EKF: Add variables to monitor vertical position and height offset

EKF/ekf.cpp

@@ -85,7 +85,11 @@ Ekf::Ekf():
 	_baro_hgt_faulty(false),
 	_gps_hgt_faulty(false),
 	_rng_hgt_faulty(false),
-	_baro_hgt_offset(0.0f)
+	_baro_hgt_offset(0.0f),
+	_vert_pos_reset_delta(0.0f),
+	_time_vert_pos_reset(0),
+	_vert_vel_reset_delta(0.0f),
+	_time_vert_vel_reset(0)
 {
 	_state = {};
 	_last_known_posNE.setZero();

EKF/ekf.h

@@ -232,6 +232,10 @@ private:
 	int _primary_hgt_source;	// priary source of height data set at initialisation
 
 	float _baro_hgt_offset;		// number of metres the baro height origin is above the local NED origin (m)
+	float _vert_pos_reset_delta;	// increase in vertical position state at the last reset(m)
+	uint64_t _time_vert_pos_reset;	// last system time in usec that the vertical position state was reset
+	float _vert_vel_reset_delta;	// increase in vertical position velocity at the last reset(m)
+	uint64_t _time_vert_vel_reset;	// last system time in usec that the vertical velocity state was reset
 
 	// update the real time complementary filter states. This includes the prediction
 	// and the correction step