Clean up temperature msg fields (#24272)

* remove temp field from airspeed.msg, adjust temp selection

* temp-sensor hirarchy: airspeed, ext. baro, default value

* directly use diff-press or baro temp in true-airspeed  calc

* improve clarity

* add enum for temperature source in VehicleAirData.msg

msg/Airspeed.msg

@@ -5,6 +5,4 @@ float32 indicated_airspeed_m_s   # indicated airspeed in m/s
 
 float32 true_airspeed_m_s        # true filtered airspeed in m/s
 
-float32 air_temperature_celsius  # air temperature in degrees Celsius, -1000 if unknown
-
 float32 confidence               # confidence value from 0 to 1 for this sensor

msg/VehicleAirData.msg

@@ -6,10 +6,10 @@ uint64 timestamp_sample     # the timestamp of the raw data (microseconds)
 uint32 baro_device_id       # unique device ID for the selected barometer
 
 float32 baro_alt_meter			# Altitude above MSL calculated from temperature compensated baro sensor data using an ISA corrected for sea level pressure SENS_BARO_QNH.
-float32 baro_temp_celcius		# Temperature in degrees Celsius
 float32 baro_pressure_pa		# Absolute pressure in Pascals
+float32 ambient_temperature		# Abient temperature in degrees Celsius
+uint8 temperature_source		# Source of temperature data: 0: Default Temperature (15°C), 1: External Baro, 2: Airspeed
 
 float32 rho				# air density
-float32 eas2tas         # equivalent airspeed to true airspeed conversion factor
 
 uint8 calibration_count     # Calibration changed counter. Monotonically increases whenever calibration changes.

src/drivers/telemetry/hott/messages.cpp

@@ -150,7 +150,7 @@ build_eam_response(uint8_t *buffer, size_t *size)
 	msg.eam_sensor_id = EAM_SENSOR_ID;
 	msg.sensor_text_id = EAM_SENSOR_TEXT_ID;
 
-	msg.temperature1 = (uint8_t)(airdata.baro_temp_celcius + 20);
+	msg.temperature1 = (uint8_t)(airdata.ambient_temperature + 20);
 	msg.temperature2 = msg.temperature1 - BOARD_TEMP_OFFSET_DEG;
 
 	msg.main_voltage_L = (uint8_t)(battery.voltage_v * 10);

src/drivers/uavcan/sensors/airspeed.cpp

@@ -104,7 +104,6 @@ UavcanAirspeedBridge::ias_sub_cb(const
 	report.timestamp   		= hrt_absolute_time();
 	report.indicated_airspeed_m_s   = msg.indicated_airspeed;
 	report.true_airspeed_m_s   	= _last_tas_m_s;
-	report.air_temperature_celsius 	= _last_outside_air_temp_k + atmosphere::kAbsoluteNullCelsius;
 
 	publish(msg.getSrcNodeID().get(), &report);
 }

src/modules/airspeed_selector/airspeed_selector_main.cpp

@@ -388,7 +388,7 @@ AirspeedModule::Run()
 				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;
+				input_data.air_temperature_celsius = _vehicle_air_data.ambient_temperature;
 
 				if (_in_takeoff_situation) {
 					// set flag to false if either speed is above stall speed,

src/modules/mavlink/mavlink_receiver.cpp

@@ -2669,7 +2669,6 @@ MavlinkReceiver::handle_message_hil_state_quaternion(mavlink_message_t *msg)
 		airspeed.timestamp_sample = timestamp_sample;
 		airspeed.indicated_airspeed_m_s = hil_state.ind_airspeed * 1e-2f;
 		airspeed.true_airspeed_m_s = hil_state.true_airspeed * 1e-2f;
-		airspeed.air_temperature_celsius = 15.f;
 		airspeed.timestamp = hrt_absolute_time();
 		_airspeed_pub.publish(airspeed);
 	}

src/modules/mavlink/streams/HIGHRES_IMU.hpp

@@ -193,7 +193,7 @@ private:
 			msg.abs_pressure = air_data.baro_pressure_pa;
 			msg.diff_pressure = differential_pressure.differential_pressure_pa;
 			msg.pressure_alt = air_data.baro_alt_meter;
-			msg.temperature = air_data.baro_temp_celcius;
+			msg.temperature = air_data.ambient_temperature;
 			msg.fields_updated = fields_updated;
 
