AP_LandingGear: Helper for landing

libraries/AP_LandingGear/AP_LandingGear.cpp

@@ -198,7 +198,11 @@ void AP_LandingGear::update(float height_above_ground_m)
     
     if (_pin_deployed == -1) {
         last_gear_event_ms = 0;
-        gear_state_current = (_deployed == true ? LG_DEPLOYED : LG_RETRACTED);
+        
+        // If there was no pilot input and state is still unknown - leave it as it is
+        if (gear_state_current != LG_UNKNOWN) {
+            gear_state_current = (_deployed == true ? LG_DEPLOYED : LG_RETRACTED);
+        }
     } else {
         LG_LandingGear_State gear_state_new;
         
@@ -250,3 +254,14 @@ void AP_LandingGear::log_wow_state(LG_WOW_State state)
                                            AP_HAL::micros64(),
                                            (int8_t)gear_state_current, (int8_t)state);
 }
+
+bool AP_LandingGear::check_before_land(void)
+{
+    // If the landing gear state is not known (most probably as it is not used)
+    if (get_state() == LG_UNKNOWN) {
+        return true;
+    }
+    
+    // If the landing gear was not used - return true, otherwise - check for deployed
+    return (get_state() == LG_DEPLOYED);
+}

libraries/AP_LandingGear/AP_LandingGear.h

@@ -83,6 +83,8 @@ public:
     
     void update(float height_above_ground_m);
     
+    bool check_before_land(void);
+
 private:
     // Parameters
     AP_Int8     _startup_behaviour;     // start-up behaviour (see LandingGearStartupBehaviour)