ekf2: refactor wind reset functions

src/modules/ekf2/EKF/airspeed_fusion.cpp

@@ -96,8 +96,7 @@ void Ekf::fuseAirspeed()
 		const char *action_string = nullptr;
 
 		if (update_wind_only) {
-			resetWindStates();
+			resetWindUsingAirspeed();
-			resetWindCovariance();
 			action_string = "wind";
 
 		} else {
@@ -173,22 +172,38 @@ float Ekf::getTrueAirspeed() const
 	return (_state.vel - Vector3f(_state.wind_vel(0), _state.wind_vel(1), 0.f)).norm();
 }
 
+void Ekf::resetWind()
+{
+	if (_control_status.flags.fuse_aspd) {
+		resetWindUsingAirspeed();
+
+	} else {
+		resetWindToZero();
+	}
+}
+
 /*
  * Reset the wind states using the current airspeed measurement, ground relative nav velocity, yaw angle and assumption of zero sideslip
 */
-void Ekf::resetWindStates()
+void Ekf::resetWindUsingAirspeed()
 {
 	const float euler_yaw = shouldUse321RotationSequence(_R_to_earth)
 				? getEuler321Yaw(_state.quat_nominal)
 				: getEuler312Yaw(_state.quat_nominal);
 
-	if (_tas_data_ready && (_imu_sample_delayed.time_us - _airspeed_sample_delayed.time_us < (uint64_t)5e5)) {
 	// estimate wind using zero sideslip assumption and airspeed measurement if airspeed available
 	_state.wind_vel(0) = _state.vel(0) - _airspeed_sample_delayed.true_airspeed * cosf(euler_yaw);
 	_state.wind_vel(1) = _state.vel(1) - _airspeed_sample_delayed.true_airspeed * sinf(euler_yaw);
 
-	} else {
+	resetWindCovarianceUsingAirspeed();
+
+	_time_last_arsp_fuse = _time_last_imu;
+}
+
+void Ekf::resetWindToZero()
+{
 	// If we don't have an airspeed measurement, then assume the wind is zero
 	_state.wind_vel.setZero();
-	}
+	// start with a small initial uncertainty to improve the initial estimate
+	P.uncorrelateCovarianceSetVariance<2>(22, _params.initial_wind_uncertainty);
 }

src/modules/ekf2/EKF/control.cpp

@@ -1333,17 +1333,7 @@ void Ekf::controlAirDataFusion()
 			}
 
 		} else if (starting_conditions_passing) {
-			// If starting wind state estimation, reset the wind states and covariances before fusing any data
-			if (!_control_status.flags.wind) {
-				// activate the wind states
-				_control_status.flags.wind = true;
-				// reset the wind speed states and corresponding covariances
-				resetWindStates();
-				resetWindCovariance();
-			}
-
 			startAirspeedFusion();
-			_time_last_arsp_fuse = _time_last_imu;
 		}
 
 	} else if (_control_status.flags.fuse_aspd && (_imu_sample_delayed.time_us - _airspeed_sample_delayed.time_us > (uint64_t) 1e6)) {
@@ -1370,9 +1360,7 @@ void Ekf::controlBetaFusion()
 			_control_status.flags.wind = true;
 			// reset the timeout timers to prevent repeated resets
 			_time_last_beta_fuse = _time_last_imu;
-			// reset the wind speed states and corresponding covariances
+			resetWind();
-			resetWindStates();
-			resetWindCovariance();
 		}
 
 		fuseSideslip();
@@ -1389,8 +1377,7 @@ void Ekf::controlDragFusion()
 		if (!_control_status.flags.wind) {
 			// reset the wind states and covariances when starting drag accel fusion
 			_control_status.flags.wind = true;
-			resetWindStates();
+			resetWind();
-			resetWindCovariance();
 
 		} else if (_drag_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_drag_sample_delayed)) {
 			fuseDrag();

src/modules/ekf2/EKF/covariance.cpp

@@ -1140,9 +1140,8 @@ void Ekf::resetZDeltaAngBiasCov()
 	P.uncorrelateCovarianceSetVariance<1>(12, init_delta_ang_bias_var);
 }
 
-void Ekf::resetWindCovariance()
+void Ekf::resetWindCovarianceUsingAirspeed()
 {
-	if (_tas_data_ready && (_imu_sample_delayed.time_us - _airspeed_sample_delayed.time_us < (uint64_t)5e5)) {
 	// Derived using EKF/matlab/scripts/Inertial Nav EKF/wind_cov.py
 	// TODO: explicitly include the sideslip angle in the derivation
 	const float euler_yaw = getEuler321Yaw(_state.quat_nominal);
@@ -1170,9 +1169,4 @@ void Ekf::resetWindCovariance()
 	// Now add the variance due to uncertainty in vehicle velocity that was used to calculate the initial wind speed
 	P(22, 22) += P(4, 4);
 	P(23, 23) += P(5, 5);
-
-	} else {
-		// without airspeed, start with a small initial uncertainty to improve the initial estimate
-		P.uncorrelateCovarianceSetVariance<2>(22, _params.initial_wind_uncertainty);
-	}
 }

src/modules/ekf2/EKF/ekf.h

@@ -917,10 +917,12 @@ private:
 	void resetMagCov();
 
 	// perform a limited reset of the wind state covariances
-	void resetWindCovariance();
+	void resetWindCovarianceUsingAirspeed();
 
-	// perform a reset of the wind states
+	// perform a reset of the wind states and related covariances
-	void resetWindStates();
+	void resetWind();
+	void resetWindUsingAirspeed();
+	void resetWindToZero();
 
 	// check that the range finder data is continuous
 	void updateRangeDataContinuity();

src/modules/ekf2/EKF/ekf_helper.cpp

@@ -1480,11 +1480,21 @@ void Ekf::loadMagCovData()
 	P.slice<2, 2>(16, 16) = _saved_mag_ef_covmat;
 }
 
-void Ekf::startAirspeedFusion() {
+void Ekf::startAirspeedFusion()
+{
+	// If starting wind state estimation, reset the wind states and covariances before fusing any data
+	if (!_control_status.flags.wind) {
+		// activate the wind states
+		_control_status.flags.wind = true;
+		// reset the wind speed states and corresponding covariances
+		resetWindUsingAirspeed();
+	}
+
 	_control_status.flags.fuse_aspd = true;
 }
 
-void Ekf::stopAirspeedFusion() {
+void Ekf::stopAirspeedFusion()
+{
 	_control_status.flags.fuse_aspd = false;
 }
 

src/modules/ekf2/EKF/sideslip_fusion.cpp

@@ -140,8 +140,7 @@ void Ekf::fuseSideslip()
 			const char *action_string = nullptr;
 
 			if (update_wind_only) {
-				resetWindStates();
+				resetWind();
-				resetWindCovariance();
 				action_string = "wind";
 
 			} else {