 			mavlink_msg_highres_imu_send_struct(_mavlink->get_channel(), &msg);

src/modules/mavlink/streams/HIGH_LATENCY2.hpp

@@ -57,6 +57,7 @@
 #include <uORB/topics/vehicle_status.h>
 #include <uORB/topics/failsafe_flags.h>
 #include <uORB/topics/health_report.h>
+#include <uORB/topics/vehicle_air_data.h>
 
 #include <px4_platform_common/events.h>
 
@@ -521,6 +522,7 @@ private:
 		update_gps();
 		update_vehicle_status();
 		update_wind();
+		update_vehicle_air_data();
 	}
 
 	void update_airspeed()
@@ -529,7 +531,6 @@ private:
 
 		if (_airspeed_sub.update(&airspeed)) {
 			_airspeed.add_value(airspeed.indicated_airspeed_m_s, _update_rate_filtered);
-			_temperature.add_value(airspeed.air_temperature_celsius, _update_rate_filtered);
 		}
 	}
 
@@ -610,6 +611,15 @@ private:
 		}
 	}
 
+	void update_vehicle_air_data()
+	{
+		vehicle_air_data_s air_data;
+
+		if (_vehicle_air_data_sub.update(&air_data)) {
+			_temperature.add_value(air_data.ambient_temperature, _update_rate_filtered);
+		}
+	}
+
 	void set_default_values(mavlink_high_latency2_t &msg) const
 	{
 		msg.airspeed = 0;
@@ -659,6 +669,7 @@ private:
 	uORB::Subscription _tecs_status_sub{ORB_ID(tecs_status)};
 	uORB::Subscription _wind_sub{ORB_ID(wind)};
 	uORB::Subscription _health_report_sub{ORB_ID(health_report)};
+	uORB::Subscription _vehicle_air_data_sub{ORB_ID(vehicle_air_data)};
 
 	SimpleAnalyzer _airspeed;
 	SimpleAnalyzer _airspeed_sp;

src/modules/sensors/sensors.cpp

@@ -278,32 +278,15 @@ void Sensors::diff_pres_poll()
 
 		vehicle_air_data_s air_data{};
 		_vehicle_air_data_sub.copy(&air_data);
-
-		float air_temperature_celsius = NAN;
-
-		// assume anything outside of a (generous) operating range of -40C to 125C is invalid
-		if (PX4_ISFINITE(diff_pres.temperature) && (diff_pres.temperature >= -40.f) && (diff_pres.temperature <= 125.f)) {
-
-			air_temperature_celsius = diff_pres.temperature;
-
-		} else {
-			// differential pressure temperature invalid, check barometer
-			if ((air_data.timestamp != 0) && PX4_ISFINITE(air_data.baro_temp_celcius)
-			    && (air_data.baro_temp_celcius >= -40.f) && (air_data.baro_temp_celcius <= 125.f)) {
-
-				// TODO: review PCB_TEMP_ESTIMATE_DEG, ignore for external baro
-				air_temperature_celsius = air_data.baro_temp_celcius - PCB_TEMP_ESTIMATE_DEG;
-			}
-		}
+		const float temperature = air_data.ambient_temperature;
 
 		// push raw data into validator
-		float airspeed_input[3] { diff_pres.differential_pressure_pa, air_temperature_celsius, 0.0f };
+		float airspeed_input[3] { diff_pres.differential_pressure_pa, 0.0f, 0.0f };
 		_airspeed_validator.put(diff_pres.timestamp_sample, airspeed_input, diff_pres.error_count, 100); // TODO: real priority?
 
