AP_SmartRTL: Add option to ignore pilot yaw

libraries/AP_SmartRTL/AP_SmartRTL.cpp

@@ -36,6 +36,13 @@ const AP_Param::GroupInfo AP_SmartRTL::var_info[] = {
     // @RebootRequired: True
     AP_GROUPINFO("POINTS", 1, AP_SmartRTL, _points_max, SMARTRTL_POINTS_DEFAULT),
 
+    // @Param: OPTIONS
+    // @DisplayName: SmartRTL options
+    // @Description: Bitmask of SmartRTL options.
+    // @Bitmask: 2:Ignore pilot yaw
+    // @User: Standard
+    AP_GROUPINFO("OPTIONS", 2, AP_SmartRTL, _options, 0),
+
     AP_GROUPEND
 };
 
@@ -861,3 +868,10 @@ bool AP_SmartRTL::loops_overlap(const prune_loop_t &loop1, const prune_loop_t &l
     // if we got here, no overlap
     return false;
 }
+
+// returns true if pilot's yaw input should be used to adjust vehicle's heading
+bool AP_SmartRTL::use_pilot_yaw(void) const
+{
+    return (_options.get() & uint32_t(Options::IgnorePilotYaw)) == 0;
+}
+

libraries/AP_SmartRTL/AP_SmartRTL.h

@@ -74,6 +74,9 @@ public:
     // run background cleanup - should be run regularly from the IO thread
     void run_background_cleanup();
 
+    // returns true if pilot's yaw input should be used to adjust vehicle's heading
+    bool use_pilot_yaw(void) const;
+
     // parameter var table
     static const struct AP_Param::GroupInfo var_info[];
 
@@ -94,6 +97,12 @@ private:
         SRTL_DEACTIVATED_PROGRAM_ERROR,
     };
 
+    // enum for SRTL_OPTIONS parameter
+    enum class Options : int32_t {
+        // bits 1 and 2 are still available, pilot yaw was mapped to bit 2 for symmetry with auto
+        IgnorePilotYaw    = (1U << 2),
+    };
+
     // add point to end of path
     bool add_point(const Vector3f& point);
 
@@ -164,6 +173,7 @@ private:
     // parameters
     AP_Float _accuracy;
     AP_Int16 _points_max;
+    AP_Int32 _options;
 
     // SmartRTL State Variables
     bool _active;       // true if SmartRTL is usable.  may become unusable if the path becomes too long to keep in memory, and too convoluted to be cleaned up, SmartRTL will be permanently deactivated (for the remainder of the flight)