commander: detect if offboard control is lost and missing offboard states

src/modules/commander/commander.cpp

@@ -661,6 +661,7 @@ int commander_thread_main(int argc, char *argv[])
 	nav_states_str[NAVIGATION_STATE_LAND]			= "LAND";
 	nav_states_str[NAVIGATION_STATE_DESCEND]		= "DESCEND";
 	nav_states_str[NAVIGATION_STATE_TERMINATION]		= "TERMINATION";
+	nav_states_str[NAVIGATION_STATE_OFFBOARD]		= "OFFBOARD";
 
 	/* pthread for slow low prio thread */
 	pthread_t commander_low_prio_thread;
@@ -932,6 +933,19 @@ int commander_thread_main(int argc, char *argv[])
 			orb_copy(ORB_ID(offboard_control_setpoint), sp_offboard_sub, &sp_offboard);
 		}
 
+		if (sp_offboard.timestamp != 0 &&
+		    sp_offboard.timestamp + OFFBOARD_TIMEOUT > hrt_absolute_time()) {
+			if (status.offboard_control_signal_lost) {
+				status.offboard_control_signal_lost = false;
+				status_changed = true;
+			}
+		} else {
+			if (!status.offboard_control_signal_lost) {
+				status.offboard_control_signal_lost = true;
+				status_changed = true;
+			}
+		}
+
 		orb_check(telemetry_sub, &updated);
 
 		if (updated) {

src/modules/commander/state_machine_helper.cpp

@@ -541,6 +541,25 @@ bool set_nav_state(struct vehicle_status_s *status, const bool data_link_loss_en
 		}
 		break;
 
+	case MAIN_STATE_OFFBOARD:
+		/* require offboard control, otherwise stay where you are */
+		if (status->offboard_control_signal_lost && !status->rc_signal_lost) {
+			status->failsafe = true;
+
+			status->nav_state = NAVIGATION_STATE_POSCTL;
+		} else if (status->offboard_control_signal_lost && status->rc_signal_lost) {
+			status->failsafe = true;
+
+			if (status->condition_local_position_valid) {
+				status->nav_state = NAVIGATION_STATE_LAND;
+			} else if (status->condition_local_altitude_valid) {
+				status->nav_state = NAVIGATION_STATE_DESCEND;
+			} else {
+				status->nav_state = NAVIGATION_STATE_TERMINATION;
+			}
+		} else {
+			status->nav_state = NAVIGATION_STATE_OFFBOARD;
+		}
 	default:
 		break;
 	}