub.get_last_generation();
 		airspeed_s airspeed;
 
@@ -1399,23 +1429,26 @@ void EKF2::UpdateAirspeedSample(ekf2_timestamps_s &ekf2_timestamps)
 				perf_count(_msg_missed_airspeed_perf);
 			}
 
-		// The airspeed measurement received via the airspeed.msg topic has not been corrected
-		// for scale favtor errors and requires the ASPD_SCALE correction to be applied.
-		// This could be avoided if true_airspeed_m_s from the airspeed-validated.msg topic
-		// was used instead, however this would introduce a potential circular dependency
-		// via the wind estimator that uses EKF velocity estimates.
+			// The airspeed measurement received via ORB_ID(airspeed) topic has not been corrected
+			// for scale factor errors and requires the ASPD_SCALE correction to be applied.
 			const float true_airspeed_m_s = airspeed.true_airspeed_m_s * _airspeed_scale_factor;
 
+			if (PX4_ISFINITE(airspeed.true_airspeed_m_s)
+			    && PX4_ISFINITE(airspeed.indicated_airspeed_m_s)
+			    && (airspeed.indicated_airspeed_m_s > 0.f)
+			   ) {
 				airspeedSample airspeed_sample {
 					.time_us = airspeed.timestamp,
 					.true_airspeed = true_airspeed_m_s,
 					.eas2tas = airspeed.true_airspeed_m_s / airspeed.indicated_airspeed_m_s,
 				};
 				_ekf.setAirspeedData(airspeed_sample);
+			}
 
 			ekf2_timestamps.airspeed_timestamp_rel = (int16_t)((int64_t)airspeed.timestamp / 100 -
 					(int64_t)ekf2_timestamps.timestamp / 100);
 		}
+	}
 }
 
 void EKF2::UpdateAuxVelSample(ekf2_timestamps_s &ekf2_timestamps)

src/modules/ekf2/EKF2.hpp

@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (c) 2015-2021 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2015-2022 PX4 Development Team. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -64,6 +64,7 @@
 #include <uORB/SubscriptionCallback.hpp>
 #include <uORB/SubscriptionMultiArray.hpp>
 #include <uORB/topics/airspeed.h>
+#include <uORB/topics/airspeed_validated.h>
 #include <uORB/topics/distance_sensor.h>
 #include <uORB/topics/ekf2_timestamps.h>
 #include <uORB/topics/ekf_gps_drift.h>
@@ -190,6 +191,7 @@ private:
 	perf_counter_t _msg_missed_imu_perf{perf_alloc(PC_COUNT, MODULE_NAME": IMU message missed")};
 	perf_counter_t _msg_missed_air_data_perf{nullptr};
 	perf_counter_t _msg_missed_airspeed_perf{nullptr};
+	perf_counter_t _msg_missed_airspeed_validated_perf{nullptr};
 	perf_counter_t _msg_missed_distance_sensor_perf{nullptr};
 	perf_counter_t _msg_missed_gps_perf{nullptr};
 	perf_counter_t _msg_missed_landing_target_pose_perf{nullptr};
@@ -240,11 +242,13 @@ private:
 	float _last_baro_bias_published{};
 
 	float _airspeed_scale_factor{1.0f}; ///< scale factor correction applied to airspeed measurements
+	hrt_abstime _airspeed_validated_timestamp_last{0};
 
 	uORB::SubscriptionInterval _parameter_update_sub{ORB_ID(parameter_update), 1_s};
 
 	uORB::Subscription _airdata_sub{ORB_ID(vehicle_air_data)};
 	uORB::Subscription _airspeed_sub{ORB_ID(airspeed)};
+	uORB::Subscription _airspeed_validated_sub{ORB_ID(airspeed_validated)};
 	uORB::Subscription _ev_odom_sub{ORB_ID(vehicle_visual_odometry)};
 	uORB::Subscription _landing_target_pose_sub{ORB_ID(landing_target_pose)};
 	uORB::Subscription _magnetometer_sub{ORB_ID(vehicle_magnetometer)};