AP_InertialNav: Remove unused get_pos_z_derivative

libraries/AP_InertialNav/AP_InertialNav_NavEKF.cpp

@@ -36,13 +36,6 @@ void AP_InertialNav_NavEKF::update(float dt)
         _velocity_cm = velNED * 100; // convert to cm/s
         _velocity_cm.z = -_velocity_cm.z; // convert from NED to NEU
     }
-
-    // Get a derivative of the vertical position which is kinematically consistent with the vertical position is required by some control loops.
-    // This is different to the vertical velocity from the EKF which is not always consistent with the vertical position due to the various errors that are being corrected for.
-    if (_ahrs_ekf.get_vert_pos_rate(_pos_z_rate)) {
-        _pos_z_rate *= 100; // convert to cm/s
-        _pos_z_rate = - _pos_z_rate; // InertialNav is NEU
-    }
 }
 
 /**
@@ -127,14 +120,6 @@ float AP_InertialNav_NavEKF::get_speed_xy() const
     return norm(_velocity_cm.x, _velocity_cm.y);
 }
 
-/**
- * get_pos_z_derivative - returns the derivative of the z position in cm/s
-*/
-float AP_InertialNav_NavEKF::get_pos_z_derivative() const
-{
-    return _pos_z_rate;
-}
-
 /**
  * get_altitude - get latest altitude estimate in cm
  * @return

libraries/AP_InertialNav/AP_InertialNav_NavEKF.h

@@ -70,11 +70,6 @@ public:
      */
     const Vector3f&    get_velocity() const override;
 
-    /**
-     * get_pos_z_derivative - returns the derivative of the z position in cm/s
-    */
-    float    get_pos_z_derivative() const;
-
     /**
      * get_speed_xy - returns the current horizontal speed in cm/s
      *
@@ -100,7 +95,6 @@ public:
 private:
     Vector3f _relpos_cm;   // NEU
     Vector3f _velocity_cm; // NEU
-    float _pos_z_rate;
     struct Location _abspos;
     bool _haveabspos;
     AP_AHRS_NavEKF &_ahrs_ekf;