state_machine_helper: stop mission on RC loss

This allows to still fly missions completely without RC
but reacts if RC is lost during the mission because
the safety pilot expects to be able to take over.

src/modules/commander/state_machine_helper.cpp

@@ -514,22 +514,32 @@ bool set_nav_state(vehicle_status_s *status, actuator_armed_s *armed, commander_
 
 		} else if (status->data_link_lost && data_link_loss_act_configured
 			   && is_armed && !landed) {
-			// Data link lost, data link loss reaction configured, do configured reaction
+			// Data link lost, data link loss reaction configured -> do configured reaction
 			enable_failsafe(status, old_failsafe, mavlink_log_pub, reason_no_datalink);
 			set_link_loss_nav_state(status, armed, status_flags, internal_state, data_link_loss_act, 0);
 
-		} else if (status->rc_signal_lost
+		} else if (status->rc_signal_lost && rc_loss_act_configured && status_flags.rc_signal_found_once
+			   && is_armed && !landed) {
+			// RC link lost, rc loss reaction configured, RC was used before -> RC loss reaction after delay
+			// Safety pilot expects to be able to take over by RC in case anything unexpected happens
+			enable_failsafe(status, old_failsafe, mavlink_log_pub, reason_no_rc);
+			set_link_loss_nav_state(status, armed, status_flags, internal_state, rc_loss_act, param_com_rcl_act_t);
+
+		} else if (status->rc_signal_lost && rc_loss_act_configured
 			   && status->data_link_lost && !data_link_loss_act_configured
 			   && is_armed && !landed) {
-			// All links lost, no data link loss reaction configured, immediately do RC loss reaction
+			// All links lost, no data link loss reaction configured -> immediately do RC loss reaction
+			// Lost all communication, by default it's considered unsafe to continue the mission
+			// Note this case is reached after the previous one when flying mission completely without RC
 			enable_failsafe(status, old_failsafe, mavlink_log_pub, reason_no_datalink);
-			set_link_loss_nav_state(status, armed, status_flags, internal_state, rc_loss_act, param_com_rcl_act_t);
+			set_link_loss_nav_state(status, armed, status_flags, internal_state, rc_loss_act, 0);
 
 		} else if (status->rc_signal_lost && !rc_loss_act_configured
 			   && status->data_link_lost && !data_link_loss_act_configured
 			   && is_armed && !landed
 			   && mission_finished) {
-			// All links lost, all link loss reactions disabled, return after mission to prevent stuck vehicle
+			// All links lost, all link loss reactions disabled -> return after mission
+			// Pilot disabled all reactions, finish mission but then return to avoid lost vehicle
 			enable_failsafe(status, old_failsafe, mavlink_log_pub, reason_no_datalink);
 			set_link_loss_nav_state(status, armed, status_flags, internal_state, link_loss_actions_t::AUTO_RTL, 0);