AC_AttitudeControl: nfc PosControl fix to say relative to EKF origin

libraries/AC_AttitudeControl/AC_PosControl.h

@@ -243,16 +243,16 @@ public:
 
     /// Position
 
-    /// set_pos_target_xy_cm - sets the position target in NEU cm from home
+    /// set_pos_target_xy_cm - sets the position target, frame NEU in cm relative to the EKF origin
     void set_pos_target_xy_cm(float pos_x, float pos_y) { _pos_target.x = pos_x; _pos_target.y = pos_y; }
 
-    /// get_pos_target_cm - returns the position target in NEU cm from home
+    /// get_pos_target_cm - returns the position target, frame NEU in cm relative to the EKF origin
     const Vector3p& get_pos_target_cm() const { return _pos_target; }
 
-    /// set_pos_target_z_cm - set altitude target in cm above home
+    /// set_pos_target_z_cm - set altitude target in cm above the EKF origin
     void set_pos_target_z_cm(float pos_target) { _pos_target.z = pos_target; }
 
-    /// get_pos_target_z_cm - get target altitude (in cm above home)
+    /// get_pos_target_z_cm - get target altitude (in cm above the EKF origin)
     float get_pos_target_z_cm() const { return _pos_target.z; }
 
     /// get_stopping_point_xy_cm - calculates stopping point in NEU cm based on current position, velocity, vehicle acceleration
@@ -303,13 +303,13 @@ public:
 
     /// Offset
 
-    /// set_pos_offset_target_z_cm - set altitude offset target in cm above home
+    /// set_pos_offset_target_z_cm - set altitude offset target in cm above the EKF origin
     void set_pos_offset_target_z_cm(float pos_offset_target_z) { _pos_offset_target_z = pos_offset_target_z; }
 
-    /// set_pos_offset_z_cm - set altitude offset in cm above home
+    /// set_pos_offset_z_cm - set altitude offset in cm above the EKF origin
     void set_pos_offset_z_cm(float pos_offset_z) { _pos_offset_z = pos_offset_z; }
 
-    /// get_pos_offset_z_cm - returns altitude offset in cm above home
+    /// get_pos_offset_z_cm - returns altitude offset in cm above the EKF origin
     float get_pos_offset_z_cm() const { return _pos_offset_z; }
 
     /// get_vel_offset_z_cm - returns current vertical offset speed in cm/s
@@ -452,15 +452,15 @@ protected:
     float       _yaw_rate_target;       // desired yaw rate in centi-degrees per second calculated by position controller
 
     // position controller internal variables
-    Vector3p    _pos_target;            // target location in NEU cm from home
+    Vector3p    _pos_target;            // target location, frame NEU in cm relative to the EKF origin
     Vector3f    _vel_desired;           // desired velocity in NEU cm/s
     Vector3f    _vel_target;            // velocity target in NEU cm/s calculated by pos_to_rate step
     Vector3f    _accel_desired;         // desired acceleration in NEU cm/s/s (feed forward)
     Vector3f    _accel_target;          // acceleration target in NEU cm/s/s
     Vector3f    _limit_vector;          // the direction that the position controller is limited, zero when not limited
     Vector2f    _vehicle_horiz_vel;     // velocity to use if _flags.vehicle_horiz_vel_override is set
-    float       _pos_offset_target_z;   // vertical position offset target in NEU cm from home
-    float       _pos_offset_z;          // vertical position offset in NEU cm from home
+    float       _pos_offset_target_z;   // vertical position offset target, frame NEU in cm relative to the EKF origin
+    float       _pos_offset_z;          // vertical position offset, frame NEU in cm relative to the EKF origin
     float       _vel_offset_z;          // vertical velocity offset in NEU cm/s calculated by pos_to_rate step
     float       _accel_offset_z;        // vertical acceleration offset in NEU cm/s/s