 		// accumulate average for publication
 		_diff_pres_timestamp_sum += diff_pres.timestamp_sample;
 		_diff_pres_pressure_sum += diff_pres.differential_pressure_pa;
-		_diff_pres_temperature_sum += air_temperature_celsius;
 		_baro_pressure_sum += air_data.baro_pressure_pa;
 		_diff_pres_count++;
 
@@ -313,12 +296,10 @@ void Sensors::diff_pres_poll()
 			const uint64_t timestamp_sample = _diff_pres_timestamp_sum / _diff_pres_count;
 			const float differential_pressure_pa = _diff_pres_pressure_sum / _diff_pres_count - _parameters.diff_pres_offset_pa;
 			const float baro_pressure_pa = _baro_pressure_sum / _diff_pres_count;
-			const float temperature = _diff_pres_temperature_sum / _diff_pres_count;
 
 			// reset
 			_diff_pres_timestamp_sum = 0;
 			_diff_pres_pressure_sum = 0;
-			_diff_pres_temperature_sum = 0;
 			_baro_pressure_sum = 0;
 			_diff_pres_count = 0;
 
@@ -354,7 +335,6 @@ void Sensors::diff_pres_poll()
 				airspeed.timestamp_sample = timestamp_sample;
 				airspeed.indicated_airspeed_m_s = indicated_airspeed_m_s;
 				airspeed.true_airspeed_m_s = true_airspeed_m_s;
-				airspeed.air_temperature_celsius = temperature;
 				airspeed.confidence = _airspeed_validator.confidence(hrt_absolute_time());
 				airspeed.timestamp = hrt_absolute_time();
 				_airspeed_pub.publish(airspeed);

src/modules/sensors/sensors.hpp

@@ -90,11 +90,7 @@
 
 using namespace sensors;
 using namespace time_literals;
-/**
- * HACK - true temperature is much less than indicated temperature in baro,
- * subtract 5 degrees in an attempt to account for the electrical upheating of the PCB
- */
-#define PCB_TEMP_ESTIMATE_DEG		5.0f
+
 class Sensors : public ModuleBase<Sensors>, public ModuleParams, public px4::ScheduledWorkItem
 {
 public:

src/modules/sensors/vehicle_air_data/VehicleAirData.cpp

@@ -45,6 +45,9 @@ using namespace matrix;
 using namespace atmosphere;
 
 static constexpr uint32_t SENSOR_TIMEOUT{300_ms};
+static constexpr float DEFAULT_TEMPERATURE_CELSIUS = 15.f;
+static constexpr float TEMPERATURE_MIN_CELSIUS = -60.f;
+static constexpr float TEMPERATURE_MAX_CELSIUS = 60.f;
 
 VehicleAirData::VehicleAirData() :
 	ModuleParams(nullptr),
@@ -77,21 +80,23 @@ void VehicleAirData::Stop()
 	}
 }
 
-void VehicleAirData::AirTemperatureUpdate()
+float VehicleAirData::AirTemperatureUpdate(const float temperature_baro, TemperatureSource &source,
+		const hrt_abstime time_now_us)
 {
+	// use the temperature from the differential pressure sensor if available
+	// otherwise use the temperature from the external barometer
+	// Temperature measurements from internal baros are not used as typically not representative for ambient temperature
+	float temperature = source == TemperatureSource::EXTERNAL_BARO ? temperature_baro : DEFAULT_TEMPERATURE_CELSIUS;
 	differential_pressure_s differential_pressure;
 
-	static constexpr float temperature_min_celsius = -20.f;
-	static constexpr float temperature_max_celsius = 35.f;
-
-	// update air temperature if data from differential pressure sensor is finite and not exactly 0
-	// limit the range to max 35°C to limt the error due to heated up airspeed sensors prior flight
-	if (_differential_pressure_sub.update(&differential_pressure) && PX4_ISFINITE(differential_pressure.temperature)
-	    && fabsf(differential_pressure.temperature) > FLT_EPSILON) {
-
-		_air_temperature_celsius = math::constrain(differential_pressure.temperature, temperature_min_celsius,
-					   temperature_max_celsius);
+	if (_differential_pressure_sub.copy(&differential_pressure)
+	    && time_now_us - differential_pressure.timestamp_sample < 1_s
+	    && PX4_ISFINITE(differential_pressure.temperature)) {
+		temperature = differential_pressure.temperature;
+		source = TemperatureSource::AIRSPEED;
 	}
+
+	return math::constrain(temperature, TEMPERATURE_MIN_CELSIUS, TEMPERATURE_MAX_CELSIUS);
 }
 
 bool VehicleAirData::ParametersUpdate(bool force)
@@ -139,8 +144,6 @@ void VehicleAirData::Run()
 
 	const bool parameter_update = ParametersUpdate();
 
