Added room in land_detector code for free-fall detection

src/modules/land_detector/LandDetector.h

@@ -45,6 +45,15 @@
 #include <uORB/uORB.h>
 #include <uORB/topics/vehicle_land_detected.h>
 
+namespace landdetection
+{
+
+enum LandDetectionResult {
+	LANDDETECTION_RES_FLYING = 0,	/**< UAV is flying */
+	LANDDETECTION_RES_LANDED = 1,	/**< Land has been detected */
+	LANDDETECTION_RES_FREEFALL = 2	/**< Free-fall has been detected */
+};
+
 class LandDetector
 {
 public:
@@ -81,7 +90,7 @@ protected:
 	* @brief Pure abstract method that must be overriden by sub-classes. This actually runs the underlying algorithm
 	* @return true if a landing was detected and this should be broadcast to the rest of the system
 	**/
-	virtual bool update() = 0;
+	virtual LandDetectionResult update() = 0;
 
 	/**
 	* @brief Pure abstract method that is called by this class once for initializing the uderlying algorithm (memory allocation,
@@ -106,6 +115,7 @@ protected:
 	orb_advert_t				_landDetectedPub;		/**< publisher for position in local frame */
 	struct vehicle_land_detected_s		_landDetected;			/**< local vehicle position */
 	uint64_t				_arming_time;			/**< timestamp of arming time */
+	LandDetectionResult _state;		/**< Result of land detection. Can be LANDDETECTION_RES_FLYING, LANDDETECTION_RES_LANDED or LANDDETECTION_RES_FREEFALL */
 
 private:
 	bool _taskShouldExit;                                               /**< true if it is requested that this task should exit */
@@ -115,4 +125,6 @@ private:
 	void		cycle();
 };
 
+}
+
 #endif //__LAND_DETECTOR_H__