EKF: Add a fixed wing mode with setter function

EKF/common.h

@@ -412,6 +412,7 @@ union filter_control_status_u {
 		uint32_t ev_hgt      : 1; // 14 - true when height data from external vision measurements is being fused
 		uint32_t fuse_beta   : 1; // 15 - true when synthetic sideslip measurements are being fused
 		uint32_t update_mag_states_only   : 1; // 16 - true when only the magnetometer states are updated by the magnetometer
+		uint32_t fixed_wing  : 1; // 17 - true when the vehicle is operating as a fixed wing vehicle
 	} flags;
 	uint32_t value;
 };

EKF/control.cpp

@@ -1050,14 +1050,12 @@ void Ekf::controlMagFusion()
 				if (!_control_status.flags.mag_3D) {
 					if (!_flt_mag_align_complete) {
 						// If we are flying a vehicle that flies forward, eg plane, then we can use the GPS course to check and correct the heading
-						// if we are doing wind estimation and using the zero sideslip assumotion, then it is reasonable to assume the plane is flying forward
-						bool zeroSideslipValid = _control_status.flags.fuse_beta;
-						if (zeroSideslipValid) {
-							_flt_mag_align_complete = _control_status.flags.yaw_align = realignYawGPS();
-
+						if (_control_status.flags.fixed_wing) {
+							_control_status.flags.yaw_align = realignYawGPS();
+							_flt_mag_align_complete = _control_status.flags.yaw_align;
 						} else {
-							_flt_mag_align_complete = _control_status.flags.yaw_align = resetMagHeading(_mag_sample_delayed.mag);
-
+							_control_status.flags.yaw_align = resetMagHeading(_mag_sample_delayed.mag);
+							_flt_mag_align_complete = _control_status.flags.yaw_align;
 						}
 					} else {
 						// reset the mag field covariances

EKF/estimator_interface.h

@@ -181,6 +181,9 @@ public:
 	// set vehicle landed status data
 	void set_in_air_status(bool in_air) {_control_status.flags.in_air = in_air;}
 
+	// set vehicle is fixed wing status
+	void set_is_fixed_wing(bool is_fixed_wing) {_control_status.flags.fixed_wing = is_fixed_wing;}
+
 	// set flag if synthetic sideslip measurement should be fused
 	void set_fuse_beta_flag(bool fuse_beta) {_control_status.flags.fuse_beta = fuse_beta;}