-	AirTemperatureUpdate();
-
 	estimator_status_flags_s estimator_status_flags;
 	const bool estimator_status_flags_updated = _estimator_status_flags_sub.update(&estimator_status_flags);
 
@@ -272,23 +275,26 @@ void VehicleAirData::Run()
 
 					if (publish) {
 						const float pressure_pa = _data_sum[instance] / _data_sum_count[instance];
-						const float temperature = _temperature_sum[instance] / _data_sum_count[instance];
+						const float temperature_baro = _temperature_sum[instance] / _data_sum_count[instance];
+						TemperatureSource temperature_source = _calibration[instance].external() ? TemperatureSource::EXTERNAL_BARO :
+										       TemperatureSource::DEFAULT_TEMP;
+						const float ambient_temperature = AirTemperatureUpdate(temperature_baro, temperature_source, time_now_us);
 
 						const float pressure_sealevel_pa = _param_sens_baro_qnh.get() * 100.f;
 						const float altitude = getAltitudeFromPressure(pressure_pa, pressure_sealevel_pa);
 
 						// calculate air density
-						const float air_density = getDensityFromPressureAndTemp(pressure_pa, temperature);
+						const float air_density = getDensityFromPressureAndTemp(pressure_pa, ambient_temperature);
 
 						// populate vehicle_air_data with and publish
 						vehicle_air_data_s out{};
 						out.timestamp_sample = timestamp_sample;
 						out.baro_device_id = _calibration[instance].device_id();
 						out.baro_alt_meter = altitude;
-						out.baro_temp_celcius = temperature;
+						out.ambient_temperature = ambient_temperature;
+						out.temperature_source = static_cast<uint8_t>(temperature_source);
 						out.baro_pressure_pa = pressure_pa;
 						out.rho = air_density;
-						out.eas2tas = sqrtf(kAirDensitySeaLevelStandardAtmos / math::max(air_density, FLT_EPSILON));
 						out.calibration_count = _calibration[instance].calibration_count();
 						out.timestamp = hrt_absolute_time();
 

src/modules/sensors/vehicle_air_data/VehicleAirData.hpp

@@ -73,9 +73,15 @@ public:
 	void PrintStatus();
 
 private:
+	enum TemperatureSource {
+		DEFAULT_TEMP = 0,
+		EXTERNAL_BARO = 1,
+		AIRSPEED = 2,
+	};
+
 	void Run() override;
 
-	void AirTemperatureUpdate();
+	float AirTemperatureUpdate(const float temperature_baro, TemperatureSource &source, const hrt_abstime time_now_us);
 	void CheckFailover(const hrt_abstime &time_now_us);
 	bool ParametersUpdate(bool force = false);
 	void UpdateStatus();
@@ -124,8 +130,6 @@ private:
 
 	int8_t _selected_sensor_sub_index{-1};
 
-	float _air_temperature_celsius{20.f}; // initialize with typical 20degC ambient temperature
-
 	bool _last_status_baro_fault{false};
 
 	DEFINE_PARAMETERS(

src/modules/simulation/simulator_sih/sih.cpp

@@ -556,7 +556,6 @@ void Sih::send_airspeed(const hrt_abstime &time_now_us)
 	// regardless of vehicle type, body frame, etc this holds as long as wind=0
 	airspeed.true_airspeed_m_s = fmaxf(0.1f, _v_E.norm() + generate_wgn() * 0.2f);
 	airspeed.indicated_airspeed_m_s = airspeed.true_airspeed_m_s * sqrtf(_wing_l.get_rho() / RHO);
-	airspeed.air_temperature_celsius = NAN;
 	airspeed.confidence = 0.7f;
 	airspeed.timestamp = hrt_absolute_time();
 	_airspeed_pub.publish(airspeed);