EKF: Add true airspeed accessor

EKF/airspeed_fusion.cpp

@@ -225,6 +225,12 @@ void Ekf::get_wind_velocity(float *wind)
 	wind[1] = _state.wind_vel(1);
 }
 
+void Ekf::get_true_airspeed(float *tas)
+{
+	float tempvar = sqrtf(sq(_state.vel(0) - _state.wind_vel(0)) + sq(_state.vel(1) - _state.wind_vel(1)) + sq(_state.vel(2)));
+	memcpy(tas, &tempvar, sizeof(float));
+}
+
 /*
  * Reset the wind states using the current airspeed measurement, ground relative nav velocity, yaw angle and assumption of zero sideslip
 */

EKF/ekf.h

@@ -112,6 +112,9 @@ public:
 	// get the wind velocity in m/s
 	void get_wind_velocity(float *wind);
 
+	// get the true airspeed in m/s
+	void get_true_airspeed(float *tas);
+
 	// get the diagonal elements of the covariance matrix
 	void get_covariances(float *covariances);
 

EKF/estimator_interface.h

@@ -93,6 +93,8 @@ public:
 
 	virtual void get_wind_velocity(float *wind) = 0;
 
+	virtual void get_true_airspeed(float *tas) = 0;
+
 	virtual void get_covariances(float *covariances) = 0;
 
 	// gets the variances for the NED velocity states