AP_Landing: Add an interface to poll if we should be setting fly_forward in AHRS

libraries/AP_Landing/AP_Landing.cpp

@@ -589,3 +589,20 @@ bool AP_Landing::is_throttle_suppressed(void) const
     }
 }
 
+/*
+ * returns false when the vehicle might not be flying forward while landing
+ */
+bool AP_Landing::is_flying_forward(void) const
+{
+    if (!flags.in_progress) {
+        return true;
+    }
+
+    switch (type) {
+    case TYPE_DEEPSTALL:
+        return deepstall.is_flying_forward();
+    case TYPE_STANDARD_GLIDE_SLOPE:
+    default:
+        return true;
+    }
+}

libraries/AP_Landing/AP_Landing.h

@@ -68,6 +68,7 @@ public:
     bool is_on_approach(void) const;
     bool is_ground_steering_allowed(void) const;
     bool is_throttle_suppressed(void) const;
+    bool is_flying_forward(void) const;
     void handle_flight_stage_change(const bool _in_landing_stage);
     int32_t constrain_roll(const int32_t desired_roll_cd, const int32_t level_roll_limit_cd);
     bool get_target_altitude_location(Location &location);

libraries/AP_Landing/AP_Landing_Deepstall.cpp

@@ -343,6 +343,11 @@ bool AP_Landing_Deepstall::is_throttle_suppressed(void) const
     return stage == DEEPSTALL_STAGE_LAND;
 }
 
+bool AP_Landing_Deepstall::is_flying_forward(void) const
+{
+    return stage != DEEPSTALL_STAGE_LAND;
+}
+
 bool AP_Landing_Deepstall::get_target_altitude_location(Location &location)
 {
     memcpy(&location, &landing_point, sizeof(Location));

libraries/AP_Landing/AP_Landing_Deepstall.h

@@ -95,6 +95,7 @@ private:
     bool get_target_altitude_location(Location &location);
     int32_t get_target_airspeed_cm(void) const;
     bool is_throttle_suppressed(void) const;
+    bool is_flying_forward(void) const;
 
     const DataFlash_Class::PID_Info& get_pid_info(void) const;