AirspeedValidator: Remvoe airspeed variance after boot check (#20678)

This checks was introduced to catch the (unlikely) case of the driver publishing
a stale value that is not actually from a current measurement right after boot.
This was done by declaring it invalid if there is no update of the measurement
within the first 10s after boot.
Practice though has shown that around 0, many airspeed sensors have such a low
resolution that the reported airspeed value is often at the exact same value
for longer periods of time on totally healthy sensors, and thus we trigger
some false positive failure detections.
Given that this failure mode (driver publishing stale data) is quite rare (if
it doesn't receive new data it should stop publishing), I remove this check
here again.
When in aerodynamic flight mode and armed, there is still the data stuck
check that can trigger if there is no update for 2s.

Signed-off-by: Silvan Fuhrer <silvan@auterion.com>

src/modules/airspeed_selector/AirspeedValidator.cpp

@@ -57,7 +57,6 @@ AirspeedValidator::update_airspeed_validator(const airspeed_validator_update_dat
 			      input_data.ground_velocity, input_data.lpos_evh, input_data.lpos_evv, input_data.att_q);
 	update_in_fixed_wing_flight(input_data.in_fixed_wing_flight);
 	check_airspeed_data_stuck(input_data.timestamp);
-	check_airspeed_data_variation(input_data.timestamp);
 	check_load_factor(input_data.accel_z);
 	check_airspeed_innovation(input_data.timestamp, input_data.vel_test_ratio, input_data.mag_test_ratio,
 				  input_data.ground_velocity);
@@ -213,36 +212,6 @@ AirspeedValidator::check_airspeed_data_stuck(uint64_t time_now)
 	_data_stuck_test_failed = hrt_elapsed_time(&_time_last_unequal_data) > DATA_STUCK_TIMEOUT && _in_fixed_wing_flight;
 }
 
-void
-AirspeedValidator::check_airspeed_data_variation(uint64_t time_now)
-{
-	// Data variation after boot test: trigger when IAS is not changing for within VARIATION_CHECK_TIMEOUT
-	// after the first data is received.
-
-	if (!_data_variation_check_enabled) {
-		_data_variation_test_failed = false;
-		return;
-	}
-
-	if (_time_first_data == 0) {
-		// init
-		_time_first_data = time_now;
-		_data_variation_check_ias_prev = _IAS;
-	}
-
-	if (!_variation_detected && (time_now - _time_first_data < VARIATION_CHECK_TIMEOUT)) {
-		if (fabsf(_IAS - _data_variation_check_ias_prev) > FLT_EPSILON) {
-			_variation_detected = true;
-		}
-
-		_data_variation_check_ias_prev = _IAS;
-
-	} else {
-		// only update the test_failed flag once the timeout since first data is over
-		_data_variation_test_failed = !_variation_detected;
-	}
-}
-
 void
 AirspeedValidator::check_airspeed_innovation(uint64_t time_now, float estimator_status_vel_test_ratio,
 		float estimator_status_mag_test_ratio, const matrix::Vector3f &vI)
@@ -321,13 +290,13 @@ AirspeedValidator::check_load_factor(float accel_z)
 void
 AirspeedValidator::update_airspeed_valid_status(const uint64_t timestamp)
 {
-	if (_data_variation_test_failed || _data_stuck_test_failed || _innovations_check_failed || _load_factor_check_failed) {
-		// at least one check (variation, data stuck, innovation or load factor) failed, so record timestamp
+	if (_data_stuck_test_failed || _innovations_check_failed || _load_factor_check_failed) {
+		// at least one check (data stuck, innovation or load factor) failed, so record timestamp
 		_time_checks_failed = timestamp;
 
-	} else if (!_data_variation_test_failed && ! _data_stuck_test_failed && !_innovations_check_failed
+	} else if (! _data_stuck_test_failed && !_innovations_check_failed
 		   && !_load_factor_check_failed) {
-		// all checks(variation, data stuck, innovation and load factor) must pass to declare airspeed good
+		// all checks(data stuck, innovation and load factor) must pass to declare airspeed good
 		_time_checks_passed = timestamp;
 	}
 
@@ -340,7 +309,7 @@ AirspeedValidator::update_airspeed_valid_status(const uint64_t timestamp)
 		// a timeout period is applied.
 		const bool single_check_fail_timeout = (timestamp - _time_checks_passed) > _checks_fail_delay * 1_s;
 
-		if (both_checks_failed || single_check_fail_timeout || _data_variation_test_failed || _data_stuck_test_failed) {
+		if (both_checks_failed || single_check_fail_timeout || _data_stuck_test_failed) {
 
 			_airspeed_valid = false;
 		}

src/modules/airspeed_selector/AirspeedValidator.hpp

@@ -118,7 +118,6 @@ public:
 	void set_enable_data_stuck_check(bool enable) { _data_stuck_check_enabled = enable; }
 	void set_enable_innovation_check(bool enable) { _innovation_check_enabled = enable; }
 	void set_enable_load_factor_check(bool enable) { _load_factor_check_enabled = enable; }
-	void set_enable_data_variation_check(bool enable) { _data_variation_check_enabled = enable; }
 
 private:
 
@@ -147,13 +146,6 @@ private:
 	float _IAS_prev{0.f};
 	static constexpr uint64_t DATA_STUCK_TIMEOUT{2_s}; ///< timeout after which data stuck check triggers when data is flat
 
-	// variation check
-	bool _data_variation_test_failed{false};
-	static constexpr uint64_t VARIATION_CHECK_TIMEOUT{10_s}; ///< timeout to check for data variation after first data is received
-	hrt_abstime _time_first_data{0};
-	float _data_variation_check_ias_prev{0.f};
-	bool _variation_detected{false};
-
 	// states of innovation check
 	bool _innovations_check_failed{false};  ///< true when airspeed innovations have failed consistency checks
 	float _tas_innov_threshold{1.0}; ///< innovation error threshold for triggering innovation check failure
@@ -193,7 +185,6 @@ private:
 	void update_CAS_scale_applied();
 	void update_CAS_TAS(float air_pressure_pa, float air_temperature_celsius);
 	void check_airspeed_data_stuck(uint64_t timestamp);
-	void check_airspeed_data_variation(uint64_t timestamp);
 	void check_airspeed_innovation(uint64_t timestamp, float estimator_status_vel_test_ratio,
 				       float estimator_status_mag_test_ratio, const matrix::Vector3f &vI);
 	void check_load_factor(float accel_z);

src/modules/airspeed_selector/airspeed_selector_main.cpp

@@ -162,8 +162,7 @@ private:
 		CHECK_TYPE_ONLY_DATA_MISSING_BIT = (1 << 0),
 		CHECK_TYPE_DATA_STUCK_BIT = (1 << 1),
 		CHECK_TYPE_INNOVATION_BIT = (1 << 2),
-		CHECK_TYPE_LOAD_FACTOR_BIT = (1 << 3),
-		CHECK_TYPE_DATA_VARIATION_BIT = (1 << 4)
+		CHECK_TYPE_LOAD_FACTOR_BIT = (1 << 3)
 	};
 
 	DEFINE_PARAMETERS(
@@ -480,8 +479,6 @@ void AirspeedModule::update_params()
 				CheckTypeBits::CHECK_TYPE_INNOVATION_BIT);
 		_airspeed_validator[i].set_enable_load_factor_check(_param_airspeed_checks_on.get() &
 				CheckTypeBits::CHECK_TYPE_LOAD_FACTOR_BIT);
-		_airspeed_validator[i].set_enable_data_variation_check(_param_airspeed_checks_on.get() &
-				CheckTypeBits::CHECK_TYPE_DATA_VARIATION_BIT);
 	}
 }
 

src/modules/airspeed_selector/airspeed_selector_params.c

@@ -151,15 +151,14 @@ PARAM_DEFINE_INT32(ASPD_PRIMARY, 1);
  * Note that the data missing check is enabled if any of the options is set.
  *
  * @min 0
- * @max 31
+ * @max 15
  * @bit 0 Only data missing check (triggers if more than 1s no data)
  * @bit 1 Data stuck (triggers if data is exactly constant for 2s in FW mode)
  * @bit 2 Innovation check (see ASPD_FS_INNOV)
  * @bit 3 Load factor check (triggers if measurement is below stall speed)
- * @bit 4 Check for data variation in first 10s after sensor connection
  * @group Airspeed Validator
  */
-PARAM_DEFINE_INT32(ASPD_DO_CHECKS, 23);
+PARAM_DEFINE_INT32(ASPD_DO_CHECKS, 7);
 
 /**
  * Enable fallback to sensor-less airspeed estimation